2018 Subaru WRX STIFACTORY OEM SERVICE PROCEDURE

Malfunction Indicator Light Remains Blinking

Diagnosis: 

Delivery mode fuse circuit is shorted to ground.

Trouble symptom: 

Malfunction indicator light blinks when delivery mode fuse is not installed.

Wiring diagram: 

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

G11574198Courtesy of SUBARU OF AMERICA, INC.
  1. CHECK DELIVERY MODE FUSE  .
    1. Make sure that the delivery mode fuse is removed.
    2. Turn the ignition switch to ON.

    Does the malfunction indicator light blink?

    Yes: Go to  2.

    NO: System is normal.

    NOTE: Malfunction indicator light blinks at a cycle of 3 Hz when delivery mode fuse is installed.
  2. CHECK HARNESS BETWEEN ECM AND DELIVERY MODE FUSE  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from ECM.
    3. Measure the resistance between ECM connector and chassis ground.

      Connector & terminal

      (B136) No. 34 - Chassis ground:

    Is the resistance 1 MΩ or more?

    Yes: Replace the ECM. Ref. to FUEL INJECTION (FUEL SYSTEMS) (STI)>Engine Control Module (ECM) .

    No: Repair the short circuit to ground in harness between ECM connector and delivery mode fuse.

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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.

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