September 2008 Mercedes-Benz StarTuned Magazine

2. TO OUR READERS IN THIS ISSUE
We lcome to StarTuned, the
4 KEYLESS GO
magazine for independent service
techn icians work ing on Mercedes- DAS and "Keyless Go" are technological fea t ures t hat
Be nz ve hicles. Your Mercedes-Benz make life easier as well as increasing the security of
dea ler spo nso rs StarTuned and Mercedes-Benz vehicles. It is a continu ing evolut ion
provides the informat ion com ing of various convenience systems. I<nowing how t hese
you r way in each issue. systems work will make diagnosing problems a
Mercedes-Benz wants to present the profitable experience .
information you need to know to
diagnose and repair Me rcedes-Benz
cars accu rate ly, quickly and the first 12 COOLING SYSTEM SERVICE
time; text, grap hics, on-l ine and other Summer is alm ost upon us, and with the warmer
tec hnica l sources co mbi ne to make weather come customers hot under the co llar about
th is possib le. air cond itionin g performance.
Feature articles, derived from
approved company sources , focus
on being usefu l an d inte resting. 20 SMOOTH SHIFTING
Our digest of techn ical information
One of the benefits of owning a Mercedes-Benz is a
can he lp you so lve unantic ipated
seamless transfer of power from the engine to the road.
prob lems qui ckl y and expertly.
Our li st of Mercedes-Be nz dealers
To add to the experience adaptive transmiss ion sh ifting
can he lp yo u find Genuine
tailors the vehic le to the driver. Let's see how
Mercedes-Benz Parts. Mercedes-Benz manages these two feats.
We want StarTuned to be both
helpful and informative, so please let
us know just what kinds of features 26 CUSHIONING THE BLOW - PART II
and other diagnostic services you'd In the last issue of StarTuned we introduced basic air
like to see in it. We 'll co nt inu e to bag maintenance and repair and as promised, here is
bri ng you se lected se rvice bulletins
part two of Cushioning the Blow. Now we'll take a loo k
from Mercedes-Benz and articles
at the Emergency Tensioning Device (ETD), further
covering the different systems on
testing and checklists.
these veh icles . J
Send you r suggestions, questions
or comments to us at:
31 GENUINE MERCEDES-BENZ
j
StarTuned
PARTS ... NEARBY I,
One Mercedes Drive I
Montva le, New Jersey 07645 Wherever you are in the United States, there's a nea rby
Phone : 1 800 225 6262, ext. 7112 source of genu in e factory parts fo r your customers'
e-ma il: StarTuned@mbusa.com Mercedes-Benz ve hicles.
StarTuned is a quar terly publication of Mercedes-Benz USA, LLC (" M BUS A"). No par t o f t h is news let ter may be reprod uced without the express written permission of
MBUSA. Editoria l and Circulation Offices: 598 Pi ne Point Drive, Akron, Oh io 44333. Caution: Vehicle servicing performed by untrained persons could resu lt i n serious
injury to those persons or others . Information conta ined in this newsletter is in tended for use by tra in ed, professional auto repair techn i c i ans ONLY. This
information is provi ded to inform these technicians o f cond i tions which may occ ur in some veh ic les or to provid e information wh i ch could assist
them in proper serv ic ing of these ve hi c les. Prop erly t rained technician s have the equ ipm ent , tools, sa fety instructions, and know-how to perform repa irs
correct ly and sa fely. If a condition is described, DO NOT assume that a topic covered in th ese pages automat ica lly applies to you r ve hi cle or that your veh icle has
that condition. StarTuned is a registered trademark of MBUSA.

3. STARTUNED
Information for the Independent Mercedes-Benz Service Professional
September 2008 U.s. $6.00 € 1
2.50 Volume 8 Numbe r 3
Group Publisher Contributing Editor MBUSA Technical Production Manager
Christopher M. Ayers, Jr. Chip Keen Content Advisor Devon Ayers
cayers@cmacomm.com ckeen@cmacomm.com Donald Rotolo dayers@cmacomm.com
Donald .Rotolo@mbusa.com
Senior Project Director Contributing Editor Circulation Manager
Tamra Ayers Kerry Jonnson MBUSA Project Manager Joann Turner
tayers@cmacomm.com kjonnson@cmacomm.com Stephen Langelotti jtu rner@cmacomm .com
Stephen. Langelotti@mbusa.com
Editorial Director Contributing Editor List Consultant
Bob Freudenberger T Nash
om Art Director NFocus
bfreud@cmacomm .com tnash@cmacomm .com JefSturm
jsturm@cmacomm.com

5. You Don't Need One
DAS and "Keyless Go" are technological features that make /ife easier
as well as increasing the security of Mercedes-Benz automobiles. It is a
continuing evolution of various Convenience systems. Knowing how these
systems work will make diagnosing problems a profitable experience.
As with any other computer-controlled We will look into how to determine if the vehicle
system , knowing how it works is half the battle has Keyless Go and how it is supposed to
of diagnosis. Some of the more high-tech function. Then we will look into diagnosing
advancements Mercedes-Benz has to offer its problems when they pop up.
owners are DAS (Drive Authorization System)
and "Keyless Go ." Both are symphonies of That Is One SmartKey
well-orchestrated computer input and output
signals creating convenience features With pre-'98 DAS (DAS2b) the actual ignition
Mercedes-Benz owners have come to expect. key can be separate or is incorporated with the
Very often, elaborate computer communication central locking system remote. The key also
schemes are required when multiple control houses a transponder. The physical key allows
units need to interface to create the desired the ignition lock cylinder to turn, unlocking the
effect. First, we will review the components steering wheel. This transponder signal is picked
involved, followed by how they work together up by an antenna around the ignition lock cylin-
to form the DAS and Keyless Go features . der. If the proper signal is sent to the immobilizer
Mercedes-Benz introduced the next evolution of control unit (or early DAS unit), the message is
DAS (DAS3) with the SmartKey feature in '98, passed on to the Powertrain CAN and the engine
and Keyless Go was introduced to the U.S. is allowed to crank and start. If an incorrect
market in 2001 on the 220 and 215 chassis, and signal is sent. the engine may crank for a short
in 2003 in the new SL-class, the 230 chassis. time, but fuel will be cut and the engine won't
By removing the physical key
and pushing down on the grey
tab, you can separate the two
parts and replace the watch-
style battery in the SmartKey.
A dead battery will only affect
the power door lock features.
Cranking and starting the
vehicle will not be affected.
StarTuned 05

6. KEYLESS GO
I
start. Chassis numbers starting with a "1 " (i.e .
163, etc.) maintained th ese separate immobi lizer
module/DAS module to control key recognition .
After '98, the newer chassis numbers starting
with the number "2" (i.e. 21 1, etc.) advanced to
the newer DAS3 SmartKey system. These
SmartKeys work with an EIS (E lectronic Ignition
Switch). This EIS takes the place of the
mechanical lock cylinder, substituting an elec-
tronic control unit. An electromagnetic coil built
into the EIS powers up the SmartKey. The key in
turn sends an infrared signal directly to the EIS
unit. The SmartKey also contains a radio fre-
quency transmitter and an infrared unit for the
central locking unit. However, if the battery dies
only door locks will be affected. Once the EIS is
awake, it sends its information to the SLM
(Steering Lock module), the ESM (Electronic
Shifter Module), and the Powertrain CAN (ME-
Motor Electronics - co ntro l unit), as well as turn-
ing on accessory and ignition power to the rest
of the vehicle . If the key is not accepted, th e EIS
is not unlocked and the key cannot even be
turned . From '01 to '03 Mercedes-Benz phased
in "Keyless Go." This feature added a card that, if
within the proper range, would al low the vehicle
to be opened and started without using the mart
key. After 2004 the Keyle ss Go card is incorpo-
rated in the SmartKey itself.
If you feel you may have a prob lem with one of
these convenience features, you need to kno w if
the vehicle has Keyless Go or not. The fastest
way to determine this is to look for the
"Start/Stop" on the top of the shifter knob . You
The Start/Stop engine button on will also notice a push button on the driver's side
top of the shifter indicates that the door handle for locking the veh icle. Another item
to look for is a push button on the rear trun k
vehicle has the Keyless Go feature. next to the trunk release handle. Finally, the
The signal is sent to the ESM and Keyless Go card is the last piece you are going to
need to verify that it is function ing properly. Now
then passed on to the Keyless Go let's see what the Keyless Go feature does.
module through the CAN. With your This feature performs a few simple tas ks such
as activating and deactivating the alarm, locking
scan tool you should be able to and unlocking the vehic le and, of cou rse, startin g
check this input in either control unit. and stopping the engine. In add iti on to these
tasks, it can also allow operation of some con-
venience features by turning on accessory power
through the EIS (Electronic Ign ition Switch) . One
thing that is required here is the Keyless Go
card. Make sure the customer drops off th e t wo
06 Stal-Tuned

7. The black trunk switch (pictured
here on the right side of the handle)
is one of the few direct inputs to
the Keyless Go module. Remember,
it is only used to lock the vehicle,
not unlock it.
cards al ong with the vehic le when investigating they wi ll not work. At this point the door hand les
any prob lem with the system . The card can be need to be pu ll ed on once to wake up the KG
stowed in the interior cabin of the vehicle or in system and the second pull shou ld unlock and
the trunk to operate the locking and unlocking open the door. Once you have entered the vehi-
feature. The card must be in the cabin in order cle with the KG card, pushing on the Start/Stop
for the engine to start. Another item you need to button on the shifter once wakes up the EIS
have in your possession is the original DAS3 accessory position. A second push turns on
SmartKey (Drive Authorization System 3). It also ignition power. You shou ld be ab le to operate all
has the ability to activate and deactivate the electron ics in the vehic le at this point. By
alarm, and lock and unlock the doors. It will also app lyin g the brake pedal and hitting the
over-ride the KG (Keyless Go) card in the event Start/Stop button the engine should start
you are stuck with a ma lfun ction. Advise the providing the ESM indicates it is in the Pa rk
customers that although they do not need to position. If none of these features work, you
use the SmartKey, they shou ld always have it need to ch eck the KG card and if the card is in
with them as backup. range of the antennas . By hitting the Start/Stop
Both t he SmartKey and the KG card have LEDs button again the engine shou ld shut off if the
to indicate when they are transmitting. These shifter is still in Park. If the driver's door is
LEDs indicate that the batteries are acceptable closed, the EIS wi ll stay on in the
in either component. If the LED s do not li ght, accessory position, and if the door is open
then the batteries need to be replaced. In the the EIS shuts off.
ca se of the KG card, the LED wi ll in dicate how
the card was last used . If the LED is red, then Knowing the Players
the vehic le was locked; if green, it was unlocked.
Either th e SmartKey or the KG card allows the Now that you know about the SmartKey,
owne r to se lect between unlocking only the immobi lizer or DAS units and EIS, we' ll move on
driver's door and unlocking all of the doors . to the more comp li cated "Keyless Go." As with
Both the door handle and trunk switches most computer contro lled systems the brains are
provide a manual way to lock the veh icle, but not in the control unit. It is almost always mounted
for unloc king. Touching or pulling on the door on the driver's side of the trunk behind the whee l
handle wou ld accomplish this. If during KG house . Like any computer it receives inputs and,
locking with the push buttons the wind ows are depending on those inputs, contro ls and
open, the convenience feature will automatica lly manipulates outputs. Some of the inputs are
close them. The door handles have capacitive directly hard-wired into the KG control unit and
sensors that discharge when touched. They are other inputs come in through the CAN (Controller
powered down after three days, so after this time Area Network). Knowing this is important when
StarTuned 07

8. KEYLESS GO
the trunk lid so the KG module thinks the trunk
Vehicle 1230.475 Control unit IKG
is closed. Th ere may also be additional deck lid
IActual values
switches t hat need to be manipulated to indicate
S2I3 (Keyless start and stop pushbutton)
Selector lever position that the trunk is c losed. This will allow the sys-
Door handle and trunk Ikt contacts
Power , up ply tem to lock th e doo rs and arm the alarm. It is
Check assignment of transmitter card to key track.
also a good was to access the battery to mon i-
tor current draw if the battery is going dead over
time.
If t he KG modu le sees the door handles
touc hed or pu ll ed, it will wake up CAN-B (Body
CAN) and have t he KG antennas signa l for the KG
card. If the card responds, then the CAN wakes
up the EIS. The KG card signa ls are received by
an antenna in the rear windshield. If th e brake
peda l is depressed and the Start/Stop button is
pushed the CAN-C communicates that the ESM
(E lectronic Sh ifter Module) is in Park and the
engine will crank and run. Since the rear wind-
The easiest way to check Keyless Go
shield is important to the KG system, care must
inputs is through the 50S.Yo u can verify be taken when rep lacing it.
that the selector lever is in park, but The Keyless Go system has only a few
contro ll ed outputs. Since the pneumatic door
keep in mind that if that was a problem lock system is too slow to un lock the doors,
the customer would have had other there are separate un lock so lenoids in each
door. These so lenoids on ly unlock the door
complaints such as a no-cronk situation. when the handle is touched or pu lled.
Coming In On the CAN
diagnosing a problem. Also, knowing what inputs
go where will tell you what control units you have As we discussed earl ier, other important inputs
to communicate with using your SDS scan too l. come in thro ugh the CAN. In order to start the
In addition, if there is a commun ication prob lem engine, the brake pedal needs to be applied. The
with the CAN, you may have to fix that first brake switc h in put does not go directly into the
before you start condemn ing components . KG modu le. To find that wi ring you have to look
Some inputs directly wired into the KG unit are at the Traction Control system where the brake
the KG Antennas that are found in the center switch is a direct input. The brake-appl ied signal
console, each door and a few in the trunk area. passes t hrough the BASI ASR/ ESP contro l unit
These antennas send out a radio signa l looking (depending on how the vehicle is equipped) and
for the KG card . When the KG card wakes up, it continues on to the KG module. In the case of an
sends a rep ly radio signal back that the card is '05 230 chassis, can evaluate the wiring diagram
the right one for this vehicle. Also, both the push provided with a pa id subscription to
button in the door hand le and trunk lock switch- www.startek info.com . The Park and Start inputs
es are hard wired into the KG modu le. You can do not come in through the CAN, but in ste ad are
use your SDS Compact III to monitor these hard- directly wired to the KG module. Thi s changes
wired inputs to quickly determine if they are sli ghtly in early '06 and later models with the
working properly. Otherwise, you have to check Park and Start inputs being supp lied on a single
the wiring directly. This can be time-consuming, wire. Either way, the ESM (E lectronic Selector
and the trunk needs to be open to access the Modu le) receives the switch inputs directly and
KG module. You will have to lock the latch on passes them along the CAN to the KG module.
08 StarTuned

9. ~ - --
,
--
Small scratches, stone impacts, dents and blemishes -
and the customer's Mercedes can quickly lose the shine
from its exterior. And because that is annoyance enough,
we keep the costs for a repair as low as possible - with
Mercedes-Benz Small Repair. Special repair methods mean
that small appearance defects vanish in next to no time.
It goes without saying that our kits meet the high, tested
Mercedes-Benz quality standards that you expect. So if your
customers are driving around with a small imperfection, it
may be able to be repaired with Mercedes-Benz Small
Repair. Small Repair Kits are available from your authorized
Mercedes-Benz dealer.
Training on the Small Repair methods are available from
Reliable Automotive Equipment. Please contact Reliable
Automotive Equipment to inquire about training your
staff to perform these repairs quickly and efficiently.
RAE RELIABLE AUTOMOTIVE EQUIPMENT, INC.
1.800.328.7855

10. FEATURE ARTICLE
Why We Do What We Do
Put any two different materia ls together and
chances are they are going to react with one
another. Some reactions will happen quicker
t han others, but eventua lly someth ing is going
to happen . The same dynamic happens within
the cooling system of any engine. In modern
engines, alum inu m alloys make up the blocks
and cylinder heads. The se aluminum alloys are
more reactive than their iron or steel alloy
counterparts. Coolants that run through these
aluminum components often react with them,
breaking down both the coolant and th e alu-
minum. The debris from th is reaction gets
circulated throughout the cooling system. It
often bui ld s up in small cavities found in places
like the rad iator and/ or heater core. Eventua ll y,
t he passages become blocked and circulation is
reduced . These contam inants can also build up
on thermostats, po ss ibl y causing them to stick
Ask anyone what a "cool ing system service" is and you closed. We all know a closed thermostat will
will probably get the tried-and-true answer of draining and restrict coo lant flow to the engine and resu lt
refilling the coo ling system. Thi s is common ly reduced to in overheatin g.
draining the radiator and refil ling it. But what is the pur- To prevent this corrosion effect on cooling
pose of servicing the coo ling system? Was the veh icle system component s, we rep lace the coolant. It
overheating? Will the engine overheat in the fu ture? Th ese removes t he corrosion contaminants and
days, coolant has become much more than the "green restores higher boiling points and lower freezing
stuff." Phosphates, organic ac id compounds and other points within the cool ing system. Mercedes-
additives add to the confusion: Can I mix this with that? Benz maintenance schedules have you replace
Do I have to flush the whole system? What co lor shou ld the coo lant at 147,000 miles or 15 years. These
the coolant be? This may sound si lly, but when you per- maintenance schedu les are dependent on use
form some service work (rep lacin g a thermostat) you will of approved a nti-corrosion / anti-freeze coolants
lose some coo lant. You need to know what coo lant is and you are required to check the cool ing sys-
compatible with what you already have in there . Wi ll you tem at each service. Mercedes-Benz factory
pick one of the aftermarket so-ca ll ed all-purpose so lu- coolant (Part # Q 1 03 0002) meets all the
tions? Will t he coo lant you use breach the customer's requirements to achieve these low-maintenance
existing warranty? Understanding the requirements of interva ls. Money saved putting in a less expen-
Mercedes-Benz ve hicles wi ll make the decision-making sive coolant is often lost in the long run with
process easier. clogged and corroded components requiring
12 StarTuned

11. The Mercedes-Benz coolant
is a cost-competitive option
that many of us do not think
about. It contains the
® Mercedes Br.tlZ necessary corrosion additives
Anticorrosion! and is ethylene glycol-based,
Antifreeze AGENT
Pnlecls 'iUli.tJJ.... elBlne frGlIlca ....siOll
so we can use a regular
c."".,....
.IId IteezinJI .l1li rlllSes ll1e bclllog pOflll.
10 1118 $p.. lII.ati... , ...
1Ie1lllt. P"'dIIdB .... at Ito. 325.' hydrometer and refractor
Q 1 030002 to test it. It is also clear,
UrMU,S.,6dm ·3.lBlLIJI1f5
......
'lRII~~.tJlfJUl.F ~lItft-.aEJ .
~.~~
which make contamination
easier to spot.
replacement, as we ll and add itiona l coo lant cool in g system pressure test is ca ll ed for.
flushes. We should all agree that the minim al Commercial testers are ava ila ble from yo ur tool
money saved on coo lant does not come close to supplier along with the necessary coo ling system
the cost of a cooling system repa ir. Th e labor adaptors. Simply pump up the system to the
time on a coo ling system services varies from 1.0 rated pressure capacity of the rad iator cap and
to 1.5 hours depending on th e model. Let's go see if the pressure drops . If it does, look for
over how we are going to test to see if the externa l leaks. You may also want to attach an
coo lant is up to the task . add iti ona l adaptor and check the cap. If you can-
not find any externa l leaks, it' s t ime to look at
A Few Minutes Testing the possibili ty of an internal leak . In th e last
iss ue of Star Tuned, testing for head gasket
Th e first th in g we are taught about testin g problem s was covered, so look there for
cooling systems is a visual check. Look in g at the those answers.
coo lant level and the coo lant itself is the first If the coo ling system passes the pressure test,
test we should perform. Cool ing systems that are it's time to test th e coo lant itself. Mercedes-Benz
not up to leve l at some point had a problem. recommends testing th e coo lant at every service
Either the coolant is leaking out somewhere, or (i .e. oi l change). Thi s can be done one of two
it's being used by t he engine. At thi s point a ways. Th e first method invo lves a coo ling system
StarTuned 13

12. COOLI NG SYSTEM SERVICE
hydrometer. This too l measu res the specific
gravity of the coolant, specifically ethylene
glyco l. This specific gravity is a measurement of
coo lant concentration. The ideal mixture shou ld
be 50% coo lant and 50% water. This ethylen e
glyco l mixture's spec ific gravity wi ll be affected
by the tempe rature of the fluid, therefore a
coo lant hyd rometer's scale needs to be ca libra t-
ed to a specific tem perature. You can use your
infrared temperature gun to determine the
liqu id's te mperatu re and have it match the
temperature of the hydrometer scale. Remember,
specific gravity changes with temperature. A
50/50 mix of ethylene glycol will have a specific
gravity rea ding of 1.057 at about 100 deg. F. If
the ve hicle came in and the coo lant was 150
deg. F., the same good mixture wou ld yie ld a
reading of 1.037. If yo ur tool is ca librated to 100
deg. F. yo u would think the concentration was
35%, so make sure you know what temperature
yo ur hydrometer is cal ibra ted to.
Th is too l dra ws coolant into a clear plastic tube
with either we ighted balls of varying density, or a
single float pivoting on a pin. See how many balls
fl oat or how fa r the single float rises and that will
indicate the specific gravity of the coo lant. Air
bubbles in the samp le affect the buoyancy of the
fl oat as we ll . Even expensive hydrometers have Here are the tools of the trade.
the same problems. Be lieve it or not, this tool is
ofte n not precise enough to give you a read in g Mercedes-Benz factory coolant is
yo u ca n depend on . Also, the hydrometer cannot ethylene glycol-based, so a coolant
be used on propylene glycol-based coo lants
since two different concentrations can yie ld the hydrometer will work fine. Hydrometers
same specific gravity rea dings . Mercedes-Benz are not the most precise method of
brand coo lant is based on ethylene glyco l, so you
can use a hydrometer to test it. Remember,
measuring concentration. The refractome-
te mpe rature variations still have to be taken into ter is much more accurate. Remember,
co nsidera tion . Could the re be a better way?
It is more expensive than a simp le hydrometer,
coolant temperature affects the specific
but the refractometer is very capab le of preci se gravity of the sample. Know what you
measureme nts of coo lant concentration . Th e
gouge is calibrated for.
principle is simp le. As light passes through a
liq uid , it will bend a different amount for a differ-
ent liqu id, in our case a different coo lant concen-
tration. By usi ng a refractometer, you send li ght
th ro ugh tje coo lant sample and see how the light
bends on the refractometer sca le. You then
co mpa re t hat sample to water. Either ethylene
glyco l- or propylene glyco l-based coo lants can be
14 StarTuned

13. measured with a refractometer. The temperature
of the coolant mixture still affects the read in g,
but since the samp le is so sma ll (on ly a drop)
the liquid quickly assumes the temperature of
the too l.
Simply put a drop on th e len s, close the clear
cover and point the refra cto meter into a light
source. A meter of good quality will have yo u
ca librate it by first samplin g distilled water.
Once ca li brated, you can samp le your coo lant
and check the conce ntra tion .
How We Do What We Do
For maintenance or service work, yo u may
need to rep lace the coo lant. How ca n you do
this qu ick ly and be profitable?
The first step in a coo ling system service is to
dra in the existing coo lant from t he radiator.
There is usually a drain va lve on th e driver's side
or passenger's side tank of th e radiator. After
removing the cap of the coo lant system expan-
sion tank (to allow air into th e system), you can
raise th e vehicl e. Then, open th e drain plug on
the radiator tank. This will only drain the radiator
and some portion of the water pump and
thermosta t hous in g. The next step is to drain
the block. Thi s is often ove rl ooked due to the A vacuum-assist tool can save a lot of
lack of kn owledge of where the drain plugs are
and acces s to th em. With a paid subscription to time in bleeding the system. Generally,
www.startekinfo .com. you can view service Mercedes-Benz engines do not have a
procedure s to locate the drai ns. These plugs are
located at the base of the water j acket on one or problem with bleeding out air, but this
both sid es. Th ey will often be difficult to remove, helps eliminate the possibility. Shop air
so be careful not to round off the bolt head.
This is probably the most time-consuming part
often powers up the vacuum pump.
of the process. Once the cooling system is in a vacuum,
Refilling the system used to be simpl e.
Add coo lant to the expa nsion tank and let the
a valve is switched and fresh coolant is
engine run . If there we re some problems in filling drawn in to fill the vacuum.
a system, an old trick was to prop th e thermostat
open with two pieces of aspirin wh il e filling the
system. Thi s wo ul d give th e air a chance to
escape as the system filled up with coo lant.
Although we are not aware of aspirin caus in g any
problems currently, with new coolant addit ives,
radiator sea ls and gasket materials all sorts of
reactions may take place. Mercedes-Benz coo l-
ing systems have the expansion tank at t he
highest point, so are self-b leed ing.
StarTuned 15

14. COOLING SYSTEM SERVICE
These days with dual heater cores, auxi liary
cooling pump motors and externa l cool ing
If You Want To Pull Out
system plumbing, there is a mu lt itude of places The Big Guns
air can get trapped . This can lead to symptoms Another too l investment that will save you
such as overheating and poor heater perform- t ime, ensure all of the coo lant is being
ance . You may have to run the engine for a exchanged and reduce air in the system, there
whi le before you bleed al l the air out. Check are coo lant exchange machines . These no longer
the service procedures and see if there is a require that you put the vehic le on a lift and
bleed procedure for the particular veh icle yo u open dra in plugs on the radiator and engine
are working on. block. As long as you have access to a coolant
There are tools avai lable to assist you in the hose, you can exchange the old coolant with a
refill procedure. You have probably heard of "vac- fresh supply with a minimum of mess.
uum assist" cool ing system fillers. These too ls These mach ines have externa l tanks you can
use your shop's compressed air supply and a pre-fi ll with yo ur 50/50 disti ll ed water and
vacuum pump to generate a vacuum in the coo l- antifreeze coo lant mix. The next step is to
ing system . Once the system is in a vacuum, a disconnect the upper radiator hose and connect
val ve allows coolant from a pickup tube to fil l t he the coo lant line adaptors from the machine to
vacuum in the coolant passages. This can reduce the car. Most coo lant exchange machines do not
and/or eliminate any air bound in the coo li ng need the vehicle to be warmed up, or even
system . There is no need to run the veh ic le for running. A vacuum pump pumps out the old fluid
an extended period of t ime to self-bleed the air into an empty tank and replaces it with the
out of the system . You can now move on to yo ur coo lant prepared in the refill tank. You shou ld
next job. know by now the type of anti-corrosion/ anti-
If you wou ld like to comp lete the task of drain- freeze we sho ul d be using in Mercedes-Benz
ing the coo ling system, you can flush out the vehicles, but th is is on ly half the equation .
heater core. Removing contaminants wil l improve
heater function and prevent further blockages Water Quality
down the road. The great part here is the time In th is article, we discussed proper cooling
saved. Most Mercedes-Benz vehicles use an aux- system service procedures, anti-corrosion anti-
iliary coo lin g pump motor. Th is motor can be freeze and too ls to test and exchange the
activated through the use of your Compact III coo lant. One more subject we need to discuss is
scan too l, or by just supplying power and ground something we very often take for granted. Th at is
to the pump motor directly. The motors draw water supp ly. "C ity" water for drinking is treated.
only about .5 amps and wi ll pump all of the It contains fluoride or ch loride salts due to the
coolant out of the heater core wh ile you are treatment, so it is not desirable to mix it with
refilling it with new coolant. Most pumps are on coo lant. Do not use this, or hard water, in
the output side of the cooling system. Mercedes-Benz coo ling systems. In the odd
Disconnect the line on the pump returning the chance you have a supply of spring water, either
coolant t o the water pump and run it into a con- bottled or from a wel l, do not use this, either.
ta iner. Block the water pump side of the line you Bottled water is not regulated and probab ly
have just disconnected and run the pump until contains minera ls that can react with engine
you see new coo lant. We wou ld not recommend components, and also acts as an abrasive when
using any aftermarket coolant flushing solutions passing through the coo lin g system . Instead,
as these may conta in ha rsh chem icals that can use disti lled water. It is the best to use since it
attack seals and gaskets after a few thousand conta ins no additives. Th e slight additional cost
miles. If the cooling system is maintained in a of disti ll ed water shou ld not significantly increase
timely manner these "coo ling system repairs in the cost of the overal l coo ling system service
a can" should not be necessary. and eli mi nates harmfu l contaminants.
1 S
6 tarTuned

15. +
Distilled
Water
Here is a tool that might be a In Conclusion
good investment providing you sell Cooling system service is one of the simpler
enough cooling system services. tasks you perform for your customers, but it is
also one of the most important. Advancements
You can keep one tonk with a in the chemical composition of coolants and
50/50 mixture of Mercedes-Benz cooling system plumbing make corrosion and
air-bound systems real problems that need to be
coolant and distilled water and addressed . Using Mercedes-Benz antifreeze will
exchange it with the old coolant in sure corrosion protection and warranty claims
will not be an issue . Draining the block, radi ator
without even running the engine. and heater core will insure all expired coolant is
You may still have to pump out removed . Finally, refilling the system without air
pockets can be accomplished with a vacuum-
the heater cores separately. assist tool, or a coolant exchanger. If customers
notice your attention to detail on the cooling
system, we are sure they will trust your
judgment when it comes to more involved
repairs, and that is good for all.
StarTuned 17

16. Replace - We replace more parts than aftermarket brands.
Engineered - Designed to meet original OEM drawings.
Manufactured - Made with same OE components as factory parts.
Assembled - Completely assembled from components and not just repaired.
N - Tested to new unit standards.
ew
Improved Technician Efficiency

17. 260E 1987-1989
300CE 1988-1993
300EITE 1986-1993
300SE/ SEL 1988-1991
300SL 1990-1993
MODELS
A 0002300511 80 350S0 1991 C240/C320/S430
3SOS0L 1990-1991 AOOO 230 9111 80 S500/CL500/CLK320
2004
E320 1994-1995
SL320 1994-1997 E320/E500 2003·2006
SL600 1996·1997 A001 2301211 80
CLSSOO 2006'"
400E/SOOE 1992·1993
500SL 1990·1993 ML350lML500lML55AMG 2003'"
A 0002300611 80 E420 1994-1995 A001 23028 11 80
E500 1994 G500/G55 (NOT G55K) 2003+
SLSOO 1994-1999
A001 230 68 11 80 ML320/ML430 UPT02000
1900 1986·1989
1900T/3000TI TOT 1987 S55AMG/CL55AMG 2003·2005
190E 1985·1993 AOOO 230 90 11 80 C240/C320 UP TO 2003
260E 1987·1989
300CE 1988·1989 CLK320 2003
A 000 2301111 80 3000 1987·1993
300E 1986-1992 AOOO 230 781180 C32AMG KOMPRESSOR 2002·2004
300SE 1988·1992
300SEU TE 1988·1991 AOOO 230 97 11 80 2004
E3000 1995
C2201C280 1994-1995 S600/CL600 2001+
A 000230 1311 80 C36 AMG 1995 A001 230 0111 80
S6SAMG/CL65AMG 2005+
300S0 1992·1993 E55AMG 2004-2006
300SE/600SEC 1993
600SEL 1992·1993 CLSSSAMG 2006
A 000 230 17 11 80 S3201 S3500 1994-1995
S420 1997·1999 A001 230 1411 80 E350/ESSO 2007
S600 1994-1996
CLS550 2007
CL600 1998-1999
S320 1995-1999 E320CDI 2005-2006
A 000230 2211 80 S3500 1995
CLK550 2007
S600 1996·1999
CLK55AMG 2003'"
1900 1986-1989 A001 2301911 80
1900T/30001 OTI TOT 1987 SLKS5AMG 200S...
190E 1985·1993
260E 1987·1989 CSSAMG 200S'"
A 000 230 2411 80 300CE 1988·1989
300E 1986·1992 2004
300SE 1988-1992
300S0L 1986·1987
300SEUTE 1988·1991
420SEU 560SECI SEL 1986·1991
A 000 2302511 80 560SL 1986-1989
400SE 1992
400SEU 500SEC 1993
A 119 23000 11 80 500SEL 1992-1993
S420/500 1994-1995
C280/C43 AMG 1998-2000
CLK320 1998-2003
CLK430 199~2003
CLK55 AMG/ML320 2001-2002
A 000 2307011 80 E320 1998-2002
E430/E55 AMG 200G-2002
ML430 199~2001
ML55AMG 2000
SLK230/SLK320 2001 - 2004
CL500 2001-2003
CL55 AMG 2001-2002
A 001 23002 11 80 2002-2003

18. FEATURE ARTICLE
a
seaml s transfer of engine to the road.
To add to the experience adaptive transmission shifting
tailors the vehicle to the driver. Let's see how
Mercedes-Benz manages these two feats.
How do we isolate a drivabi lity issue from a The job wi ll remain profitab le if the first step is in
transmiss ion shifting issue? Th is may sound the right direction. In the case of a drivabil ity
simple, but a bucking sensation may fee l li ke a prob lem/transm ission shift issue, you need to
misfire when it is actually a transm ission va lve determ ine if it is one or the other because there
body control valve com ing in and out. Even if we are two different should give the technic ian an
determine that it is a transmission problem, how idea on what might be wrong and where to look .
do we isolate if the problem is with the mechan i- Try different driving patterns, such as different
cal part of the transmission or the computerized rates of acceleration. Also, try manually shifting
electronic controls? Proper testing methods have the automatic transmiss ion . You can try holding
never been as critical as they are today. The the transm ission in a fixed gear and see if you
expense of an improper diagnosis lead ing to an can duplicate the problem. Remember, the
impro per repa ir can leave the customer with a transm ission contro l unit wi ll limit the rpm
bad taste in his or her mouth. You need to be of the engine.
sure of your test methods and know how to eva l- Another form of testing is to observe how the
uate the ir results. Self-diagnostic features incor- system functions and see if we f ind anything
porated in contro l units today have helped in the wrong, either electronica ll y or mechanically.
battle with complexity. Th is coupled with proper We can also make a change to the system,
training and information should leave you capa- either electrica l or mechanical, and see how
ble of isolating the problem and performing the the veh icle reacts.
pertinent repair. Observing inputs and outputs can be time-
consuming on comp lex systems. This fac t is what
In The Beginning made scan tools so prevalent. With a scan tool
you can obse rve computer controls easily.
The first step in any diagnostic process is However, th is is processed data and it's relatively
arguably the most critica l. Going off in the wrong slow depend ing on the nature of the problem.
direction can waste an incredible amount of time Processed computer data is not real-time, like
that you will more than likely not get paid for. what you see on an oscilloscope. It is entirely
20 StarTuned

19. ATF
Th e next major step is to check the fluid level.
On later model Mercedes-Benz vehic les, thi s is
not a simple as it sounds. You wi ll find the fill
tube, but you will probably not find a dipstick.
The dipstick is now a tool to be kept by your tool-
box. In add ition to having the tool at your dispos-
al, you also need to have the transmission at a
spec ific temperature. Too hot or too cold may
not give an accurate reading. The fluid level
You will need to have this tool at shou ld be checked at 25 deg. C (77 deg. F.), and
it should read between the "Max" and "Min"
your disposal if you are going to marks on the dipstick tool. Allow the engine to
service Mercedes-Benz vehicles. warm up about 2 minutes and bring the trans-
mission temperature up to about 80 deg C (176
The vehicle has no dipstick so you deg F) and the level should still be between
need to provide your own. Measure "Max" and "Min" on the stick. The transmission
needs to be in a drive gear, so make sure the
the ~uid level in a drive gear with parking brake is on and have a second techni-
the temperature of the ~uid first at cian in the veh icle applying the brakes. If repair
work has been carried out have the technician
25 deg C and then at 80 deg C. move the selector lever into each gear a few
times to evenly distribute fluid throughout the
possible for an input or output to misbehave and
transmission.
the comp uter's self-diagnostic system never
Of course, there are always debates on what
picks it up . A scan tool is a good way to get
type of transmission fluid to use. In the case of
started when monitoring the computer's contro l
Mercedes-Benz, use only the exact ATF recom-
of the system, but it shou ld always be followed
mended in the service literature or owner's
by testing the system visua ll y and with direct
manual, wh ich you can be sure is of the proper
electrical testing.
viscosity and conta ins the necessary friction
StarTuned 21

20. TRANSMISSION MAINTENANCE
misfire . While driving, you may want to look at
the misfire co unter t hrough your SDS. If you do
not see any misfires, then you are probably
dea ling with another problem . Th is is an example
of observa nt testing. Another type of testing is
"intrusive" testing. Here, you make a change to
the system and see how the vehicle reacts. To
see if a transmission solenoid is toggling, you
simply need to unplug the main connector and
t he trans mi ssion . Th is connector, very often,
ca rries t he power, ground, or both to the trans-
mission shift and pressure control solenoids.
By unplugging it, we are forcing the transm ission
into its "fa il-safe" program. For example, if the
unit is stuck in a parti cu lar gear, eliminating
electronica lly-contro ll ed sh ifting isolates the
mechanical transmission from its electronic
control.
If the problem persists, you have two choices.
Transmission ~uid ~ushing can Either look in other areas such as the engine, or
extend the useful service life of the the problem is in the mechanical function of the
tra nsm ission. With the transmission in "fail-safe"
transmission. It can remove ~uid yo u must be carefu l of engine rpm, and exces-
that has been over-heated and is sive road-testing can actua lly damage the
transmission. Thi s type of testing should on ly
full of clutch material. It cannot be applied if the se lf-diagnostic system and
make up for worn clutch discs, so scan data are not giving an ind ication of
what is wrong.
make sure the customer is aware If the problem is el iminated by unplugging the
of the limitations. solenoid connecto r, plug it back in , watch the
control of these solenoids and monitor the input
modifiers. You may have read on the in ternet data to see if either is caus in g the symptom.
that any synthetic transmission fluid may be With older transmissions, monitoring the line
used with no adverse affects, but those that have pressures and so len oid operation was not very
not been tested by Mercedes-Benz will vo id any difficult. With newer, smoother-sh ifting transmis-
warranty on the unit, and may not provide the sions, however, this can be more cha llenging.
necessary fil l-for-life protection the facto ry f lu id Thi s type of testing may not work in every case,
offers . Th is is imperative on t he later model but it should apply in most. Mercedes-Benz vehi-
72 2.9 seven-speed transmission. The Mercedes- cles are very good at self-d iagnosis, and very
Benz part# A001 989 45 03 is developed spec ifi- often a code is stored ind icating wh ere the prob-
cally for this transm ission. It's higher friction lem may lie. Howeve r, if we do not have a code
consistency and therma l stability is required and to work with , we still have a starting po int.
it shou ld not be mixed with another type of fluid
during a service.
The Mercedes Way
Back To Our Problem How wou ld a transmission control unit tell if
the qua lity of the sh ift is less than perfect? It
Evalu ating an unusua l symptom like a light cou ld monitor t he current draw of the shift sole-
bucking with steady throttle, you may think no id, but that would on ly inform you of shifting
22 StarTuned

21. - !QI '
Vehicle [211.065 Control unit [Erc Vehicle
Read out fau n memory of transmission control unit and process stored fault Ic urrent ETC Ac t va I va I ves 1/3
codes. ~ .6 ~------------
IFiltersta! Planet . speed sensor n2 ~~~._~_
.. . . rpm ,.
VG-Tron. 02 Planet. speed sensor n3 ~~~._._
... _ rpm III
ME2-SFI . 31 Turbine speed
Quick teot IIIE r pm
03 iilual/deSiredliiar
0S Low range program
ON/s.
~tr
Most of the time Mercedes-Benz Looking at scan data, you can
computers are capable of determin- sometimes find large problems with
ing a problem with their self-diagnos- sensors, providing they lost long
tic system. Here, a few codes have enough for the computer to pick up.
set on this 2 I I chassis, and two of In this case, the rpm sensor #3 is
them are related to the some foiled no longer supplying a signal. You
sensor: #3 rpm speed sensor. This should bock up this conclusion with
sensor should now be tested directly electrical testing of the sensor. Look
to make sure the problem is not a at both the resistance and the AC
wtrlng Issue. voltage signal.
problems where the electronic controls created tells you the transmission shaft speed sensor's
the problem. If the problem is mechanical, the function is critical to the operation of the trans-
control unit would need another way to tell if mission electronic control. You need to verify that
there is a problem . Incorporated into the trans- these signals are working properly before you can
mission are input and output shaft speed sen- start condemning other components.
sors. On the later model 722 transmission, three Mercedes-Benz engineers provided additional
speed sen sors are used. The first picks up the monitors for components related to shifting. You
turbine shaft speed, the second picks up the can evaluate a shift by monitoring action of the
speed of the planetary gearset, and the output fluid. By watching how long it takes to fully apply
shaft speed sensor does just that - reads output the clutch pack and how much pressure is
shaft speed. required to engage it, you can find out if the
By monitoring these speed sensors, along with clutch packs are healthy. If excessive time and
the actual sh ift point, the transmission control unit pressure are needed to provide grip for the
can see if the proper relationship is maintained clutches, they are probably worn. The SDS tool
between th e two.. If the input shaft indicates a allows you to access this data for each clutch
higher speed than the output shaft speed sensor pack. This is extremely helpful when you find
(for a given gear ratio) then the engine rpm must shifting problems only in particular gears.
have flared as the transmission slipped into the In the later model Mercedes-Benz transmis-
next gear. This can be accomplished even if the sions, there can be up to seven forward gear
problem is not severe enough for the driver to ratios . You will have individual forward gears and
notice. To monitor these signals directly is difficult torque converter lockup for each gear. The oper-
even with an experienced lab scope user. This also ating pressure is controlled by a pressure control
StarTuned 23

22. TRANSM ISSIO N MAIN TEN ANCE
•••
Vehic le
Vehicle 1211.022 Control Lnit II:TC
(Current ETC Ac t va I va I ves 113
= .6
jFilterstiJI Planet . speed sensor n2
f--- - - - - - - !Adaptation data
VG -Tr . ~ 02
_
Planet .
l1li r pm '.~~iII!I
speed sensor n 3
1I/I
'. BIiI _ rpm ~~~._~_.
ME2-Sf l . 31 Tu r bine speed
Quick test II!IiII rpm
0 3 iIIvaltdesiredliiar
05 Low r ang e pr ogr am
ONtS.
~Vt'
Notice how you are given the
maximum and minimum limits
Using the 50S, you can select for each reading, followed by the
'Transmission Adaptations" and view actual reading. You are olso given
the readings. These will indicate the {til the reading at three temperatures.
time for each clutch or brake, as well A higher (positive) number indi-
as the {til pressure. By viewing the cates that more time and pressure
numbers you can determine if the is required to engage the clutch,
transmission needs to come apart. which implies that the transmission
IS worn.
solenoid. In addition to the primary pressure
contro l so lenoid, each shift soleno id has its own Service Work
pressure control solenoid. This allows for quicker
and smoother sh ifts. If any of these solenoids If one of the solenoids or speed sensors needs
were to stick, it would contribute to an improper to be replaced, it will probably be serviced as a
shift. Let us look at an example of this data that unit. On many later mode l Mercedes-Benz t rans-
we can use to test the solenoids . The first line of missions, all of the solenoids and sensors are
data is the "Fi ll Time of Clutch XX," with the incorporated into a plastic housing usua lly mount-
letter designation of t he clutch you are looking ed on top of the va lve body. Whi le this may
at. For ease of interpretation, you are given the increase the overal l cost of a component replace-
high and low limits of the shift monitor counter. ment, it does provide for ease of service . Typically,
The next line you is either the "Brake or Clutch transmission service work is farmed out to a rel i-
Fill ing Pressure" in mil libars. This informs us of able transmission rebuilder. A properly trained
the pressure required to apply the clutch . If either technician can, however, dra in and remove the
excessive time or excessive pressure is required pan, remove the valve body (being ca reful to
for engagement, the clutch is worn or pressure is watch the seals) and replace the solenoid/sensor
inadequate to comp lete the engagement. To plate. In the case of the 722 transm ission, the
further assess th e problem, you can also reset transmission control unit is incorporated into the
the adaptations. This "zeros" out the adaptations solenoid/sensor plate. Superior Mercedes-Benz
and gives you a new starting point. A road test engineering should make this a rare fa ilure with
that runs the ve hicle through all of its gears wi ll proper maintenance. There are also some other
allow the adaptations to take place so you can key service procedures for the 722 transmission .
re-evaluate the shift data. This is very useful The housing is magnesium so aluminum bolts are
information when trying to determine if a replace- used . Th ey must be replaced when removed, then
ment transmission is in th is vehic le's near future. torque according to specs.
24 StarTuned

23. A Mercedes-Benz should be true to its origins. So
Mer cedes-Benz Classic Center When you want authentic parts, only the source will do. M"UC"'.IIOO'~J
To speak with our Parts Experts, call our Parts Order Desk at 1-866-MB-CLASSIC (1-866-622-5277) .
Mercedes-Benz Classic Center USA, 9 Whatney, Irvine, CA 92618
Call or visit for additional details and a copy of the limited Parts Warranty. © 200a Mercedes-Benz USA, LLC

24. Cushioning the Blow
In the last issue of StarTuned we introduced basic air bag
maintenance and repair and as promised, here is part two of
Cushioning the Blow. Now we'll take a look at the Emergency
Tensioning Device (ETD), further testing and checklists.
26 StarTuned

25. Mercedes-Benz has always been at the ETD. The first stage uses an electric motor to
forefront of occupancy safety. In 1969, United pretension the seat belt in order to secure the
States Federal law mandated automatic individual in the seat. This is often in response to
occupant restraint systems. Yet, since 1967 a signal from the BAS control unit (Or ASR/ESP
Mercedes-Benz had been developing airbag unit) in the event of a panic stop. The second
technology for its passenger vehicles. By 1980, stage uses a pyrotechnic ignition squib to fire a
the company had started to employ this charge to tighten the belt even further if there's
advanced technology on a growing number of its an impact. There are also force limiters to slowly
vehicles. Initially, there were some of the same slacken the belts during certain accidents.
concern s that we hear about today, such as how As mentioned earlier all you have to do to
to prevent secondary injury as a result of airbag test the system once components have been
deploym ent, particularly as relating to children replaced is simply turn on the ignition key. Every
and smaller passengers. time you cycle the key, the SRS does a compre-
Supplemental Restraint Systems (SRS) hensive self-test during the four to 20 seconds
have come a long way since the early that the airbag warning light is on . There is no
generations. Complex computer algorithms need to evaluate the system once this self-check
differenti ate between smaller and larger impacts, has passed. There may be codes in the system,
seat occupancy detection sensors prevent airbag but these are past problems or at least problems
deployment if a light-weight individual (child) is that are not occurring at this time. We recom-
sitting in that seat, and dual/multiple-stage mend clearing all codes in the SRS after repairs
airbags have been only a few of the advance- have been completed. This will help the next
ments made over the years. technician working on the system to properly
diagnose the current problem without any
wasted effort.
Emergency Tensioning Device Of course, some other critical components in
the SRS are the acceleration sensors, otherwise
Another component that needs to be replaced known as crash sensors. These are placed in
in the event of an accident is the Emergency strategic locations throughout the vehicle to help
Tensioning Device (ETD). The ETD is a pyrotech- determine the point of impact and the severity of
nic component that retracts the seatbelts during the crash. The SRS control unit also has an
impact to keep the occupant in the proper posi- acceleration sensor built into it and it is often
tion for contact with the airbag and distribute mounted on the transmission tunnel between the
some of the pressure exerted on the occupant's driver's and passenger's seats. This sensor read-
body more evenly. The ETD is commanded to ing, in combination with the satellite sensors
deploy by the SRS control unit when an impact is placed around the body, help the SRS control
sensed. If the impact is not severe, the SRS con- unit learn the facts about the direction and level
trol unit can activate the ETD without the airbags of impact of the collision. The control unit also
in only th e seats that are occupied. Both front houses a roll-over sensor that determines that
seats have this feature and some rear passenger conditions exist for an impending roll-over. All of
seats closest to the doors. The SRS control unit these sensors help the computer logic decide
uses the Seat Belt Buckle switch to determine what airbags need to be deployed and when.
what seats are occupied . These switches can be For instance, in the event of a side impact the
the source of a self-diagnostic code and can be side or curtain airbags would be deployed. The
monitored on you factory scan tool. SRS control unit also receives signals from other
Most Mercedes-Benz vehicles utilize a dual-stage control units on the network, such as the BAS, to
StarTuned 27

26. COLLISION REPAIR / AIR BAGS PART II
With a paid subscription to www.startekinfo.com. you can access information such as
component location of the driver's seat ETD found mounted here in the B pillar. These units
have a pyrotechnic charge that fires and applies tension to the belt even if the airbags do
not deploy.
indicate a panic stop, and if the ETR needs to be key in the off position. Also, identify if the vehic le
deployed in either the first or second stage has the Dual Battery system, and, if so, discon-
before impact. nect the other one as we ll. Then, unplug the
component you would like to test and insta ll a
jumper plug of a fixed resistance between the
A Short Checklist
two pins of the component, such as the driver's
When it comes to diagnosing a problem in the side airbag squib, the passenger side ETR squib,
SRS, you wil l find no better tool than the SRS or the front acceleration sensor. Measure the
control unit itself. As mentioned earlier, if it resistance of the circuit with your DMM . Of
detects a problem in the system it will flag a course, this testing cannot be performed with
code for the components in question. Testing is the airbags connected to the system as there
relegated to measuring circuit integrity between may be an accidental deployment of an airbag.
the SRS control unit and each of its inputs and Resistance should read the same as when you
outputs. Be sure to only unplug the SRS control installed the jumper, although a few tenths of an
unit with the battery disconnected, or the ignition ohm higher is acceptable to account for the
28 StarTuned

27. Enticingly graceful and dynamic.
Strong support, too.
QUALITY FIT PERFORMANCE VALUE SERVICE
WARRANTY
Ellery part comes with the reassurance
oj a strong 12-month/unlimited-mileage
limited warranty- with additional aJllemge
}'or engines and transmissions:
Unlike any other.
The part is just part of the story. The precise fit and superior performance of a Genuine Mercedes-Benz
Part is a given. But equally important is that each Genuine Mercedes-Benz Part - down to the last nut,
bolt and gasket - comes with the unmatched technical support and expertise from your dealer and
Mercedes-Benz. All evidence of our constant dedication to supporting your business in more and better
ways than anyone else. And that's the best part. Visit mbwholesaleparts.com or contact your dealer. Mercedes-Benz
'See your Merr:etles·8enz dealer for details and a copy Of the Merr:etles·8enz ((eplacement Parts Limited Warmnt)(

28. COLLI SIO N REPAIR / AIR BAGS P RT II
A
additiona l labor involved in removing and
reinstalling components to access the problem.
This wasted time is probably coming out of
your bottom lin e on the job.
The Importance of
a Proper Repair
In the course of a body repair job, there may
be the temptation to cut costs by using aftermar-
ket, or even used parts. These parts have already
been involved in some incident that sent the
veh icle to a sa lvage yard in the first place and
have been sitting there exposed to the elements.
This often leads to corrosion . These conditions
can wreak havoc on internal circuitry and result
in unpredictable operation . It could be a liability
This is a driver's door airbag on an ML series. nightmare if corners were cut that provide less-
than-adequate SRS operation if another accident
Notice how the unit is riveted in to provide
occurs. This may also put you in hot water with
clearance for the window, so nuts and bolts
the in surance company that is footing the bill for
should not be used as a substitute. the repair. The company will often guarantee the
work it has insured, and may force you to absorb
wiring in the syste m. If the resistance is
the cost of substandard components and work-
abnormal ly high, it indicates an open circuit or
manship. So, it makes sense to use only genuine
poor connection somewhere in the wiring. If the
Mercedes-Benz replacement parts available from
test value is lower than the resistance of the
the parts department of your authorized
jumper, there is a short between the two wires
Mercedes-Benz dea ler.
you are testing. If the resistance it acceptable,
yet you still flag a code, you are probably dealing
with component failure.
Depending on the location of the harness
being tested, you may have to replace the who le
harness or find the damaged wiring in the exist-
ing harness and repair it. In the case of the
acceleration sensor, one wire comes from the
SRS control unit and the other wire continues to
a grounding point. You will need to test resist-
ance between the single wire on the SRS contro l
unit and ground to determine if the wiring is the
problem, or that there is a failed component.
With all the SRS components installed in the
vehicle and everything else safe to connect the
battery, you can turn on the key and verify that
the SRS/ Airbag li ght goes out. If not, you can
retrieve codes and start testing the necessary
circuit in the system while the car is sti ll apart
and repairs can be performed. If you wait until
the entire veh icle is assembled, there may be
30 StarTuned

29. STARTUNED
GENUINE MERCEDES-BENZ PARTS .. , NEARBY
Belmont Palo Alto Walnut Creek
Alabama Pa rk Avenue Motors Mercedes-Benz of Wa lnut Creek
Autobahn Motors
650-637-2333 650-494-0311 925-937-1655
Dothan
Mike Schmitz Automotive Beverly Hills Pasadena West Covina
334-794-6716 Mercedes-Benz of Beverly Hills Rusnak/ Arcadia Mercedes-Benz of West Covina
310-659-2980 626-795-8004 626-859-1200
Hoover
Buena Park Pleasanton
Crown Automobile Colorado
House of Imports Mercedes-Benz of Pleasanton
205-985-4200
714-562-1100 925-463-2525
Colorado Springs
Huntsville Calabasas Riverside Mercedes-Benz of Colorado Springs
Mercedes-Benz of Huntsville Mercedes-Benz of Calabasas Wa lter's Auto Sales & Service, Inc. 719-575-7950
256-837-5752 818-591-2377 951-688-3332
Denver
Carlsbad Rocklin Murray Motor Imports
Mobile Von Hausen 's Motors
McConnell Automotive Hoehn Motors 303-759-3400
760-438-4454 916-630-8877
251-476-4141
Chico Sacramento Littleton
Montgomery Courtesy Motors Auto Center Mercedes-Benz of Sacramento Mercedes-Benz of Littleton
Jack Ingram Motors 530-893-1300 916-924-8000 303-738-7700
334-277-5700
EI Dorado Hills San Diego Westminster
Mercedes-Benz of Eldorado Hills Mercedes-Benz of San Diego Mercedes-Benz of Westminster
Tuscaloosa 916-567-5100 858-279-7202
Leigh Automotive 303-410-7800
205-556-1111 Encino San Francisco
Mercedes-Benz of Encino Mercedes-Benz of San Francisco Connecticut
Alaska 818-788-0234 415-673-2000
San Jose Danbury
Anchorage Escondido Mercedes-Benz of Danbury
Mercedes-Benz of Anchorage Mercedes-Benz of Escondido Beshoff Motorcars
408-239-2300 203-778-6333
907-277-3383 760-745-5000
Fairbanks Fremont San Jose Fairfield
Auto Service Company Fletcher Jones Motor Cars Smythe European Mercedes-Benz of Fairfield
907-456-621 7 510-623-1111 408-983-5200 203-368-6725
Arizona Fresno San Luis Obispo Greenwich
Mercedes-Benz of Fresno Kimba ll Motor Mercedes-Benz of Greenwich
Chandler 559-438-0300 805-543-5752 203-869-2850
Mercedes-Benz of Chandler San Rafael
Glendale Hartford
480-403-3400 R.A.B. Motors
Calstar Motors New Country Motor Cars
Phoenix 818-246-1800 415-454-0582
860-278-2000
Phoenix Motor Santa Barbara
602-264-479 1 Laguna Niguel
Mercedes-Benz of Laguna Niguel Santa Barbara Auto Group New London
949-347-3700 805-682-2000 Carriage House of New London
Phoenix
860-447-3361
Schumacher E uropean Santa Clarita
480-991-115 5 La Jolla
Heinz Gietz Autohaus Mercedes-Benz of Valencia North Haven
Tucson 858-454-7137 661-753-5555 Mercedes-Benz of North Haven
Mercedes-Benz of Tucson 203-239-1313
Los Angeles Santa Monica
520-886-1311 w. 1. Simonson
Downtown L.A. Motors Delaware
213-748-8951 310-526-4700
Arkansas Santa Rosa Milford
Manhattan Beach
Fayetteville Carwell Smothers European I.G. Burton
Mercedes-Benz of Northwest Arkansas 310-303-3500 707-542-4810 302-424-3042
479-521-7281 Modesto Signal Hill Wilmington
Modesto European Mercedes-Benz of Long Beach Mercedes-Benz of Wilmington
Little Rock 209-522-8100
Riverside Motors 562-988-8300 302-995-2211
501-666-945 7 Monterey Stockton
Mercedes-Benz of Monterey Berberian European Motors Florida
California 831 -375-2456 209-944-5511
Clearwater
Anaheim Newport Beach Thousand Oaks Lokey Motor
Mercedes-Benz of Anaheim Fletcher Jones Motor Cars Silver Star A.G. 727-530-1661
714-777-1900 949-718-3000 805-371 -5400
Oakland Coral Gables
Arcadia Torrance
Mercedes-Benz of Oakland Mercedes-Benz of South Bay Mercedes-Benz of Cora l Gables
Rusnak/ Arcadia 305-445-8593
626-447-1117 510-832-6030 310-534-3333
Bakersfield Palm Springs Van Nuys Cutler Bay
Mercedes-Benz of Bakersfield Mercedes-Benz of Palm Springs Keyes European Mercedes-Benz of Cutler Bay
661-836-373 7 760-328-6525 818-461 -3900 305-251-0345
StarTu ned 3 1