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Home >> Subaru >> 2010 >> Legacy Premium, Standard >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 24 (Automatic Transmission - Diagnostics) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0957 Backup Light Relay Circuit Low >> Wiring Diagram

DTC P0957 Backup Light Relay Circuit Low: Wiring Diagram

WARNING: This page is about a different variant/trim than selected.
Fig 1: Backup Light Relay Circuit Low - Wiring Diagram
G06654836Courtesy of SUBARU OF AMERICA, INC.
DIAGNOSIS PROCEDURE

Step Check Yes No
1 CHECK DTC OF TCM.  Is DTC of Transmission Range Sensor Circuit (PRNDL Input) detected? Perform the diagnosis according to DTC. Go to step .
2 CHECK HARNESS CONNECTOR BETWEEN TCM AND BACK-UP LIGHT RELAY. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connector from TCM and back-up light relay.
  3. Measure the resistance of harness between TCM connector and back-up light relay connector.

    Connector & terminal 

    (B54) No. 13 - (B499) No. 1: 

Is the resistance less than 1 Ω? Go to step . Repair the open circuit of harness or poor contact of connector between TCM connector and transmission connector.
3 CHECK HARNESS CONNECTOR BETWEEN TCM AND TRANSMISSION. 
Measure the resistance of harness between TCM connector and chassis ground.
Connector & terminal 
(B54) No. 13 - Chassis ground: 
Is the resistance 1 MΩ or more? Go to step . Repair the short circuit of harness between TCM connector and transmission connector.
4 CHECK OUTPUT SIGNAL OF TCM. 
  1. Turn the ignition switch to ON.
  2. Shift the select lever to "P" range.
  3. Measure the voltage between TCM connector and chassis ground.

    Connector & terminal 

    (B54) No. 13 (+) - Chassis ground (-): 

Is the voltage 8 V or more? Go to step . Replace the TCM. Ref. to TRANSMISSION CONTROL MODULE (TCM) .
5 CHECK OUTPUT SIGNAL OF TCM. 
  1. Set the select lever to "R" range.
  2. Measure the voltage between TCM connector and chassis ground.

    Connector & terminal 

    (B54) No. 13 (+) - Chassis ground (-): 

Is the voltage 1 V or less? Go to step . Replace the TCM. Ref. to TRANSMISSION CONTROL MODULE (TCM) .
6 CHECK INPUT VOLTAGE FOR BACK-UP LIGHT RELAY. 
Measure the voltage between back-up light relay and chassis ground.
Is the voltage 10 - 13 V? Replace the backup light relay. Check open or short circuit of harness between fuse (No. 18) and backup light relay.