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 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. Turn the ignition switch to ON (II).
2. Clear the DTC with the HDS.
3. Start the engine in P, and wait for at least 1 second. Then test-drive the vehicle in 1st gear 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. Start the engine, and test-drive 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 an 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 C (49P).
11. Measure the resistance between PCM connector terminal C39 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 C39 and body ground.
Is there continuity?
YES -
Repair a short to body ground in the wire between PCM connector terminal C39 and the shift solenoid wire harness connector, then go to step 18.
NO -
Go to step 14.
14. Inspect shift solenoid valve C Shift Solenoid Valve Test, Replacement, And Shift Solenoid Wire Harness Replacement (A/T).
Is shift solenoid valve C OK?
YES -
Go to step 15.
NO -
Replace shift solenoid valve C or the shift solenoid wire harness Shift Solenoid Valve Test, Replacement, And Shift Solenoid Wire Harness Replacement (A/T), then go to step 21.
15. Disconnect PCM connector B (49P).
16. Turn the ignition switch to ON (II).
17. Measure the voltage between PCM connector terminal B2 and body ground.
Is there battery voltage?
YES -
Go to step 24.
NO -
Check for a blown No.7 (15 A) fuse in the driver's under-dash fuse/relay box. If the fuse is blown, replace it. If it blows again, repair short in the No. 7 (15A) driver's under-dash fuse circuit. If the fuse OK, repair open in the wires between PCM connector terminal B2 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 in P, wait for at least 1 second. Then test-drive the vehicle in 1st gear for at least 1 second. Slow down, and stop the wheels.
22. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0979 indicated?
YES -
Check for an 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 an 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.
26. Start the engine in P, wait for at least 1 second. Then test-drive the vehicle in 1st gear for at least 1 second. Slow down, and stop the wheels.
27. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0979 indicated?
YES -
Check for an 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 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 shift solenoid valve C and the PCM. If the PCM was updated, substitute a known-good PCM, then go to step 26. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, go to step 26.