Operation CHARM: Car repair manuals for everyone.

Brake Switch Signal Circuit Troubleshooting

Brake Switch Signal Circuit Troubleshooting

1. Check the brake lights.
Are the brake lights on without pressing the brake pedal?

YES - Inspect the brake switch adjustment.

NO - Go to step 2.

2. Press the brake pedal.
Do the brake lights come on?

YES - Go to step 3.

NO - Go to step 4.





3. Measure voltage between ECM connector terminals A32 and B20 with the brake pedal pressed.
Is there battery voltage?

YES - The brake switch signal is OK.

NO - Repair open in the wire between the ECM (A32) and the brake switch.

4. Inspect the No.6 (10 A) fuse in the under-hood fuse/relay box.
Is the fuse OK?

YES - Repair open in the wire between the brake switch and the No.6 (10 A) fuse. Inspect the brake switch.

NO - Repair short in the wire between the ECM(A32) and the No.6 (10 A) fuse. Replace the No.6 (10 A) fuse.