1) Toyota vehicles use a "two-trip" detection logic for some transmission solenoid and ratio codes, requiring a problem to occur on two consecutive drive cycles before setting a code. 2) A scan tool's "Check Mode" feature can bypass this two-trip logic, treating these codes as one-trip faults and making problems easier to diagnose. 3) To use Check Mode, technicians select the option while the engine is off, start the vehicle, and drive it until a code appears, narrowing what the vehicle monitors to quickly find issues.

1. PLAYING WITH FIRE
What a Trip!
Understanding Toyota’s Shift by Jon Rodriguez
www.atra.com
Solenoid Performance Codes
H
ere’s our scenario; An OBD-
II Toyota, let’s say a 1999
Camry, comes into your shop
with the MIL lit. You follow standard
test procedures: You connect your scan
tool, record any codes, clear the codes,
and test drive the vehicle to see how
long it takes the code to come back.
For this example we’re going to
say the code is the common P0770 —
Shift Solenoid E Malfunction. Toyota’s
criteria for setting this code is:
• Lockup doesn’t occur when
driving in lockup range (nor-
mal driving at 80 km/h (50
mph), or…
• Lockup remains on when it
should be off.
So we clear the codes and drive the
Camry on the freeway to see how long
it takes this code to set. After a 10-mile
test drive, the MIL doesn’t come back
on and you’re scratching your head.
You tell the customer the code is
What’s a Trip?
A trip as defined by
Toyota is: “An engine-
operation drive cycle
that contains all of the
necessary conditions
for a particular test
(monitor) to be
performed.”
12 GEARS December 2009

3. What a Trip!
intermittent and to drive the car until it until it detects the condition again dur- Check Mode, all diagnostic
comes back. The next day the customer ing the next trip. Then it sets the code codes will be erased instantly.
pulls back into the shop with the MIL in memory and lights the MIL. This
on and P0770 in memory. Why did it happens only after the second trip is Now that you understand Check
set with the customer, but not during complete, which means the MIL won’t Mode, you’re ready to use it. Follow
your test drive? What a trip! Actually, light until you turn the key off after the these steps whenever an OBD-II Toyota
two trips. second trip and then restart the engine. comes into your shop with the MIL lit.
This situation is a common call to This is why the ratio or solenoid 1. Check codes using your
the ATRA HotLine. In this edition of performance codes take so long to set. Toyota-compatible scan tool.
Playing with Fire, we’re going to cover The problem has to occur on two con- 2. Record any codes in memory.
Toyota’s two-trip logic codes and how secutive trips, and then doesn’t appear 3. With the key on, engine off
to take advantage of your scan tool’s until the engine is started for the third (KOEO), select Check Mode
features to diagnose them quickly and time. from your scan tool options.
correctly. Does this mean that you have to (Remember that some tools
drive the vehicle all this time to diag- will have a different name
What’s a Trip? nose the problem? Absolutely not! or location for Check Mode.
A trip as defined by Toyota is: Consult your scan tool’s man-
“An engine-operation drive cycle that Check Mode ual for more information.)
contains all of the necessary conditions Toyota realized that this type of 4. Once you’ve selected Check
for a particular test (monitor) to be logic can take too much time to diag- Mode, the MIL will flash rap-
performed.” This is different than the nose properly, so a little-known diag- idly.
SAE definition that we’re all accustom nostic feature was built into Toyota’s 5. Start the engine. Does the MIL
to but we’re going to use it so we can ECM: Check Mode. turn off?
view the following test from the Toyota Most scan tools have an option for • No: Repair the condition that
perspective. Toyotas called Check Mode. Sometimes set the code.
For a trip to take place, the vehicle you may see it called by another name • Yes: Switch the scan tool to
must start cold, warm up normally to (Sensitivity Mode, Test Mode or in the data mode.
at least 160ºF (71ºC). Once you go case of the Ease Scan tool, a square 6. Confirm that the Check Mode
through the necessary driving maneu- button with a checkmark; figures 1 Parameter Identification (PID)
vers you’ll need to turn off the key in and 2). indicates on or yes.
order to complete the trip. Check Mode does two things to aid 7. Drive the vehicle until the MIL
Here’s where Toyota’s trip logic in diagnoses: lights.
gets a little tricky. Solenoid electrical 1. Turns all two-trip logic codes 8. Confirm and write down the
codes (P0753, P0758, P0763, P0768, into one-trip logic codes, recurring code.
P1818) have one-trip detection logic: regardless of what system is 9. Turn the engine off for at least
When the computer detects an elec- being tested. ten seconds to disable Check
trical problem with the solenoid, it 2. Narrows the parameters the Mode.
immediately lights the MIL, sets a code computer uses to detect faults so Important: All codes that set
in memory, and records Freeze Frame that it’ll set codes more easily. during Check Mode will be
data. During the same cycle, the com- erased automatically when
puter will test the solenoid electrically A few important issues about you turn the engine off.
eight times before setting the code. This Check Mode: 10. Follow the manufacturer’s
usually takes only a few seconds if the • Check Mode clears existing diagnostic tree for repairing
problem is obvious (open or shorted current, pending, and freeze the fault.
wire, bad solenoid, etc.) frame codes, so make sure
Solenoid performance codes, or you write down any codes By using the Check Mode option,
better termed, ratio codes (P0750, in memory before initializing you can solve the mystery of inter-
P0755, P0760, P0765, P1815), have Check Mode. mittent codes quickly and accurately.
two-trip detection logic: When the com- • Two-trip EVAP codes will Check Mode also works well when test
puter first detects the problem, the code remain two-trip codes in driving a freshly rebuilt transmission
is sent to the pending section of the Check Mode. to make sure that a code isn’t going to
computer and the MIL doesn’t light… • Check Mode disables the come up a day or two after customer
yet. The only way to find these codes is Misfire Monitor. delivery. Neither the customer nor the
to access the Pending Codes with your • You must record any codes boss like that scenario!
scan tool. that set in Check Mode before Special thanks to Roger at Payless
Once the computer detects a prob- turning the ignition or scan Transmission and Clutch in Fresno, CA
lem the first time, it stops monitoring tool off. When you turn the for his contribution to this article.
that particular system during the cur- scan tool or ignition switch
rent trip. It won’t actually set a code off, or when you disable
14 GEARS December 2009