DTC Troubleshooting

DTC Troubleshooting: P0979 (22)

DTC P0979: Short in Shift Solenoid Valve C Circuit

NOTE:

- Before you troubleshoot, record all freeze data and any on-board snapshot with the HDS, 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. Turn the ignition switch to ON (II).

2. Clear the DTC with the HDS.

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

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

Is DTC P0979 indicated?
YES - Go to step 8.

NO - Go to step 5.


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

Is a clicking sound heard?
YES - Go to step 6.

NO - Go to step 8.


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

7. Monitor the OBD status for P0979 in the DTCs MENU with the HDS.

Does the HDS indicate FAILED?
YES - Go to step 8.

NO - If the HDS indicates PASSED, intermittent failure, the system is OK at this time. Check for intermittent short to body ground in the wire between shift solenoid valve C and the PCM. If the HDS indicates NOT COMPLETED, go to step 5.


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

9. Jump the SCS line with the HDS.

10. Disconnect PCM connectors B (49P) and C (49P).

11. Measure the resistance between PCM connector terminals C39 and B41 or C41.

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

NO - Go to step 25.






12. Disconnect the shift solenoid wire harness connector.

13. Check for continuity between PCM connector terminals C39 and B41 or C41.

Is there continuity?
YES - Repair short to body ground in the wire between PCM connector terminal C39 and the shift solenoid wire harness connector, then go to step 19.

NO - Go to step 14.






14. 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 15.

NO - Replace shift solenoid valve C or the shift solenoid wire harness, A/T Shift Solenoid Valve Test, Replacement, and Shift Solenoid Wire Harness Replacement then go to step 22.


15. Turn the ignition switch to ON (II).

16. Measure the voltage between PCM connector terminals B3 and B41 or C41.

Is there battery voltage?
YES - Go to step 25.

NO - Go to step 17.






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

18. Check for continuity between PCM connector terminals B41 and body ground, and between C41 and body ground.

Is there continuity?
YES - Check for a blown No. 17 (15 A) fuse in the under-hood fuse/relay box. If the fuse is OK, check the PGM-FI main relay and repair open in the wire between PCM connector terminal B3 and the under-hood fuse/relay box, then go to step 19.

NO - Repair open in the wires between PCM connector terminals B41, C41, and body ground (G101), or repair poor body ground (G101), then go to step 19.






19. Reconnect all connectors.

20. Turn the ignition switch to ON (II).

21. Clear the DTC with the HDS.

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

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

Is DTC P0979 indicated?
YES - Check for intermittent short to body ground in the wire between shift solenoid valve C and the PCM, then go to step 1.

NO - Go to step 24.


24. 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 Temporary DTCs or DTCs were indicated in step 23, go to the indicated DTC's troubleshooting.

NO - If the HDS indicates FAILED, check for intermittent short to body ground in the wire between shift solenoid valve C and the PCM, then go to step 1. If the HDS indicates NOT COMPLETED, go to step 22.


25. Connect PCM connectors B (49P) and C (49P).

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

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

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

Is DTC P0979 indicated?
YES - Check for intermittent short to body ground in the wire between shift solenoid valve C and the PCM. If the PCM was updated, substitute a known-good PCM, How to Troubleshoot A/T Systems then go to step 27. If the PCM was substituted, go to step 1.

NO - Go to step 29.


29. 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 Temporary DTCs or DTCs were indicated in step 28, go to the indicated DTC's troubleshooting.

NO - If the HDS indicates FAILED, check for shift solenoid valve C and the PCM. If the PCM was updated, substitute a known-good PCM, How to Troubleshoot A/T Systems then go to step 27. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, go to step 27.