DTC Troubleshooting: P0979 (22-3)

DTC P0979:

Short in Shift Solenoid Valve C Circuit

• 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 1st gear in the D position for more than 1 second.

3.	Check that DTC P0979 recurs. Is DTC P0979 indicated? YES - Go to 7. NO - Go to 4.

4.	Choose Shift Solenoid C in Miscellaneous Test Menu, and test the shift solenoid valve C with the HDS. Is the system normal? YES - Go to 5. NO - Go to 7.

5.	7-position transmission: Test-drive the vehicle in 3rd gear in the D3 position for more than 1 second. 5-position transmission: Test-drive the vehicle in 3rd gear in the S position for more than 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 result indicate FAILED? YES - Go to 7. NO - Intermittent failure, the system is OK at this time. Check the SH C (GRN) wire for an intermittent short to ground between shift solenoid valve C and the PCM. If the tester indicates NOT COMPLETED, return to 4 and recheck.n

7.	Turn the ignition switch OFF.

8.	Jump the SCS line with the HDS.

9.	Disconnect PCM connectors B (44P) and C (44P).

10.

Measure resistance between PCM connector terminals B20 and C40 or C44.   Is there less than 12 W? YES - Go to 11. NO - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original  PCM.n

11.	Disconnect the shift solenoid harness connector.

12.	Check for continuity between PCM connector terminals B20 and C40 or C44.   Is there continuity? YES - Repair short to ground in the wire between PCM connector terminal B20 and the shift solenoid harness connector, then go to 14. NO - Go to 13.

13.

Inspect shift solenoid valve C. Is shift solenoid valve C OK? YES - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original  PCM.n NO - Replace shift solenoid valve C or shift solenoid harness, then go to 14.

14.	Clear the DTC with the HDS.

15.	7-position transmission: Test-drive the vehicle in 3rd gear in the D3 position for more than 1 second. 5-position transmission: Test-drive the vehicle in 3rd gear in the S position for more than 1 second.

16.	Monitor the OBD status for P0979 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail. Does the result indicate PASSED? YES - Troubleshooting is complete.n NO - Return to 7 and recheck.