2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Break lights not working

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Old Aug 5, 2005 | 12:08 PM
  #1  
pinkfloyd's Avatar
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From: leawood,kansas
Break lights not working

I had my friend test the switch at the pedal and even when the break pedal is pressed the switch still shows some resistance. He also pulled the relay thingy out of cpu to test it, but we cant find a way to test it even after looking through the factory service manual and the Haynes manual. Any help in trying to fix my break lights would be great.

Thanks
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Old Aug 5, 2005 | 03:23 PM
  #2  
SureShot's Avatar
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From: Orange Park FL (near Jax)
The pedal switch must close to 0 ohms when you step on the pedal.

I'd try some spray contact cleaner in the switch.
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Old Aug 5, 2005 | 09:07 PM
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From: leawood,kansas
will do. anyone know of a way to test the relay which also controles the horn so it seems
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Old Aug 5, 2005 | 09:51 PM
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bump, I don't think the resistance in the switch is because of the contacts, when I tested it they were clean.
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Old Aug 5, 2005 | 10:01 PM
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From: Rohnert Park CA
Originally Posted by pinkfloyd
will do. anyone know of a way to test the relay which also controles the horn so it seems
There is no relay and the horn relay does not control the brakes.

Jumper the brake switch lead to the brake light lead at the bottom of the CPU.

If it works the CPU's brake light circuit board needs replacing (and I do have rebuilt ones on my website).

If it does not work then you either have a blown fuse (most likely) unplugged brake light switch, bad brake light switch, or disconnected wires running to the rear.
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Old Aug 6, 2005 | 09:48 AM
  #6  
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BTW Pink, of course it's not working, it's a break light, breaking is what it does! (it's brake not break)
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Old Aug 6, 2005 | 05:33 PM
  #7  
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From: Auckland, New Zealand
So they're not break lights, they're broken lights!

Things like brake light circuits are very easy to troubleshoot. Look in the FSM wiring digram and you'll see the circuit is very simple and each item in the circuit is easily tested to find the faulty one. The circuit is:

60A BTN fuse (powers half the car) -- 20A STOP fuse (protects brake lights and horn circuits) -- brake pedal switch -- warning relay (in CPU) -- bulbs

I'm assuming since you were digging in the CPU you have an S4? It helps if you tell us this, or at least put it in your profile.

If the horn works, it's not the fuse, If it doesn't, it is. If the fuse is okay, press on the brake pedal and use a DMM or test light to check for 12V on each side of the switch and CPU.
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Old Aug 6, 2005 | 07:20 PM
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Originally Posted by NZConvertible
So they're not break lights, they're broken lights!

Things like brake light circuits are very easy to troubleshoot. Look in the FSM wiring digram and you'll see the circuit is very simple and each item in the circuit is easily tested to find the faulty one. The circuit is:

60A BTN fuse (powers half the car) -- 20A STOP fuse (protects brake lights and horn circuits) -- brake pedal switch -- warning relay (in CPU) -- bulbs

I'm assuming since you were digging in the CPU you have an S4? It helps if you tell us this, or at least put it in your profile.

If the horn works, it's not the fuse, If it doesn't, it is. If the fuse is okay, press on the brake pedal and use a DMM or test light to check for 12V on each side of the switch and CPU.
DUH! I feel like a moron, I was checking for continuance accross the circuit while the switch was depressed.
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Old Aug 6, 2005 | 09:19 PM
  #9  
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From: leawood,kansas
we got it fixed now. It was pluged into the wrong connector and the fuse was blown. I must have blown the fuse messing around with it because that was the first thing i checked.

thanks a lot guys
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