DTC P0979 (6-Speed A/T)

DTC P0979  : Shift Solenoid Valve C (Short)

NOTE: 

• Before you troubleshoot, review the General Troubleshooting Information - Refer to: 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.
• If DTC P0979 is stored in the PCM, the transmission does not shift to 2nd or 5th gear because of the fail-safe function.

DTC (A/T)

1. Problem verification

   - 1. Turn the vehicle to the ON mode.

   - 2. Clear the DTC with the HDS.

   - 3. Start the engine in P, and wait for at least 1 second.

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

   DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
   P0979 Shift Solenoid Valve C (Short)

   Is DTC P0979 indicated?

   YES 

   The failure is duplicated. Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Check for poor connections and loose terminals between shift solenoid valve C and the PCM. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot.

2. Fuse check

   - 1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Check the following fuse.

   Fuse	No. C31 (7.5 A)
   Location	Under-dash fuse/relay box

   Is the fuse OK?

   YES 

   The fuse is OK. Go to step 3.

   NO 

   Replace the No. C31 (7.5 A) fuse, and recheck. If the fuse blows again, repair a short to ground on the No. C31 (7.5 A) fuse circuit, and recheck.

3. Open wire check (IG1 VB SOL line)

   - 1. Jump the SCS line with the HDS, and wait more than 1 minute.

   - 2. Disconnect the following connector.

   PCM connector A (51P)

   - 3. Turn the vehicle to the ON mode.

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

   Test condition	Vehicle ON mode
   	PCM connector A (51P): disconnected
   Test point 1	PCM connector A (51P) No. 1 - Refer to: PCM Connector for Inputs and Outputs (16-20 6-Speed A/T) .
   Test point 2	Body ground

   Is there battery voltage?

   YES 

   The IG1 VB SOL Wire is OK. Go to step 4.

   NO 

   Repair an open in the IG1 VB SOL wire between the PCM and the No. C31 (7.5 A) fuse in the under-dash fuse/relay box.

4. Determine possible failure area (shift solenoid valve C, others)

   - 1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Reconnect PCM connector A (51P).

   - 3. Disconnect the following connector.

   Shift solenoid valve C 2P connector

   - 4. Turn the vehicle to the ON mode.

   - 5. Clear the DTC with the HDS.

   - 6. Start the engine in P, and wait for at least 1 second.

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

   DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
   P0979 Shift Solenoid Valve C (Short)

   Is DTC P0979 indicated?

   YES 

   Shift solenoid valve C is OK. Go to step 5.

   NO 

   Replace shift solenoid valve C .

5. Shorted wire check (SHC line)

   - 1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Jump the SCS line with the HDS, and wait more than 1 minute.

   - 3. Disconnect the following connector.

   PCM connector B (51P)

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

   Test condition	Vehicle OFF (LOCK) mode
   	Shift solenoid valve C 2P connector: disconnected
   	PCM connector B (51P): disconnected
   Test point 1	PCM connector B (51P) No. 3 - Refer to: PCM Connector for Inputs and Outputs (16-20 6-Speed A/T) .
   Test point 2	Body ground

   Is there continuity?

   YES 

   Repair a short to ground in the SHC wire between shift solenoid valve C and the PCM.

   NO 

   The SHC wire is OK. Replace the PCM - Refer to: PCM Removal and Installation (6-Speed A/T, 16-18 9-Speed A/T) .