DTC P2127: Throttle/Pedal Position Sensor/Switch "E" Circuit Low: Notes

DTC detecting condition: 

Immediately at fault recognition

Trouble symptom: 

• Improper idling
• Poor driving performance

Wiring diagram: 

Engine Electrical System Ref. to WIRING SYSTEM>Engine Electrical System>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK HARNESS BETWEEN ECM AND ACCELERATOR PEDAL POSITION SENSOR CONNECTOR  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from ECM.
   3. Disconnect the connector from the accelerator pedal position sensor.
   4. Measure the resistance between ECM connector and chassis ground.

      Connector & terminal 

      (B135) No. 22 - Chassis ground:

      (B135) No. 31 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes:  Go to  2

   No:  Repair the short circuit to ground in harness between ECM connector and accelerator pedal position sensor connector.

2. CHECK SHORT CIRCUIT INSIDE THE ECM  .
   1. Connect the connector to ECM.
   2. Measure the resistance between accelerator pedal position sensor connector and chassis ground.

      Connector & terminal 

      (B315) No. 3 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes:  Replace the accelerator pedal. Ref. to SPEED CONTROL SYSTEMS(STI)>Accelerator Pedal .

   No:  Repair the short circuit to ground in harness between ECM connector and accelerator pedal position sensor connector. Replace the ECM if defective. Ref. to FUEL INJECTION (FUEL SYSTEMS) (STI)>Engine Control Module (ECM) .