DTC P0890: TCM Power Relay Sense Circuit Low: Notes

DTC detecting condition: 

Immediately at fault recognition

Trouble symptom: 

Improper gear shifting

Wiring diagram: 

Power supply circuit Ref. to WIRING SYSTEM>POWER SUPPLY CIRCUIT>WIRING DIAGRAM .

Engine electrical system Ref. to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK ECM CONNECTOR  .

   Check the connecting condition of ECM connector.

   Is the ECM connector correctly connected?

   Yes: Go to  2 .

   No: Connect the ECM connector correctly.

2. CHECK HARNESS BETWEEN M/B FUSE AND MAIN RELAY CONNECTOR  .
   1. Turn the ignition switch to OFF.
   2. Measure the voltage between M/B fuse and engine ground.

      Connector & terminal 

      (M/B fuse) No. 26 (+) - Engine ground (-):

   Is the voltage 10 V or more?

   Yes: Repair the harness and connector.

   NOTE: In this case, repair the following item:

   • Short circuit to power supply of harness between M/B fuse and main relay connector
   • Defective main relay

   No: Go to  3 .

3. CHECK HARNESS BETWEEN ECM AND MAIN RELAY CONNECTOR  .
   1. Turn the ignition switch to OFF.
   2. Remove the main relay.
   3. Disconnect the ECM connector.
   4. Measure the resistance between the ECM connector and engine ground.

      Connector & terminal 

      (B134) No. 60 - Engine ground:

   Is the resistance 1 MΩ or more?

   Yes: Repair the poor contact of ECM connector.

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