DTC Troubleshooting
DTC P0979: Short in Shift Solenoid Valve C CircuitNOTE:
^ Before you troubleshoot, record all freeze data and any on-board snapshot, and review General Troubleshooting Information.
^ 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. Test-drive the vehicle in D until reaching 3rd gear. Then, drive in 3rd gear for at least 1 second, and 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 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. Test-drive the vehicle in D until reaching 3rd gear. Then, drive in 3rd gear for at least 1 second, and slow down to a stop.
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 SH C wire for an intermittent short 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 connectors A (31P) and C (22P).
10. Measure the resistance between PCM connector terminals C2 and A8 or A9.
Is there less than 12 ohms?
YES - Go to step 11.
NO - Go to step 14.
11. Disconnect the shift solenoid harness connector at the shift solenoid valve cover.
12. Check for continuity between PCM connector terminals C2 and A8 or A9.
Is there continuity?
YES - Repair short in the wire between PCM connector terminal C2 and the shift solenoid harness connector, then go to step 19.
NO - Go to step 13.
13. Inspect shift solenoid valve C.
Is shift solenoid valve C OK?
YES - If the shift solenoid harness is replaced because of shift solenoid valve C test result, go to step 19. If the harness is OK, go to step 14.
NO - Replace shift solenoid valve C, then go to step 19.
14. Reconnect all connectors.
15. Update the A/T software in the PCM if it does not have the latest software, or substitute a known-good PCM.
16. Test-drive the vehicle in D until reaching 3rd gear. Then slow down to a stop. Shift to P, and wait for at least 1 second.
17. Check for DTC(s) in the DTCs/Freeze Data in A/T Mode Menu 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 18.
18. 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. If any other DTCs were indicated on step 17, go to the indicated DTC's troubleshooting.
NO - Check for poor connections and loose terminals at 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 16 and recheck.
19. Clear the DTC with the HDS.
20. Test-drive the vehicle in D until reaching 3rd gear. Then slow down to a stop. Shift to P, and wait for at least 1 second.
21. Check for DTC(s) in the DTCs/Freeze Data in A/T Mode Menu with the HDS.
Is DTC P0979 indicated?
YES - Check for poor connections and loose terminals at 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/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 21, go to the indicated DTC's troubleshooting.
NO - Check for poor connections and loose terminals at shift solenoid valve C and the PCM, then go to step 1. If the HDS indicates NOT COMPLETED, return to step 20 and recheck.