On-Board Diagnostic System Check

This test determines if the Transmission itself or its inputs or outputs connections or sensors are failing.

If you do not have a "Scan Tool" (TECH 1), use the "CHECK TRANS" Indicator Codes.
Displaying and Reading Trouble Codes


If you do have a "Scan Tool" (TECH 1):

1. Connect the TECH 1. Refer to Scan Tool Testing / Connecting TECH 1.
Scan Tool Testing
2. Turn on the Ignition but not the Engine.
3. Push "F2" on TECH 1 to see the Diagnostic Trouble Code (DTC).
4. If you have a DTC, write down all the code numbers and check the appropriate Trouble Code Chart.
5. If you do not have a DTC:
a. Do the "CHECK TRANS" Check.
Transmission and Drivetrain





b. If it is flashing and the flash is 0.2 seconds "ON" and 0.2 seconds "OFF", this means that you should have a DTC stored. Recheck and if you find the same problem, replace the TCM.

3. IF the "CHECK TRANS" indicator is not flashing, refer to Diagnosis Without DTC Set.
Diagnosis When DTC Is Not Set