DTC Troubleshooting

Control System DTCs

DTC Troubleshooting: P0979

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.

1. Problem verification (DTC check):

Problem verification (DTC check)
-1. Turn the ignition switch to ON (II).

-2. Clear the DTC with the HDS.

-3. Test-drive the vehicle in 3rd gear for at least 1 second.

-4. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0979 indicated?
-YES- The failure is duplicated. Go to step 4.
-NO- Go to step 2.

2. Shift solenoid valve C operation check:

Shift solenoid valve C operation check
-1. Select Shift Solenoid valve C in the Miscellaneous Test Menu, and test shift solenoid valve B with the HDS.

Is a clicking sound heard?
-YES- Shift solenoid valve C is OK. Go to step 3.
-NO- Go to step 4.

3. Problem verification (OBD STATUS check):

Problem verification (OBD STATUS check)
-1. Test-drive the vehicle in 1st gear with the shift lever in D, for at least 1 second.

-2. Monitor the OBD STATUS for P0979 in the DTCs MENU with the HDS.

Does the HDS indicate FAILED?
-YES- The failure is duplicated. Go to step 4.
-NO- If the HDS indicates PASSED, intermittent failure, the system is OK at this time. Check for an intermittent short to ground in the wire between shift solenoid valve C and the PCM. If the HDS indicates NOT COMPLETED, test-drive again.

4. Shift solenoid valve C internal resistance check:

Shift solenoid valve C internal resistance check
-1. Turn the ignition switch to LOCK (0).

-2. Jump the SCS line with the HDS.

-3. Disconnect the following connector.





-4. Measure the resistance between test points 1 and 2.









Is there less than 13.8 Ohms?
-YES- Go to step 5.
-NO- Shift solenoid valve C is OK. Update the PCM if it does not have the latest software ECM/PCM Update, or substitute a known-good PCM Service and Repair, then do the repair verification.

5. Shorted wire check (SH_C line):

Shorted wire check (SH_C line)
-1. Disconnect the following connector.





-2. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- Repair a short to ground in the SH_C wire between the shift solenoid wire harness and the PCM, then do the repair verification.
-NO- The SH_C wire is OK. Go to step 6.

6. Shift solenoid valve C check:

Shift solenoid valve C check
-1. Test shift solenoid valve C Testing and Inspection.

Is shift solenoid valve C OK?
-YES- Shift solenoid valve C is OK. Replace the shift solenoid wire harness Shift Solenoid Wire Harness Removal and Installation (A/T), then do the repair verification.
-NO- Replace shift solenoid valve C Shift Solenoid Valve Removal/Installation, then do the repair verification.

Repair verification (OBD STATUS check):

-1. Reconnect all connectors.

-2. Turn the ignition switch to ON (II).

-3. Clear the DTC with the HDS.

-4. Start the engine with the shift lever in P, and wait for at least 1 second. Then test-drive the vehicle in 3rd gear for at least 1 second.

-5. Monitor the OBD STATUS for P0979 in the DTCs MENU with the HDS.

Does the HDS indicate PASSED, FAILED, or NOT COMPLETED?
-PASSED- Troubleshooting is complete. If the PCM was substituted, replace the original PCM Service and Repair. Check for other DTC after this troubleshooting. If any other Pending or Confirmed DTCs were indicated, go to the indicated DTC's troubleshooting.
-FAILED- Go to step 1 and recheck. If the PCM was updated, substitute a known-good PCM Service and Repair, and check the OBD STATUS again.
-NOT COMPLETED- Meet the test condition, and check the OBD STATUS again.