No headlights when I press brakes.

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mike73

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Yes post a picture. In all the trucks I've owned (88 k2500, 92 c1500, 2000 silverado 1500, 1991 K2500 w/ hydroboost), I can't recall any wires coming out of a brake booster. Some of them had an ABS module below the master cylinder, but there were not any wires near the brake booster unless you're talking about the cruise servo above it or something like that. If a wire truly appears to be coming from behind the booster, I'd wonder if someone just used the brake hole in the firewall to run wires and something is getting pinched in a place that would be difficult to see.

Also, I haven't fully thought through the implications of this possibility but what if there is an open/faulty ground somewhere, maybe applying the brakes puts voltage on a ground side, causing things to turn off. This may not be consistent with it still occurring with the brake switch out, but we have to keep in mind that sometimes symptoms can be misunderstood if the problem isn't known
 

Turnerjcaleb411

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Still happened I’ll post pictures tomorrow an try to get a video of it. But it’s very very weird cause for example I hit a bump in the road an after that I use my brakes nothing shuts off, but other times I hit a bump in the road an use my brakes it shuts everything off. So that being said very well seems like a lose wire somewhere but still doesn’t explain when I disconnect brake switch it still does it I felt up around the shaft of the brake booster an no wires touching it. An always the wire around the brake booster are not color they are black/gray very small gauge wire.


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Eveready

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Still happened I’ll post pictures tomorrow an try to get a video of it. But it’s very very weird cause for example I hit a bump in the road an after that I use my brakes nothing shuts off, but other times I hit a bump in the road an use my brakes it shuts everything off. So that being said very well seems like a lose wire somewhere but still doesn’t explain when I disconnect brake switch it still does it I felt up around the shaft of the brake booster an no wires touching it. An always the wire around the brake booster are not color they are black/gray very small gauge wire.

Considering the intermittent quality of the problem I am still betting ground.
 

Turnerjcaleb411

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I flick on I turn on my light bar and I hit my brakes and my power still shots off so I’m guessing it’s the battery but I’m not sure what it could be


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evilunclegrimace

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I flick on I turn on my light bar and I hit my brakes and my power still shots off so I’m guessing it’s the battery but I’m not sure what it could be


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It is not your battery.
I’m bettering a ground also but there is no power running the the brakes at all so what could cause it? I’m stumped.


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Caleb,
You have already eliminated the brake switch by unplugging it. The switch it self has nothing to do with your problem. It sounds to me like you do not have much experience with automotive wiring so let us try to help you. First figure out if your truck has Vacuum brakes or Hydraboost brakes. Second post up the pics.

There are two things that these 3 systems(radio, dome light and head lights) have in common. Ground #302 and Splice #307. Everyone has said that it is most likely a ground. Find G302 and make sure that it is clean and tight.You will find G302 on the ALDL bracket. Check for continuity back to the battery with an Ohm meter to make sure that the ground circuit is complete. When you have done that get back to us with your findings.
 

Turnerjcaleb411

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It is not your battery.


Caleb,
You have already eliminated the brake switch by unplugging it. The switch it self has nothing to do with your problem. It sounds to me like you do not have much experience with automotive wiring so let us try to help you. First figure out if your truck has Vacuum brakes or Hydraboost brakes. Second post up the pics.

There are two things that these 3 systems(radio, dome light and head lights) have in common. Ground #302 and Splice #307. Everyone has said that it is most likely a ground. Find G302 and make sure that it is clean and tight.You will find G302 on the ALDL bracket. Check for continuity back to the battery with an Ohm meter to make sure that the ground circuit is complete. When you have done that get back to us with your findings.


Your completely right I have no knowledge of wiring and anything to do with wiring I’ll take picture of everything I have set up an try to give as much information I have to help. Yes I also have a few ground that aren’t connected but it’s been like that for month. But I’ll take picture tomorrow an I believe I have a vacuum brake system.


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Turnerjcaleb411

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I had installed a after market roof console out of a Yukon an had the map lights wired up to the dome an I unhooked them an fixed it somewhat


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