DTC Troubleshooting

DTC Troubleshooting: P0979

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. Reading and Clearing Diagnostic Trouble Codes

- 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. Test-drive the vehicle in 1st gear, with the shift lever in D for at least 1 second.

4. Check for Pending or Confirmed 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. Test-drive the vehicle in 1st gear, with the shift lever 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 connector B (49P).

11. Measure the resistance between PCM connector terminal B21 and body ground.

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

NO - Go to step 24.






12. Disconnect the shift solenoid wire harness connector.

13. Check for continuity between PCM connector terminal B21 and body ground.

Is there continuity?
YES - Repair short to body ground in the wire between PCM connector terminal B21 and the shift solenoid wire harness connector, then go to step 18.

NO - Go to step 14.






14. Inspect shift solenoid valve C and the shift solenoid wire harness. 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 either shift solenoid valve C or the shift solenoid wire harness, A/T Shift Solenoid Valve Test, Replacement, and Shift Solenoid Wire Harness Replacement whichever failed the test, then go to step 21.


15. Disconnect PCM connector A (49P).

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

17. Measure the voltage between PCM connector terminal A1 and body ground.

Is there battery voltage?
YES - Go to step 24.

NO - Check for a blown fuse No. 10 (10 A) in the driver's under-dash fuse/relay box. If the fuse is OK, repair open in the wire between PCM connector terminal A1 and the driver's under-dash fuse/relay box, then go to step 18.






18. Reconnect all connectors.

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

20. Clear the DTC with the HDS.

21. Start the engine with the shift lever in P, and wait for at least 1 second. Then test-drive the vehicle in 1st gear, with the shift lever in D for at least 1 second.

22. Check for Pending or Confirmed 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 23.


23. 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 in step 22, 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 21.


24. Reconnect all connectors.

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

26. Start the engine with the shift lever in P, and wait for at least 1 second. Then test-drive the vehicle in 1st gear, with the shift lever in D for at least 1 second.

27. Check for Pending or Confirmed 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, Reading and Clearing Diagnostic Trouble Codes then go to step 26. If the PCM was substituted, go to step 1.

NO - Go to step 28.


28. 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 in step 27, 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. If the PCM was updated, substitute a known-good PCM, Reading and Clearing Diagnostic Trouble Codes then go to step 26. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, go to step 26.