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03 Cavalier, abs, trac off and brake lights on

09-06-2009, 10:06 AM
Been messing with this for about 3 weeks now. Whenever car is started, the Brake, ABS, and Trac Off lights come on after about 5 seconds. When this problem first started, it only did it in the mornings, run car for about 5-10 minutes, turn it off then back on and all was well. Now its persistent and will not shut off.

Most of what I read on here and other sights the light combo is abs/trac off/service engine lights. My service engine light does not come on, instead the brake light does.

I pulled codes off of it and out came alot of data link error codes throughout all the computers, and the one for the ABS was U1300, data link low. There were no wheel speed sensor codes (which appears to be a common problem) so we can eliminate that issue. Just had the alternator tested couple days ago, so we can also eliminate that.

Can anyone point me in the right direction to head with this thing? I am assuming it is some sort of electrical issue somewhere, but I looked at every single plug under the hood, wiggled, unplugged, inspected, replugged, etc...

09-06-2009, 11:38 AM
Try pulling codes with a different scan tool. Sounds like the one you are using is having some compatibility issues. Once you have the right info this should be a breeze to repair!

09-06-2009, 11:47 AM
The scan tool I used is very decent one. Name of it escapes me, but it does all the tests and stuff and could control some of the car's functions (I played with it for a while).

I did read one post buried in here where someone did say the had the same 3 lights, and it turned out it was his ABS module he had to replace, and I would start to lean that way, if the problem started off constantly, but since it was intermittent and then progressed to constant, leads me to believe it was some sort of wiring issue.

But I might go ahead and do some calling around see if anyone else with a scan tool that can do it for hopefully free. I know advance/autozone's scanners can't pull up these kinds of codes.

Little update on the problem. Haven't had a chance to get it rescanned, but found out something that makes this problem even more weird

Was sitting in car while wife did stuff. Turned a/c on (usually don't turn it on) and the Brake and ABS lights went off, and the service engine light came on. Trac Off stayed on.

I turned the a/c off, abs and brake came back on, and trac off and service engine light stayed on.

I did this like 10 times. So did a little prodding. I turned a/c on, lights went off, i then pulled the cooling fan fuse from under the hood, lights came back on. I plugged cooling fan fuse back in, fan started back up, lights went off.

Not exactly sure what to make of this... since the abs could really care less what the a/c is doing I would imagine.

10-06-2009, 04:01 PM
just to give an update incase anyone else runs into this problem. I finally figured it out today. Turns out had nothing to do with any of the computers, or the wiring for the computers. It was traced down to a chime module I bought at walmart about a year ago. This module allowed you to keep the dinging for the headlights and such, without the stock radio (which used to do it). I unplugged it and lights went away. so needless to say, I removed it from the radio wiring harness, redid the wiring for it. And viola, no more lights. Only downside is wife has to be extra careful not to leave the headlights on now.

I'm assuming something inside the module started to go bad, and was possibly sending voltage back through the harness, messing everything up.

10-06-2009, 11:01 PM
Nice job figuring it out!

Thanks for posting the fix!!!

10-24-2009, 09:31 PM
Hey, way to go.
My sunfire started doing the same thing about a month ago. Been pulling my hair out tracing grounds (try getting to the one under the battery tray). I tried to use a Actron ABS scanner to pull codes but it wouldn't link, BUT would turn the ABS/Brake lights on and off when plugging/unplugging it.
I'm going to pull that chime module out ASAP and see if it solves my problem.

On a side note i wasn't impressed with the Actron ABS scan tool, as i said wouldn't link to the Sunfire, interfered with OEM security system in my 04 Dakota causing a no start and showed a wheel sensor failure on my wifes 99 Grand Cherokee which does not have ABS light on as it should with sensor failure.

11-27-2009, 09:08 AM
It was traced down to a chime module I bought at walmart about a year ago.

Thanks, my daughter's car had this same issue. Your post saved me many hours of troubleshooting. :thumbsup:

11-27-2009, 09:24 AM
Wonder why we all started having this issue about the same time?
Any way it goes i pulled that stupid box and now no problem.
Thanks again for all solution.

11-28-2009, 02:34 PM
Wonder why we all started having this issue about the same time?

Maybe we're just the lucky ones that made it here. I can only imagine how many others are out there thinking the solution falls to bad PCMs, ABS modules, instrument cluster microprocessors, etc.

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