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Old 02-26-2006, 01:58 AM   #1
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Default Possible short in the brake switch

Is there a known problem with the brake switches on these cars that might cause a short when the brakes are applied or the turn signals are engaged? When I step on the brakes, not only does my voltage often drop dangerously low (as in the headlights almost died on me the other night driving home) but there seems to be feedback into the rest of the electrical system because my headlights flicker for a second along with all interior lights and the speedometer needle jumps right as I step on the brake pedal. The battery has been tested and checks out fine and the alternator charges just fine any other time except when the brakes are applied. I'm just curious if there is a common short that can cause this. Thanks!
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Old 02-26-2006, 02:32 AM   #2
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I had similar, but not as severe symptoms before. One by one, electrical component upgrades have eliminated it. But the single one thing that helped the most was the "big three". Bigger gauge wire battery to alternator, battery to ground, and engine block ground.
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Old 02-26-2006, 02:55 AM   #3
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Where is the engine block ground located? I figured there was one somewhere but I haven't been able to locate it.
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Old 02-26-2006, 08:32 AM   #4
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Follow the negative cable off the battery. It should go right there behind the battery.
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Old 02-26-2006, 02:13 PM   #5
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I think you have a problem in your brake/tail light ckt. What'* going on with the brake lights when this anomaly occurs? Locate the fuse for the brake/tail light ckts. and remove, then try the brakes to check for any change in conditions. Try to localize or isolate the problem to a specific ckt. You're dropping way too much voltage when applying brakes. Voltage to ground?
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Old 02-26-2006, 02:48 PM   #6
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Quote:
Originally Posted by markwb
I think you have a problem in your brake/tail light ckt. What'* going on with the brake lights when this anomaly occurs? Locate the fuse for the brake/tail light ckts. and remove, then try the brakes to check for any change in conditions. Try to localize or isolate the problem to a specific ckt. You're dropping way too much voltage when applying brakes. Voltage to ground?
That is what I'm suspecting. Part of the problem with diagnosing this is that it is transient, so I never know when to check it, or I know when to check it but I'm on the road somewhere. Sometimes, the car almost dies at stop lights because I'm holding the brakes and I can watch the voltage drop, my lights start to dim, and the car starts to misfire. I shift into park and release the brakes, and everything goes back to normal. Other times, there is no problem at all, except a brief headlight flicker when I initially hit the pedal. The longer the car has been run the more likely it is to have this problem. So I guess I'm suspecting a short in the brake circuit combined with an old and less than perfect alternator.

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Follow the negative cable off the battery. It should go right there behind the battery.
That would be the battery to ground cable and I have located that thing (It'* TINY, but there is no corrosion or looseness there), but is there another one that grounds to the engine block under all that plastic underbody cladding in the front?
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