Brake lights constantly lit on tail lights?
May 3rd, 2008, 1:17 PM
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Brake lights constantly lit on tail lights?
My right brake light and turn signal went out in my Deali. I replaced the fuses and they work again, but when the brake fuse is in my brake lights on both my tail lights and constantly on like someone is pressing the brakes, but my 3rd brake light isn't on. Anyone have any idea what's wrong??? I have to keep my fuse out just so I can drive my car cause they stay on even when they key is out of the ignition.
May 3rd, 2008, 1:47 PM
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RE: Brake lights constantly lit on tail lights?
I had an old car where I was able to replace what was called a brake switch. It was nothing more than a button that was depressed when the brake pedal touched it. I have no idea if cars still use these simple switches, nothing seems to be simple anymore. But if you have a broken switch, or maybe even a bad brake relay (if there is such a thing), possibly this could be the solution to your problem. Electrical issues are the devil, to be sure!
May 3rd, 2008, 2:10 PM
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RE: Brake lights constantly lit on tail lights?
Not the brake switch. The new gm trucks have a different brake switch. When you press on the brake it puls a bracket that's mounted to it sending a signal to light the brakes. I unplugged this, and the lights are still on so I dunno... Thanks for the help though
May 3rd, 2008, 2:44 PM
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RE: Brake lights constantly lit on tail lights?
Is there such a thing as a brake relay in the fusebox(s). The manual should show it. Just a thought.
[IMG]local://upfiles/13808/D2CE21F8FCA643CCAE22E26EBCAE795F.jpg[/IMG]
[IMG]local://upfiles/13808/D2CE21F8FCA643CCAE22E26EBCAE795F.jpg[/IMG]
May 3rd, 2008, 6:11 PM
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RE: Brake lights constantly lit on tail lights?
The power for the brakes comes from the BCM. With key off, try unplugging the brown connector at the BCM. If the brakes go out, then the fault is with the bcm, or brake switch harness leading to the bcm. If they don't go out, then there is a short to B+ somewhere to the back. The brake circuits are pins 1 and 2 in the brown connector
May 3rd, 2008, 7:30 PM
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RE: Brake lights constantly lit on tail lights?
Where is the brake control module? And if there is something wrong with that, what would I need go replace. Same thing with the pins in he circuit, how would I fix the problem? I guess I still don't know what to do if it's one of those problems. Thanks, this will be a good start and help 
May 3rd, 2008, 8:53 PM
#7
RE: Brake lights constantly lit on tail lights?
BCM = Body Control Module. It is under the drivers side of the dash
The brake switch that is being used in new vehicles, are normally closed switches. Which means the contacts are closed when the pedal is noy pressed, and the contacts open when the pedal is pressed.
By disconnecting the switch, you made the BCM think the the pedal is depressed. Disconnect the switch, and place a jumper wire into pins c and d. orang\white and purple. See if the lights are still on. If not, you have a bad switch.
The brake switch that is being used in new vehicles, are normally closed switches. Which means the contacts are closed when the pedal is noy pressed, and the contacts open when the pedal is pressed.
By disconnecting the switch, you made the BCM think the the pedal is depressed. Disconnect the switch, and place a jumper wire into pins c and d. orang\white and purple. See if the lights are still on. If not, you have a bad switch.
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May 4th, 2008, 9:24 AM
#9
RE: Brake lights constantly lit on tail lights?
Shark, he said that the CHMSL doesn't come on at all. Good point though...Patry, does the 3rd light work when you hit the brakes?
I am starting to think there is a problem in the BCM, and just thought of something, Try d\c the battery for a minute in hopes that the BCM will "reset" itself and turn off your brake lights
I am starting to think there is a problem in the BCM, and just thought of something, Try d\c the battery for a minute in hopes that the BCM will "reset" itself and turn off your brake lights