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.
- Some wire colors vary according to the model year, and are indicated with an asterisk as follows:
- *(1): '09 - 10 models
1. Clear the DTC with the HDS.
2. Start the engine, and test-drive the vehicle:
- Seven-position transmission: Drive the vehicle in D3, and let the transmission shift through all three gears. Drive the vehicle in 3rd gear for at least 1 second, then slow down to a stop.
- Five-position transmission: Drive the vehicle in 1st thru 3rd gears in the sequential sport shift mode in S. Drive the vehicle in 3rd gear for at least 1 second, then slow down to a stop.
3. Check that DTC P0979 recurs.
Is DTC P0979 indicated?
YES -
Go to step 7.
NO -
Go to step 4.
4. Select Shift Solenoid 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, and test-drive the vehicle:
- Seven-position transmission: Drive the vehicle in D3, and let the transmission shift through all three gears, then slow down to a stop. Shift into P, and wait for at least 1 second.
- Five-position transmission: Drive the vehicle in 1st thru 3rd gears in the sequential sport shift mode in S, then slow down to a stop. Shift into P, and wait for at least 1 second.
6. Monitor the OBD status for P0979 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail.
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 to ground 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 B (49P).
10. Measure the resistance between PCM connector terminal B21 and body ground.
Is there less than 12 Ohms?
YES -
Go to step 11.
NO -
Go to step 17.
11. Disconnect the shift solenoid harness connector.
12. Check for continuity between PCM connector terminal B21 and body ground.
Is there continuity?
YES -
Repair a short in the wire between PCM connector terminal B21 and the shift solenoid harness connector, then go to step 22.
NO -
Go to step 13.
13. Inspect shift solenoid valve C Testing and Inspection.
Is shift solenoid valve C OK?
YES -
Go to step 14.
NO -
Replace shift solenoid valve C or the shift solenoid harness Shift Solenoid Valve And Shift Solenoid Wire Harness Replacement, then go to step 22.
14. Disconnect PCM connector A (49P).
15. Turn the ignition switch to ON (II).
16. Measure the voltage between PCM connector terminal A1 and body ground.
Is there battery voltage?
YES -
Go to step 17.
NO -
Check for a blown No. 7 (10 A) fuse in the under-hood fuse/relay box. If the fuse is OK, repair an open or a short in the wire between PCM connector terminal A1 and the under-hood fuse/relay box, then go to step 22.
17. Connect PCM connectors.
18. Update the A/T software in the PCM if it does not have the latest software ECM/PCM Update, or substitute a known-good PCM.
19. Start the engine, and test-drive the vehicle:
- Seven-position transmission: Drive the vehicle in D3, and let the transmission shift through all three gears, then slow down to a stop. Shift into P, and wait for at least 1 second.
- Five-position transmission: Drive the vehicle in 1st thru 3rd gears in the sequential sport shift mode in S, then slow down to a stop. Shift into P, and wait for at least 1 second.
20. 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 recheck. If the PCM was substituted, go to step 1.
NO -
Go to step 21.
21. Monitor the OBD status for P0979 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail.
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 DTCs were indicated on step 20, go to the indicated DTC's troubleshooting.
NO -
Check for an intermittent short in the wire between shift solenoid valve C and the PCM. If the PCM was updated, substitute a known-good PCM, then recheck. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, return to step 19 and recheck.
22. Reconnect all connectors.
23. Clear the DTC with the HDS.
24. Start the engine, and test-drive the vehicle:
- Seven-position transmission: Drive the vehicle in D3, and let the transmission shift through all three gears, then slow down to a stop. Shift into P, and wait for at least 1 second.
- Five-position transmission: Drive the vehicle in 1st thru 3rd gears in the sequential sport shift mode in S, then slow down to a stop. Shift into P, and wait for at least 1 second.
25. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0979 indicated?
YES -
Check for an intermittent short in the wire between shift solenoid valve C and the PCM, then go to step 1.
NO -
Go to step 26.
26. Monitor the OBD status for P0979 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail.
Does the HDS indicate PASSED?
YES -
Troubleshooting is complete. If any other DTCs were indicated on step 25, go to the indicated DTC's troubleshooting.
NO -
Check for an intermittent short in the wire between shift solenoid valve C and the PCM, then go to step 1. If the HDS indicates NOT COMPLETED, return to step 24 and recheck.