DTC B2284: Brake Signal Correlation

DTC detecting condition: 

When the brake signal transmitted via solid line and the brake signal transmitted via CAN communication line do not match.

Trouble symptom: 

Wiring diagram: 

Stop light system Ref. to WIRING SYSTEM>Stop Light System>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK LAN SYSTEM  .

   Inspect LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>Basic Diagnostic Procedure>PROCEDURE

   Is the check result OK?

   Yes: Go to  2

   No: Perform the inspection according to the diagnosis for LAN system.

2. CHECK CURRENT DATA  .

   Check the current data display of «Keyless Access with Push Button Start» using Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>Read Current Data 

   • «Stop light SW»

   Is DTC displayed normally according to the brake pedal operation?

   Yes: Go to  3

   No: Check the stop light system.

3. CHECK CURRENT DATA  .

   Confirm the current data display of «Body Control» using Subaru Select Monitor. Ref. to KEYLESS ACCESS WITH PUSH BUTTON START SYSTEM (DIAGNOSTICS)>Read Current Data 

   • «Stop light SW»

   Is DTC displayed normally according to the brake pedal operation?

   Yes: Go to  4

   No: Check body integrated unit Ref. to BODY CONTROL SYSTEM (DIAGNOSTICS)>Basic Diagnostic Procedure>PROCEDURE and the stop light switch circuit.

4. CHECK FUSE  .

   Check the fuse. Ref. to SECURITY AND LOCKS>Relay and Fuse

   Is the check result OK?

   Yes: Go to  5

   No: Replace the fuse. When the replaced fuse is blown immediately, check the power supply circuit for short-circuited.

5. CHECK HARNESS  .
   1. Disconnect the keyless access CONTROL MODULE connector.
   2. Using a tester, measure the voltage between the keyless access CONTROL MODULE connector and chassis ground.

      Connector & terminal 

      (B572) No. 2 (+) - Chassis ground (-):

   Is the voltage 9.5 - 16 V?

   Yes: Go to  6

   No: Check the power supply circuit.

6. CHECK HARNESS (OPEN CIRCUIT)  .

   Using a tester, measure the resistance between the keyless access CONTROL MODULE connector and chassis ground.

   Connector & terminal 

   (B572) No. 11 - Chassis ground:

   Is the resistance less than 1 Ω?

   Yes: Go to  7

   No: Repair or replace the open circuit of harness.

7. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Disconnect the stop light switch connector.
   2. Using a tester, measure the resistance between the keyless access CONTROL MODULE connector and stop light switch connector.

      Connector & terminal 

      (B572) No. 18 - (B65) No. 2:

   Is the resistance less than 1 Ω?

   Yes: Go to  8

   No: Repair or replace the open circuit of harness.

8. CHECK HARNESS (GROUND SHORT CIRCUIT)  .

   Using a tester, measure the resistance between the keyless access CONTROL MODULE connector and chassis ground.

   Connector & terminal 

   (B572) No. 18 - Chassis ground:

   Is the resistance 10 kΩ or more?

   Yes: Go to  9

   No: Repair or replace the short circuit of the harness.

9. CHECK HARNESS  .

   Using a tester, measure the voltage between the keyless access CONTROL MODULE connector and chassis ground when the brake pedal is depressed.

   Connector & terminal 

   (B572) No. 18 (+) - Chassis ground (-):

   Does the voltage change as follows? Brake pedal not depressed: 1 V or less → Brake pedal depressed: 11 - 14 V

   Yes: Replace the keyless access CONTROL MODULE. Ref. to SECURITY AND LOCKS>Keyless Access CONTROL MODULE >REMOVAL

   No: Check the power supply circuit of stop light switch.