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. Start the engine, and run 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 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. Start the engine, and run 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 - 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), B (24P), and C (22P).
10. Measure the resistance between PCM connector terminals C16 and A3 or B15.
Is there less than 12 Ohms?
YES - Go to step 11.
NO - Go to step 18.
11. Disconnect shift solenoid harness connector at the transmission housing.
12. Check for continuity between PCM connector terminals C16 and A3 or B15.
Is there continuity?
YES - Repair short in the wire between PCM connector terminal C16 and the shift solenoid harness connector, then go to step 23.
NO - Go to step 13.
13. Inspect shift solenoid valve C.
Is shift solenoid valve C OK?
YES - Go to step 14.
NO - Replace shift solenoid valve C or the shift solenoid harness, then go to step 23.
14. Turn the ignition switch to ON (II).
15. Measure the voltage between PCM connector terminals A4 and A3 or B15.
Is there battery voltage?
YES - Go to step 18.
NO - Go to step 16.
16. Turn the ignition switch to LOCK (0).
17. Check for continuity between PCM connector terminals A3 and body ground, and between B15 and body ground.
Is there continuity?
YES - Check for blown No. 23 fuse in the driver's under-dash fuse/relay box. If the fuse is OK, repair open in the wire between PCM connector terminal A4 and the driver's under-dash fuse/relay box, then go to step 23.
NO - Repair open in the wires between PCM connector terminals A3, B15, and ground (G101, G102), or repair poor ground (G101, G102), then go to step 23.
18. Reconnect all connectors.
19. Update the A/T software in the PCM if it does not have the latest software, or substitute a known-good PCM.
20. Start the engine in P, wait for at least 1 second, then test-drive the vehicle in D. Run the vehicle in 3rd or 4th gear at least 1 second, then slow down to a stop. Put the shift lever into N or P.
21. 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 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 - 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 21, 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 20 and recheck.
23. Clear the DTC with the HDS.
24. Start the engine in P, wait for at least 1 second, then test-drive the vehicle in D. Run the vehicle in 3rd or 4th gear at least 1 second, then slow down to a stop. Put the shift lever into N or P.
25. 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 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 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 24 and recheck.