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Discussion Starter #1
My 92 Caprice wagon suddenly has no brake lights (except third brake light) Runnig lights and turn signals work fine, fuses look good and tried replacing bulbs-nothing made a difference.

Is this possibly the switch under the dash or am I going to have to start tracing for a short? It really puzzles me as to why the third light still works while the others don't.

Any help would be greatly appreciated!!
 

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Bret have you checked to see if you are getting power the bulbs? If the 3rd brake light works that would elimate the brake light switch. I bet that you have a bad connection someplace, do you have a trailer hich setup on the wagon? Check there & see if a power wire has been broken. Let us know what you find
 

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Discussion Starter #3
Johnny,
I don't have a hitch. The bulbs are getting power for the turn singals/running lights, but the second element in all four that is for the brake light are not lighting up. I didn't know if possibly the third brake light switch was on a separate circuit as a backup or something? I hate to just start throwing parts at it, but I also really hate tracing electrical problems.

Any suggestions on what/where else to look?
 

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Originally posted by bretcopsey:
Johnny,
The bulbs are getting power for the turn singals/running lights, but the second element in all four that is for the brake light are not lighting up.
Johnny's question about the lamps getting power will require a volt meter or test lamp to test. It takes both power and ground to light the lamps. So having them "not light up", isn't an absolute result - it's the symtom, not the problem.
 

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Don't the turn signals and the brake lights use the same filments and same feed wires? Also when I am following a car, sometimes I notice the brake lights and third light don't come on at exactly the same time. I would be sure the brake light switch doesn't have two seperate circuits and then check the feed from the stop light switch to the turn light switch. If that all checks out, suspect the turn signal switch.
 

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On my 96 Jimmy the High mounted stop lamp is directly powered from the load side of the brake switch, some cars and GM pickups have a relay that operates the high brake lamp. I think this relay is what causes that slight difference between when the brake lamps come on and when the high brake lamp comes on.

The normal brake lamps are powered from a parallel circuit that goes through the emergency flasher switch AND the blinker circuit. There is a contact in the emergency flasher switch that is normally closed that allows power from the brake switch to pass through it to the two rear blinker switch contacts in the blinker switch. As long as the blinker is in the center position, power passes straight through these two contacts (left and right)in the blinker switch and on to the brake light filaments.

There is a separate feed from the fuse panel for the blinker circuit that also feeds the blinker switch, that also comes thru the emergency flasher switch. The blinker circuit to the rear lamps are fed thru a different set of contacts in the blinker switch (mine has seven sets-front left and right, rear left and right, two brake lamp feedthrus, and one spare). The two sets of contacts for the brake light filaments join back together after the blinker switch, so if you rear blinkers are working, but the brakes aren't it looks like the problem is in the emergency flacher switch.

If you have the same type of setup maybe the contact in the emergency flasher that feeds thru to the brake lights is stuck open. Did you use it recently? Try to cycle it on and off a few times to see if you can free it up.
 

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I had the same problem with my son`s 88 monte carloss. It had a bad connection at the bottom of the steering column. You should be able to trace the wire from the brake light switch to the column. If my memory serves me right it was a white wire. If you can get a wiring diaghram you can check the power coming out of the column connector. It was the connector that connects the column to the under dash wiring harness. His car did the same. Third brake light would lite but no brake lights.
 

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Discussion Starter #9
I think it's fixed!!

I just wanted to follow up with what ultimately happened. The switch was indeed the culprit. I had been trying everything I could think of to no avail. This morning someone came up to my desk and told me my third brake light was on! I went out to the parking lot to unstick the switch and it turned off. Then this evening my wiife followed me home and told me that every time I hit the brakes all the lights were coming on, but sometimes the tail lights would then go out. I decided that a switch didn't cost that much really, so I took the old one out. When I opened up the switch, it became clear to me how it was possible for the third light to still work while the other two didn't.


Anyway, I just thought I would post back the happy ending for future reference. Thanks guys!
 
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