DTC Troubleshooting
DTC Troubleshooting: P0979 (22)
DTC P0979:
Shift Solenoid Valve C (Short)
NOTE:
- Before you troubleshoot, record all freeze data and any on-board snapshot with the HDS, and review the General Troubleshooting Information How to Troubleshoot the A/T System.
- 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 in P, and run the vehicle in 1st gear in D for at least 1 second.
3. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0979 indicated?
YES -
Go to step 7.
NO -
Go to step 4.
4. 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 5.
NO -
Go to step 7.
5. Start the engine in P, 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 -
If the HDS indicates PASSED, intermittent failure, the system is OK at this time. Check the SHC wire for intermittent short to body ground between shift solenoid valve C and the PCM. If the HDS indicates NOT COMPLETED, go to step 4.
7. Turn the ignition switch to LOCK (0).
8. Jump the SCS line with the HDS.
9. Disconnect PCM connector B (44P).
10. Measure the resistance between PCM connector terminal B20 and body ground.
Is there less than 12 Ohms?
YES -
Go to step 11.
NO -
Connect PCM connector B (44P), then go to step 14.
11. Disconnect the shift solenoid wire harness connector.
12. Check for continuity between PCM connector terminal B20 and body ground.
Is there continuity?
YES -
Repair a short to body ground in the wire between PCM connector terminal B20 and the shift solenoid wire harness connector, then go to step 18.
NO -
Go to step 13.
13. Inspect shift solenoid valve C 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 wire harness Shift Solenoid Valve Test, Replacement, and Shift Solenoid Wire Harness Replacement, then go to step 20.
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.
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. Slow down, and stop the wheels.
16. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0979 indicated?
YES -
If the PCM was updated, substitute a known-good PCM, then go to step 15. If the PCM was substituted, go to step 1.
NO -
Go to step 17.
17. 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 16, 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, then go to step 15. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, go to step 15.
18. Reconnect all connectors.
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 for at least 1 second. Slow down, and stop the wheels.
21. 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 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 in step 21, 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 20.