DTC Troubleshooting

DTC Troubleshooting: P0979 (22)

DTC P0979: Shift Solenoid Valve C Circuit (Short)

NOTE:

- Before you troubleshoot, record all freeze data and any on-board snapshot, and review General Troubleshooting Information. How to Troubleshoot A/T Systems

- This code is caused by an electrical circuit problem and cannot be caused by a mechanical problem in the transmission.

1. Clear the DTC with the HDS.

2. Start the engine, and run the vehicle in 1st gear in D for at least 1 second.

3. Check that DTC P0979 recurs.

Is DTC P0979 indicated?
YES - Go to step 7.

NO - Go to step 4.


4. Select Shift Solenoid C in the Miscellaneous Test Menu, and test shift solenoid valve C with the HDS.

Is a clicking sound heard?
YES - Go to step 5.

NO - Go to step 7.


5. Start the engine, and run the vehicle in 1st gear in D for at least 1 second.

6. Monitor the OBD STATUS for P0979 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail.

Does the HDS indicate FAILED?
YES - Go to step 7.

NO - Intermittent failure, the system is OK at this time. Check the SHC wire for an intermittent short between shift solenoid valve C and the PCM. If the HDS indicates NOT COMPLETED, return to step 4 and recheck.


7. Turn the ignition switch to LOCK (0).

8. Jump the SCS line with the HDS.

9. Disconnect PCM connectors B (44P) and C (44P).

10. Measure the resistance between PCM connector terminals B20 and C40 or C44.

Is there less than 12 Ohms?
YES - Go to step 11.

NO - Connect PCM connectors B (44P) and C (44P), then go to step 14.






11. Disconnect the shift solenoid harness connector.

12. Check for continuity between PCM connector terminals B20 and C40 or C44.

Is there continuity?
YES - Repair short in the wire between PCM connector terminal B20 and the shift solenoid harness connector, then go to step 18.

NO - Go to step 13.






13. Inspect shift solenoid valve C. A/T Shift Solenoid Valve Test, Replacement, and Shift Solenoid Wire Harness Replacement

Is shift solenoid valve C OK?
YES - Connect all connectors, then go to step 14.

NO - Replace shift solenoid valve C or the shift solenoid harness, A/T Shift Solenoid Valve Test, Replacement, and Shift Solenoid Wire Harness Replacement then go to step 18.


14. Update the A/T software in the PCM if it does not have the latest software, PCM Update or substitute a known-good PCM. How to Troubleshoot A/T Systems

15. Start the engine in P, wait for at least 1 second, then test-drive the vehicle in D. Run the vehicle in 1st gear for at least 1 second, then slow down to a stop.

16. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0979 indicated?
YES - If the PCM was updated, substitute a known-good PCM, How to Troubleshoot A/T Systems then recheck. If the PCM was substituted, go to step 1.

NO - Go to step 17.


17. Monitor the OBD STATUS for P0979 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail.

Does the HDS indicate PASSED?
YES - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM. Service and Repair If any other DTCs were indicated on step 16, go to the indicated DTC's troubleshooting.

NO - Check for poor connections and loose terminals at shift solenoid valve C and the PCM. If the PCM was updated, substitute a known-good PCM, How to Troubleshoot A/T Systems then recheck. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, return to step 15 and recheck.


18. Clear the DTC with the HDS.

19. Start the engine in P, wait for at least 1 second, then test-drive the vehicle in D. Run the vehicle in 1st gear for at least 1 second, then slow down to a stop.

20. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0979 indicated?
YES - Check for poor connections and loose terminals at shift solenoid valve C and the PCM, then go to step 1.

NO - Go to step 21.


21. Monitor the OBD STATUS for P0979 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail.

Does the HDS indicate PASSED?
YES - Troubleshooting is complete. If any other DTCs were indicated on step 20, go to the indicated DTC's troubleshooting.

NO - Check for poor connections and loose terminals at shift solenoid valve C and the PCM, then go to step 1. If the HDS indicates NOT COMPLETED, return to step 19 and recheck.