Bad ground or is it normal?

[jak133]

Hey all, was putting taillights back on after paint and while checking them with key turned to on position (engine not running) pressed brake pedal and radio cut out but lights work. With engine running radio does not cut out, whats going on here?

[baz]

sure sounds like a bad ground

[jak133]

sure sounds like a bad ground

Thanks Baz, electrics are not my specialty. Where do I start ignition, brake system, or lights?

[markandson]

One other possibility. If you have a new radio it may have low voltage protection circuitry. Without the car running you may cause a low voltage condition when the brake lights come on, just a thought.

[jak133]

One other possibility. If you have a new radio it may have low voltage protection circuitry. Without the car running you may cause a low voltage condition when the brake lights come on, just a thought.

Never thought about that, it is new radio and everything seems to work fine.

[First opel 1981]

Never thought about that, it is new radio and everything seems to work fine.

To test this theory you can hook up a battery charger (or jumper cables) to your battery and try again.

[JimVonBaden]

Old thread, but keep in mind that with new paint you need to make sure your grounds are making good contact. Turning on the ignition can provide an alternate ground, and make it look like the brake lights are working, but then with the parking lights on you have no brake lights again.

Jim