DTC P0971 Pressure Control Solenoid "C" Control Circuit High: Notes

DTC detecting condition: 

Immediately at fault recognition

Trouble symptom: 

• Tight corner braking phenomenon occurs.
• Drivability getting worse.

Wiring diagram: 

• Non-turbo model

  CVT control system Ref. to WIRING SYSTEM>CVT Control System>WIRING DIAGRAM>NON-TURBO MODEL .

  Fig 1: Pressure Control Solenoid (C) Control Circuit High System Wiring Diagram (Non-Turbo Model)

  Courtesy of SUBARU OF AMERICA, INC.
• Turbo model

  CVT control system Ref. to WIRING SYSTEM>CVT Control System>WIRING DIAGRAM>TURBO MODEL .

1. CHECK HARNESS. 
   1. Turn the ignition switch to OFF.
   2. Disconnect the TCM connector.
   3. Disconnect the transmission connector.
   4. Measure the resistance between TCM connector and transmission connectors.

      Connector & terminal 

      Non-turbo model 

      (B54) No. 48 - (B11) No. 8:

      Turbo model 

      (B54) No. 48 - (B11) No. 4:

   Is the resistance less than 1 Ω?

   • Yes  : Go to 2. 
   • No  : Repair the open circuit of harness.
2. CHECK HARNESS. 
   1. Turn the ignition switch to ON.
   2. Measure the voltage between TCM connector and chassis ground.

      Connector & terminal 

      (B54) No. 48 (+) - Chassis ground (-):

   Is the voltage approx. 0 V?

   • Yes  : Go to 3. 
   • No  : Repair the short circuit of harness.
3. CHECK AWD SOLENOID. 

   Measure the resistance between transmission connector and transmission body.

   Connector & terminal 

   Non-turbo model 

   (T4) No. 8 - Transmission body:

   Turbo model 

   (T4) No. 4 - Transmission body:

   Is the resistance approximately 2 - 4.5 Ω? (when cold)

   • Yes  : Check for poor contact of connector, and if no fault is found, replace the TCM. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION(TR580)>Transmission Control Module (TCM) . Ref. to CONTINUOUSLY VARIABLE TRANSMISSION(TR690)>Transmission Control Module (TCM) .
   • No  : Go to 4. 
4. CHECK HARNESS INSIDE TRANSMISSION. 
   CAUTION: Start work after ATF cools down.
   1. Remove the following parts.
      • Transmission valve cover (non-turbo model)
      • Transmission oil pan (turbo model)
   2. Check for the harness pinch, damage.

   Is there any fault in the harness?

   • Yes  : Replace the transmission harness.
   • No  : Go to 5. 
5. CHECK HARNESS INSIDE TRANSMISSION. 
   1. Disconnect the control valve body connector.
   2. Turn the ignition switch to ON.
   3. Measure the voltage between transmission connector and transmission body.

      Connector & terminal 

      Non-turbo model 

      (T4) No. 8 (+) - Transmission body (-):

      Turbo model 

      (T4) No. 4 (+) - Transmission body (-):

   Is the voltage approx. 0 V?

   • Yes  : Replace the control valve body. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION(TR580)>Control Valve Body . Ref. to CONTINUOUSLY VARIABLE TRANSMISSION(TR690)>Control Valve Body .
   • No  : Replace the transmission harness.