Frieghtliner xc chassis Brake Light Problem
when I put my brakes on the brake lights come on and wont go off. If I unplug the rear taillight/brake light harness they go off and stay off until the next time i put the brakes on.I have replaced bo...
Forum Discussion
Are the brake lights the correct ones (oem spec)? Do the lights go off when you pull the brake light fuse - could be a short somewhere? Ditto when you disconnect either pressure switch wire? Also wondering why there would be 2 pressure switches? What harness did you disconnect, location, any other wires? Bad brake petal switch is possible, have you disconnected it's wiring only? Bad ground is a possibility.
Anothebr possibility is a blown fuse that supplies power to whatever controls the lights, relays or electronics.
What is the voltage at the chassis battery terminals? Ditto lights and any where else you can measure.
When looking for this type of problem ALWAYS connect the voltmeter to a good clean frame ground as a open or partially open ground wire can be misleading. You want to measure 12V+ (close to the battery voltage) on the positive wire and 0V on the negative. Measure a common + and - wire to the lights or each and every one. A DC clamp on ammeter to measure amps can be helpful and every DIY RVer should have one anyway.
Anothebr possibility is a blown fuse that supplies power to whatever controls the lights, relays or electronics.
What is the voltage at the chassis battery terminals? Ditto lights and any where else you can measure.
When looking for this type of problem ALWAYS connect the voltmeter to a good clean frame ground as a open or partially open ground wire can be misleading. You want to measure 12V+ (close to the battery voltage) on the positive wire and 0V on the negative. Measure a common + and - wire to the lights or each and every one. A DC clamp on ammeter to measure amps can be helpful and every DIY RVer should have one anyway.
