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Hey everyone, I haven't been around in a while and I've missed all the great caddy talk around here, good to be back!

Anyway, my question pertains to my '85 Seville. Most of the time on start-up the brake light is on. If i let it sit and idle it eventually goes out after a couple minutes. I have brake pressure and haven't had any brake failure. I never see any brake fluid on the ground under the car either. Pumping the brakes doesn't seem to make the light go out. The light also comes on when driving, then after a couple minutes it will go back out. The brakes seem consistent and haven't been behaving any differently than when the light didn't come on. Any suggestions as to what could be causing this? Possible air in the lines or anything like that? I have the car listed for sale and don't want to show it with the brake light issue. Thanks!
 

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2008 SRX
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403 Posts
Bad vacuum sensor in the booster comes to mind. If a new one was available it wouldn't fix it. For some reason we used to see these act up and new sensors didn't help - maybe because the lower vacuum at the mile-high altitude.Check your vacuum supply and test the check valve. Test for manifold vac into the vac pump and higher vac going to the booster.
 

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85 Eldo Biarritz
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808 Posts
Yeah - probably the vacuum sensor. The vacuum sensor is on the booster can. See if by disconnecting it the brake light goes away. If it does then you found the culprit. If not, there is another problem. If that isn't it, disconnect the pressure switch on the master cylinder. Again if the light goes out - that one lights it up. The third posibility is the parking brake switch. Again - disconnect it to test it. I think that is it. If the light stays on with all 3 disconnected then you have a short to ground somewhere.

Peteski
 
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