Test Description
WARNING: This page is about a different variant/trim than selected.
The numbers below refer to the step numbers on the diagnostic table.
- 2: This step tests for a damaged terminal or connector in the TCM connector.
- 4: This step tests for an open/short.
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 |
IMPORTANT:
Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase data.
|
Go to Step 8 | Go to Step 3 |
| 3 |
|
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 replacement, setup, and programming. Is the calibration complete? |
Go to Step 8 | - |
| 7 | Replace the ECM. Refer to Control Module References
for replacement, setup, and programming. Did you complete the replacement? |
Go to Step 8 | - |
| 8 | Perform the following procedure in order to verify the repair:
Has the test run and passed? |
Go to Step 9 | Go to Step 2 |
| 9 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? |
Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK |