WORKHORSE CUSTOM CHASSIS
Service Manual
Automatic Transmission – Allison
2007 W Series
© 2006 Workhorse Custom Chassis — All Rights Reserved
SECTION
7.2
PAGE
393
2007 W Series Chassis
WSM082106
DTC P1688
Step
Action
Yes
No
Schematic Reference: Automatic Transmission Controls Schematics
1
Did you perform the Diagnostic System Check - Vehicle?
Go to Step 2
Go to Diagnostic
System Check - Vehicle
2
1. Install the scan tool.
2. Turn ON the ignition, with the engine OFF.
IMPORTANT:
Before clearing the DTC, use the scan tool in order to record the
Before clearing the DTC, use the scan tool in order to record the
Freeze Frame and Failure Records. The Clear Info function will
Freeze Frame and Failure Records. The Clear Info function will
erase the data.
erase the data.
3. Record the DTC Failure Records.
4. Clear the DTC.
5. Disconnect the 80-way connector at the TCM.
6. Inspect terminal 22 for a pulled back, unlocked, terminal or visible terminal
damage.
Did you find and correct a condition?
Go to Step 8
Go to Step 3
3
1. Disconnect the ECM.
2. Inspect the unmanaged torque signal circuit for a pulled back, unlocked, termi-
nal or visible terminal damage.
Did you find and correct a condition?
Go to Step 8
Go to Step 4
4
Test the unmanaged torque signal circuit between the TCM and ECM for an open or
short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct a condition?
Go to Step 8
Go to Step 5
5
Verify that the ECM has the proper model year software and calibration. This wiring
option is only used with the 8.1L gas engine.
Was the software and calibration current and proper for the engine?
Go to Step 7
Go to Step 6
6
Install the correct ECM calibration. Refer to Control Module References for replace-
ment, setup, and programming.
Is the calibration complete?
Go to Step 8
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