Diagnostic Procedure with Cancel Code: 12: Wiring Diagram

WARNING: This page is about a different car, the 2012 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Stop Light & Brake Switch Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE CHART

Step	Check	Yes	No
1 CHECK STOP LIGHT & BRAKE SWITCH. Check the stop light & brake switch. < Ref. to STOP LIGHT & BRAKE SWITCH . >	Is the stop light & brake switch and installation position OK?	Go to step 2 .	Replace the stop light & brake switch. Or adjust the installation position.
2 CHECK STOP LIGHT & BRAKE SWITCH CIRCUIT. Turn the ignition switch to OFF. Disconnect the stop light & brake switch harness connector. Turn the ignition switch to ON. Measure the voltage between harness connector terminal and chassis ground. Connector & terminal (B65) No. 2 (+) - Chassis ground (-):	Is the voltage 10 V or more?	Go to step 3 .	Check fuse No. 8 (in fuse & relay box). Check for open or short in the harness between stop light & brake switch and fuse & relay box.
3 CHECK STOP LIGHT & BRAKE SWITCH CIRCUIT. Measure the voltage between harness connector terminal and chassis ground. Connector & terminal (B65) No. 4 (+) - Chassis ground (-):	Is the voltage 10 V or more?	Go to step 4 .	Check fuse No. 4 (in fuse & relay box). Check for open or short in the harness between stop lights brake switch and fuse & relay box.
4 CHECK STOP LIGHT & BRAKE SWITCH CIRCUIT. Turn the ignition switch to OFF. Disconnect the harness connector of ECM. Measure the resistance between ECM harness connector terminal and stop light & brake switch harness connector terminal. Connector & terminal (B136) No. 15 - (B65) No. 1: (B136) No. 3 - (B65) No. 3:	Is the resistance less than 10 Ω?	Replace the ECM. < Ref. to ENGINE CONTROL MODULE (ECM) . >	Repair the harness.