Brake Warning Light Does Not Go Off

Detecting condition: 

• Brake warning light circuit is shorted.
• Defective sensor/connector
• Defective CAN communication

Trouble symptom: 

Brake warning light does not go off after starting the engine.

Wiring diagram: 

Parking brake/brake fluid level warning light system Ref. to WIRING SYSTEM>PARKING BRAKE/BRAKE FLUID LEVEL WARNING LIGHT SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK INSTALLATION OF VDCCM&H/U CONNECTOR  .
   1. Turn the ignition switch to OFF.
   2. Check that the VDCCM&H/U connector is inserted until it is locked by clamp.

   Is the connector firmly inserted?

   Yes:  Go to  2.

   No:  Insert the VDCCM&H/U connector until it is locked by clamp.

2. READ DTC  .

   Read the DTC using Subaru Select Monitor. Ref. to BRAKE CONTROL (DIAGNOSTICS)>Diagnostic Trouble Code (DTC) .

   Is DTC displayed?

   Yes:  Perform the diagnosis according to the DTC. Ref. to BRAKE CONTROL (DIAGNOSTICS)>Diagnostic Trouble Code (DTC)>LIST .

   No:  Go to  3.

3. CHECK LAN SYSTEM  .

   Check the LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .

   Is the check result OK?

   Yes:  Go to  4.

   No:  Perform the diagnosis for LAN system.

4. CHECK BRAKE FLUID AMOUNT  .

   Check the amount of brake fluid in the reservoir tank of master cylinder.

   Does the level of the brake fluid amount fall between the lines of "MAX" and "MIN"?

   Yes:  Go to  5.

   No:  Replenish brake fluid to the specified value.

5. CHECK BRAKE FLUID LEVEL SWITCH  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the brake fluid level switch connector (B16) from master cylinder.
   3. Measure the resistance between master cylinder terminals.

      Terminals 

      No. 1 - No. 2:

   Is the resistance 1 MΩ or more?

   Yes:  Go to  6.

   No:  Replace the master cylinder. Ref. to BRAKE>MASTER CYLINDER .

6. CHECK GROUND SHORT OF HARNESS  .
   1. Disconnect the connector from VDCCM.
   2. Measure the resistance between VDCCM connector and chassis ground.

      Connector & terminal 

      (B310) No. 27 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes:  Go to  7.

   No:  Repair the harness between VDCCM and brake fluid level switch.

7. CHECK COMBINATION METER  .

   Check the combination meter. Ref. to INSTRUMENTATION/DRIVER INFO>Combination Meter System>OPERATION>SELF-DIAGNOSIS DISPLAY MODE .

   Is the check result OK?

   Yes:  Replace the VDCCM&H/U. Ref. to VEHICLE DYNAMICS CONTROL (VDC)>VDC CONTROL MODULE AND HYDRAULIC CONTROL UNIT (VDCCM&H/U) .

   No:  Replace the combination meter. Ref. to INSTRUMENTATION/DRIVER INFO>COMBINATION METER .