I am having a weird problem with my brake lights. My horn doesn't work, either. All fuses are good.

When you have the headlamps off, if you press the brake pedal, the dash backlights come on, the front turn signal lights come on, and the all the rear lights come on as well as the brake filaments.

When you have the headlamps ON, all the rear lights come on INCLUDING the brake light filaments whether the brakes are actually pressed or not. If you press the brake pedal the rear lights stay unchanged.

What the hell is wrong? Turn signals and brights work fine.

 

oh, this is on a 1990 firebird.

 

bttt...

 

if I have to take apart the steering column, how do I make sure not to set off the air bag?

 

Dude, chill.
You probably have a short somewhere in the wiring harness of the lights. Get yourself a multi-meter and start testing.

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"Only in Britain could it be thought a defect to be “too clever by half.” The probability is that too many people are too stupid by three-quarters."

John Major

 

The horn is fixed. That one was unrelated to this problem (cigarette lighter short).

 

You probably have one of the bulbs in the socket wrong, such that the bulb contact(s) are touching both the tail light and the brake/TS filament contacts in the socket. It's possible that one of the sockets is bad, or the wires are shorted together; but I'd start with the simple things first.

Take the brake light bulbs aout and see if the problem disappears; then if it's OK, start putting them back in one at a time, until you either find the problem or find that you've fixed it.

Remember the first rule for inductve logic (problem solving), known for the last few thousand years as Occam's Razor: "The simplest explanation that fits all the facts is usually the right one".

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"So many Mustangs, so little time..."
ICON Motorsports