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, and review General Troubleshooting Information. How to Troubleshoot A/T Systems
- 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, and test-drive the vehicle in 1st gear in D for at least 1 second.
3. Check that DTC P0979 recurs.
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, and test-drive the vehicle in 1st gear in D 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 - If the HDS indicates PASSED, intermittent failure, the system is OK at this time. Check the SHC wire for an 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 C (49P).
10. Measure the resistance between PCM connector terminals C39 and C41.
Is there less than 12 Ohms?
YES - Go to step 11.
NO - Go to step 19.
11. Disconnect the shift solenoid harness connector.
12. Check for continuity between PCM connector terminals C39 and C41.
Is there continuity?
YES - Repair short in the wire between PCM connector terminal C39 and the shift solenoid harness connector, then go to step 24.
NO - Go to step 13.
13. Inspect shift solenoid valve C. A/T Shift Solenoid Valve Test/Replacement
Is shift solenoid valve C OK?
YES - Go to step 14.
NO - Replace shift solenoid valve C or the shift solenoid harness, A/T Shift Solenoid Valve Test/Replacement then go to step 24.
14. Disconnect PCM connector B (49P).
15. Turn the ignition switch to ON (II).
16. Measure the voltage between PCM connector terminals B3 and C41.
Is there battery voltage?
YES - Go to step 19.
NO - Go to step 17.
17. Turn the ignition switch to LOCK (0).
18. Check for continuity between PCM connector terminals B41 and body ground, and between C41 and body ground.
Is there continuity?
YES - Check for a blown No. 8 (15 A) fuse in the under-hood fuse/relay box. If the fuse is OK, check the PGM-FI main relay and repair open in the wire between PCM connector terminal B3 and the under-hood fuse/relay box, then go to step 24.
NO - Repair open in the wires between PCM connector terminals B41, C41, and body ground (G101), or repair poor body ground (G101), then go to step 24.
19. Connect PCM connectors B (49P) and C (49P).
20. Update the A/T software in the PCM if it does not have the latest software, PCM Update or substitute a known-good PCM. Initial Inspection and Diagnostic Overview
21. Start the engine in P, and wait for at least 1 second, then test-drive the vehicle in D. Drive the vehicle in 1st gear for at least 1 second, then slow down to a stop.
22. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0979 indicated?
YES - If the PCM was updated, substitute a known-good PCM, Initial Inspection and Diagnostic Overview then recheck. If the PCM was substituted, go to step 1.
NO - Go to step 23.
23. 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 22, go to the indicated DTC's troubleshooting.
NO - If the HDS indicates FAILED, check for poor connections and loose terminals between shift solenoid valve C and the PCM. If the PCM was updated, substitute a known-good PCM, Initial Inspection and Diagnostic Overview then recheck. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, go to step 21.
24. Reconnect all connectors.
25. Clear the DTC with the HDS.
26. Start the engine in P, and wait for at least 1 second, then test-drive the vehicle in D. Drive the vehicle in 1st gear for at least 1 second, then slow down to a stop.
27. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0979 indicated?
YES - Check for poor connections and loose terminals between shift solenoid valve C and the PCM, then go to step 1.
NO - Go to step 28.
28. 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 27, go to the indicated DTC's troubleshooting.
NO - If the HDS indicates FAILED, check for poor connections and loose terminals between shift solenoid valve C and the PCM, then go to step 1. If the HDS indicates NOT COMPLETED, go to step 26.