DTC P2102: Throttle Actuator "A" Control Motor Circuit Low: Notes

DTC detecting condition: 

Immediately at fault recognition

Trouble symptom: 

• Improper idling
• Poor driving performance
• Engine stalls.
  CAUTION:

  • After servicing or replacing faulty parts, perform Clear Memory Mode Refer to ENGINE (DIAGNOSTICS) (EXCEPT FOR STI)>CLEAR MEMORY MODE>OPERATION , and inspection mode Refer to ENGINE (DIAGNOSTICS) (EXCEPT FOR STI)>INSPECTION MODE>PROCEDURE ..
  • Use the check board when measuring the ECM terminal voltage and resistance.

Wiring diagram: 

Engine Electrical System Refer to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK ELECTRONIC THROTTLE CONTROL RELAY. 
   1. Turn the ignition switch to OFF.
   2. Remove the electronic throttle control relay.
   3. Connect the battery to terminals No. 16 and No. 17 of electronic throttle control relay.
   4. Measure the resistance between electronic throttle control relay terminals.

      Terminals 

      No. 14 - No. 15:

   Is the resistance less than 1 Ω?

   Yes:  Go to  2.

   No:  Replace the electronic throttle control relay. Refer to FUEL INJECTION (FUEL SYSTEMS) (EXCEPT FOR STI)>ELECTRONIC THROTTLE CONTROL RELAY .

2. CHECK POWER SUPPLY OF ELECTRONIC THROTTLE CONTROL RELAY. 

   Measure the voltage between electronic throttle control relay connector and chassis ground.

   Connector & terminal 

   (B225) No. 15 (+) - Chassis ground (-):

   Is the voltage 10 V or more?

   Yes:  Go to  3.

   No:  Repair the open or short to ground in the power supply circuit.

3. CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL RELAY CONNECTOR. 
   1. Disconnect the connector from ECM.
   2. Turn the ignition switch to ON.
   3. Measure the voltage between electronic throttle control relay connector and chassis ground.

      Connector & terminal 

      (B225) No. 17 (+) - Chassis ground (-):

   Is the voltage 10 V or more?

   Yes:  Repair the short circuit to power in the harness between ECM connector and electronic throttle control relay connector.

   No:  Go to  4.

4. CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL RELAY CONNECTOR. 
   1. Turn the ignition switch to OFF.
   2. Measure the resistance between electronic throttle control relay connector and chassis ground.

      Connector & terminal 

      (B225) No. 14 - Chassis ground:

      (B225) No. 17 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes:  Go to  5.

   No:  Repair the short circuit to ground in harness between ECM connector and electronic throttle control relay connector.

5. CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL RELAY CONNECTOR. 

   Measure the resistance between ECM connector and electronic throttle control relay connector.

   Connector & terminal 

   (B134) No. 39 - (B225) No. 17:

   (B134) No. 11 - (B225) No. 14:

   Is the resistance less than 1 Ω?

   Yes:  Repair the poor contact of ECM connector.

   No:  Repair the open circuit in harness between ECM connector and electronic throttle control relay connector.