2018 Subaru WRX STIFACTORY OEM SERVICE PROCEDURE

Malfunction Indicator Light Does Not Blink

Diagnosis: 

  • The malfunction indicator light circuit is open or shorted.
  • Delivery mode fuse circuit is open.

Trouble symptom: 

Malfunction indicator light does not blink during Inspection Mode.

Wiring diagram: 

Engine Electrical System Ref. to WIRING SYSTEM>Engine Electrical System>WIRING DIAGRAM .

G11574198Courtesy of SUBARU OF AMERICA, INC.
  1. CHECK STATUS OF MALFUNCTION INDICATOR LIGHT  .
    1. Turn the ignition switch to OFF.
    2. Make sure that the delivery mode fuse is removed.
    3. Turn the ignition switch to ON. (Engine OFF)

    Does the malfunction indicator light illuminate?

    Yes: Go to  2.

    No: Repair the malfunction indicator light circuit. Ref. to ENGINE (DIAGNOSTICS) (STI)>Malfunction Indicator Light>MALFUNCTION INDICATOR LIGHT DOES NOT COME ON .

  2. CHECK HARNESS BETWEEN ECM AND DELIVERY MODE FUSE  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from ECM.
    3. Install the delivery mode fuse.
    4. Measure the resistance of harness between ECM connectors.

      Connector & terminal

      (B136) No. 34 - (B136) No. 4:

    Is the resistance less than 1 Ω?

    Yes: Go to  3.

    NO: Repair the harness and connector.

    NOTE: In this case, repair the following item:
    • Open circuit in harness between ECM connector
    • Poor contact of each connector between ECM connector
  3. CHECK FOR POOR CONTACT  .

    Check for poor contact of ECM connector.

    Is there poor contact of ECM connector?

    Yes: Repair the poor contact of ECM connector.

    No: Replace the ECM. Ref. to FUEL INJECTION (FUEL SYSTEMS) (STI)>Engine Control Module (ECM) .

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.