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I had my 2002 GMC Envoy out today after about three inches of fresh snow. Everything was fine till i went to start it later on. The parking brake light ABS light and service brake system light all came on after i started it. Any ideas what may be causing it. The fluid level is good and everything has been working fine till now. Any suggestions on a easy diagnose?:confused:
 

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everything seems to work fine. I took it for a drive and all the lights went off. The abs and brakes seem to work fine. Clueless???
 

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2005 chevy trailblazer_ls
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maybe from it being so cold up there (dnt mean to stereotype but i mean, its canada) the fluids could have been cold restrictin the flow to the sensors...hense why you started to drive, they warmed/loosened up returnin the flow to the sensors bak to normal when the lights went off? idkk i goin out on a limb here but its plausible :bonk:
 

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could be possible its about twenty five degrees below zero celcius. Not being able to convert i dont know what that is in farenheit.:bonk:
 

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2003 chevy trailblazer_ls
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everything seems to work fine. I took it for a drive and all the lights went off. The abs and brakes seem to work fine. Clueless???
Glad to hear that it fixed itself. I've had the ABS light come on a couple of times in the winter when I spun the wheels going up my driveway and it has always "fixed" itself.
 

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same thing

along those same lines, i have a 2002 where the abs light, brake light, service 4wd light, and the blower motor does not work. I have learned there is a TSB 01016 out for this problem. does anybody have any insight or the service bulletin on this. thanks :confused:
 

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that sounds more like it. i went through the fuse boxes, and was not getting any power to the fuse for the fan which is fed from the ignition which has also been feeling weird when turning or removing the key. i'll check it out. thanks :undecided
 

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2004 chevy trailblazer_lt
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I would say, your problems could be one of the big three associated with ABS codes:
- the battery is faulty. (Suspect this if your battery is five years old or older.)
- the ignition switch is faulty. (Very common with these vehicles, and can cause ALL kinds of weird symptoms.)
- if the ABS code is read, and it reads a loss of voltage or a loss of communication to the electronic brake control module (EBCM), then you need to clean up the ground wire to the ECBM at the frame just below the driver's door.

My money is on the latter. If you can get your ABS code read, (most OBDII code readers can't read ABS codes, but a lot of shops have ABS readers) and it shows C0265, C0201 or U1041, then it may not be a bad ECBM; it may be just a bad ground.

It is such a simple fix that it may be worth doing anyway, even if you didn't get your ABS code read. Find the frame rail under the driver's side and follow it forward under the driver's door. Just as it comes to a short side rail, you will see a ground wire bolted to the frame on the side rail. It is easy to see and there are no other wires bolted to the frame anywhere near it. It has a single thick 12-ga. wire, ending in a ring connector and tab. The tab goes into a tiny slot below the bolt, and there is a bolt through the ring connector holding it in place.

When you look at it, you will see right away why this spot is vulnerable to corrosion under the wire ring connector. Simply unbolt the wire, use a wire brush attachment on a drill to thoroughly clean under the connector on the frame, both sides of the ring connector itself and the threads and under the head of the bolt. Bolt it back in, and as soon as you get a chance, spray it with a small shot of rubber undercoating to seal up any bare spots still exposed.

This one little ground on 02 to 07 vehicles seems to cause problems in winter climate conditions when the temp plunges. Mine always seems to happen a day or two after I wash the truck in the winter, and it came on about 4 times last winter and once this winter. I now cleaned up the contact area and no more ABS and brake warning lights.

If this is not warranty work and is coming out of your own pocket, I would suggest spending a few dollars just to get the ABS code read. If it comes up C0265, U1041 or the likeliest one C0201, then bingo, you know what it is.
 

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Discussion Starter #14
After taking mine in to the dealer for another unrelated issue it turns out it was the EBCM that needed to be replaced. Thankfully warranty is going to cover it. They say around a thousand for it but that is the dealer price. Wholesale probably $9.99:crackup:
 
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