Brakelights Broke?

September 6, 2006 9:52 AM

1994 Altima - Brake lights always on? What's the deal?

My wife couldn't get her car to start this morning. A bit troublesome as we had recently had the alternator and battery replaced. We thought perhaps she didn't shut the door tight enough and/or left a light on inside the car.

After jumping the car, I noticed that the brake lights were on. The car (manual shift) was in neutral and the parking brake engaged. Even after disengaging the parking brake the lights were on solid (not that the parking brake should affect the rear brake lights, but I wanted to be sure). We finagled with the brake pedal as well thinking it might not be releasing fully, but it seems to be working fine. It's not getting caught on anything and is returning to the normal position.

I checked the fuse, and it appeared fine. I don't have any spare fuses to swap out and check with, unfortunately. They're usually pretty obvious when they're burned out, right? The middle arc-thing should be charred and broken - not the case here. When I removed the fuse, the lights did go out (but of course that means no lights when pressing the brake pedal.)

After letting the car run for a while to charge up the battery, we tried turning off the car - the brake lights were still on... so that was definitely the problem.

She was already late to work so I told her which fuse to remove when she gets to work so it (hopefully) doesn't kill the battery, then can put it back in when she leaves work. Driving with your brakelights always on certainly isn't optimal but driving without them working would be even worse.

So, does anyone have any idea what might cause the brake lights to stay on permanently, even when the car is turned off, and the fuse seems ok?

posted by MarkLark to travel & transportation (7 answers total)

There is probably a switch attached to the brake pedal that triggers the lights, and it has somehow gotten stuck in the closed position. If you can find the switch and replace it (probably cheaply), I bet your lights will work normally again. This page warning: about.com has an electrical diagram for the circuit.
posted by knave at 9:57 AM on September 6, 2006

I had this problem once (different car, though). There was a switch that was closed when you stepped on the brake; it was mounted just above the arm of the brake pedal, somewhere under the steering column. There was a plastic nubbin on the arm that poked into the switch when the pedal was not down; it was this nubbin that forced the switch to open, and the nubbin had snapped off.
posted by adamrice at 10:23 AM on September 6, 2006

Agree with knave and adamrice. This is a pretty easy fix. Just go to an autoparts store, get another one, then dive under the driver's side dashboard, and swap it out.

Hardest part is getting under the dash. I usually end up with my feet on my headrest. It isn't pretty.
posted by QIbHom at 10:36 AM on September 6, 2006

I had this same problem with a different car and it turned out to be what the mechanic called an "occasional short"(I guess it went from occasional to permanent) in the electrical system for the breaklights. In my case, the issue happened to occur over top of the gas tank (Don't EVER buy a GM vehicle... EVER!).

... on preview, I hope adamrice is correct
posted by srw12 at 10:41 AM on September 6, 2006

One thing it could also be (although the previous ideas are probably correct), the spring which holds the pedal up in the upwards position may simply have either worked loose or has stretched somehow. This results in the weight of the brake pedal on the switch full time.
posted by fox_terrier_guy at 10:43 AM on September 6, 2006

Also your current switch may be all right and just need adjustment. If your brake light switch threads in you can try threading it out a bit.
posted by Mitheral at 12:00 PM on September 6, 2006

Thanks all for your help! I'll look into your suggestions tomorrow when the sun is up and I'm ready to stand on my head! :-)
posted by MarkLark at 2:16 PM on September 6, 2006