DTC Troubleshooting

DTC Troubleshooting: P0979

DTC P0979: Shift Solenoid Valve C (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 if DTC P0979 records.

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

NO - Go to step 4.


4. Select Shift Solenoid C in 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 MENU with the HDS.

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 connector C (22P).

10. Measure the resistance between PCM connector terminal C16 and body ground.

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

NO - Go to step 14.






11. Disconnect shift solenoid harness connector at the transmission housing.

12. Check for continuity between PCM connector terminal C16 and body ground.

Is there continuity?
YES - Repair an short in the wire between PCM connector terminal C16 and the shift solenoid harness connector, then go to step 19.

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 - 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 19.


14. Reconnect all connectors.

15. Update the A/T software in the PCM if it does not have the latest software, PCM Update or substitute a known-good PCM. Reading and Clearing Diagnostic Trouble Codes

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

17. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0979 indicated?
YES - If the PCM was updated, substitute a known-good PCM, Reading and Clearing Diagnostic Trouble Codes then recheck. If the PCM was substituted, go to step 1.

NO - Go to step 18.


18. Monitor the OBD STATUS for P0979 in the DTCs MENU with the HDS.

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 Pending or Confirmed DTCs were indicated on step 17, 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, Reading and Clearing Diagnostic Trouble Codes then recheck. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, return to step 16 and recheck.


19. Clear the DTC with the HDS.

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

21. Check for Pending or Confirmed 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 22.


22. Monitor the OBD STATUS for P0979 in the DTCs MENU with the HDS.

Does the HDS indicate PASSED?
YES - Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated on step 21, 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 20 and recheck.