Operation CHARM: Car repair manuals for everyone.

M/T

DTC P1121 - NEUTRAL POSITION SWITCH CIRCUIT HIGH INPUT

DTC DETECTING CONDITION:
- Two consecutive driving cycles with fault

TROUBLE SYMPTOM:
- Erroneous idling

CAUTION: After repair or replacement of faulty parts, conduct CLEAR MEMORY MODE and INSPECTION MODE. Refer to How To Clear Diagnostic Trouble Codes.

Wiring Diagram:





WIRING DIAGRAM

10BX1: CHECK INPUT SIGNAL FOR ECM.

1. Turn ignition switch to ON.

Connector & Terminal - [(B135) No.26 (+) - Chassis ground (-)]:





2. Measure voltage between ECM and chassis ground.

CHECK: Is the voltage more than 10 V in neutral position?

YES: Go to step 10BX2.

NO: Go to step 10BX4.

10BX2: CHECK INPUT SIGNAL FOR ECM

Connector & Terminal - [(B135) No.26 (+) - Chassis ground (-)]:





Measure voltage between ECM and chassis ground

CHECK: Is the voltage less than 1 V in other positions?

YES: Go to step 10BX3.

NO: Go to step 10BX4.

10BX3: CHECK POOR CONTACT.
Check poor contact in ECM connector.

CHECK: Is there poor contact in ECM connector?

YES: Repair poor contact in ECM connector.

NO: Contact with Subaru of America (SOA) service.

NOTE:
Inspection by Subaru of America's DTM is required, because probable cause is deterioration of multiple parts.

10BX4: CHECK NEUTRAL POSITION SWITCH.

Connector & Terminal - [(T2) No.1 - No.2]:





Measure resistance between transmission harness connector terminals.

CHECK: Is the resistance less than 1 Ohm in other positions?

YES: Go to step 10BX5.

NO: Repair open circuit in transmission harness or replace neutral position switch.

10BX5: CHECK HARNESS BETWEEN ECM AND NEUTRAL POSITION SWITCH CONNECTOR.

1. Disconnect connector from ECM.

Connector & Terminal - [(B135) No.26 - (B25) No.1]:





2. Measure resistance of harness between ECM and transmission harness connector.

CHECK: Is the resistance less than 1 Ohm?

YES: Go to step 10BX6.

NO: Repair open circuit in harness between ECM and transmission harness connector.

10BX6: CHECK HARNESS BETWEEN ECM AND NEUTRAL POSITION SWITCH CONNECTOR.

Connector & Terminal - [(B25) No.2 - Engine Ground]:





Measure resistance of harness between transmission harness connector and engine ground.

CHECK: Is the resistance less than 5 Ohms?

YES: Go to step 10BX7.

NO: Repair harness and connector.

NOTE: In this case, repair the following:
- Open circuit in harness between transmission harness connector and engine grounding terminal
- Poor contact in coupling connector (B22)

10BX7: CHECK POOR CONTACT
Check poor contact in transmission harness connector.

CHECK: Is there poor contact in transmission harness connector?

YES: Repair poor contact in transmission harness connector.

NO: Contact with Subaru of America (SOA) service.

NOTE: Inspection by Subaru of America's DTM is required, because probable deterioration of multiple parts.