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Cadillac Technician
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Low brake fluid level?
Sticking park brake switch?
Binding lever causing incomplete release of the lever?
Sticking cables, binding hardware, faulty IPC, certain ABS DTCs, the list goes on.
 

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Usually the switch that controls the red brake lamp from the park brake pedal is just a set of contacts with a single wire connector.

It's usually way up towards the top back of the pedal assembly.
Try unplugging the single wire connector on the switch then recheck the light.
If it's out, you probably have a bent or otherwise damaged switch.

There are still more possibilities.
 

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Discussion Starter · #6 ·
hmmmm... so today I took off the plastic cover underneath the dash to take a look at the switch... I unplugged it and the light remained on... I fiddled with the switch for awhile but got nowhere... however... what I did notice was that the light remains on constantly, but when I use the parking brake it gets a tad brighter, then when I release the brake it dims but stays on... this car confuses me sometimes...
 

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That is pretty normal, because you are adding an additional ground to turn the light on.
I am pretty rusty on '85 Deville, but it seems to me that it could be the result of an ABS code.
If I remember I'll try to see if I can find an 85 manual today. This is an FWD car we are talking about right? (sorry I work on lots of cars, hard to remember 20 years worth).
 

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1991 Cadillac Brougham D'Elegance 5.7 Litre, 1994 DeVille
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I don't think you could even get ABS brakes on those DeVilles. Is there another light for brake problems or does it use the same light? Maybe that's why it's on.
 

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Yeah, I don't see any ABS stuff on there, sorry about that.

It looks like there is an additional switch according to the shop manual.
The things that can turn the brake light on normally are, the ignition switch (for the bulb check), the proportioning valve, if there is a system imbalance, the park brake switch, and a "low brake vacuum switch".
It is likely tied into the booster somehow and it senses low vacuum to warn you if there is a problem with the booster.
Take a look around, see if you see anything electrical tied into the vacuum booster and unplug it, see if the light goes out.
Otherwise you are probably looking at a short in the wire that goes from the lamp to all those switches. That could be anywhere.

HTH.
Sorry I took so long.
 

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Discussion Starter · #10 ·
Thanks for all the help... Today ill poke around to see if anything is disconnnected... as far as ABS the car did not come with it... and if there was low vacuum to the booster wouldnt that cause drivability problems? and I also thought that there was a seperate light on the dash to warn you of any brake system problems... hmmm... ill look into it some more...
 

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No, the red brake light is hooked to all those things I named, if it comes on you just have to figure out which one is messed up.

The sensor for the booster could be bad making the light come on even if there isn't actually a problem with the booster.
You need to find each switch and disconnect each one until the light goes out, then try to find out why that switch is activaing. It could be a bad whatever switch or an actual problem with that component.
You won't find anything disconnected causing the light to come on, just something that's plugged in that is either malfunctioning or telling you that something is actually wrong with the brake system.
 

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Discussion Starter · #12 ·
Thanks for the help ewill3rd, I did as you said... the sensor that goes into the booster had two of the wires frayed and were making contact with each other. I used some electrical tape to cover them up and the light finally went away... now im off to fix the other countless problems with my car... :yawn:
 
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