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DTC P0122: Throttle/Pedal Position Sensor/Switch "A" Circuit Low: Notes

DTC detecting condition:

Immediately at fault recognition

Trouble symptom:

Improper idling
Engine stalls.
Poor driving performance

CAUTION: Use the check board when measuring the ECM terminal voltage and resistance. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>GENERAL DESCRIPTION>PREPARATION TOOL>HOW TO USE CHECK BOARD .

NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

Wiring diagram:

Engine Electrical System Ref. to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM .

G13202419

Courtesy of SUBARU OF AMERICA, INC.

CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL CONNECTOR (SHORT TO GROUND).
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
3. Disconnect the connectors from electronic throttle control.
4. Measure the resistance between the ECM connector and engine ground.
  Connector and terminal.
  
  (E158) No. 34 - Engine ground:
  
  (E158) No. 49 - Engine ground:
Is the resistance 1 MΩ or more?

Yes : Go to 2.

No : Repair the ground short circuit of harness between ECM connector and electronic throttle control connector.
CHECK SHORT CIRCUIT INSIDE ECM.
1. Connect the connector to ECM.
2. Measure the resistance between electronic throttle control connector and engine ground.
  Connector and terminal.
  
  (E57) No. 1 - Engine ground:
Is the resistance 1 MΩ or more?

Yes : Replace the electronic throttle control. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>THROTTLE BODY .

No : Repair the ground short circuit of harness between ECM connector and electronic throttle control connector. When there is no ground short circuit in the harness, replace the ECM. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>ENGINE CONTROL MODULE (ECM) .