ABS/ Trac light

[Pyle]

My ABS and my trac control do not work. Both lights stay on all the time. What would cause this. I thought it could be an ABS sensor, but the ABS would still work, right? I know the parts for this are expensive, so I want to make sure I get the right one the first time. 99 Grand Prix GT

[DiscoStudd]

I'd put my money on it being a faulty wheel sensor. Both the ABS and Trac Control share the wheel sensors.

 

Unless you have a TECH II scanner, the only way you can retrieve ABS trouble codes is to take it to a dealer or brake "specialist" ...

[Pyle]

So, will a bad sensor cause the entire system to go out? I thought there was a way to check them other than using a code reader, multi-meter maybe? If so, exactly how do I use that? I think I actually have one, one of those tools that just sits there because I don't know how to use it, lol. Would I have to plug it into the sensor itself, or the wire harness? I am assuming the sensor is on the main wheel hub assembly?

[DiscoStudd]

The sensor is on the hub, and will cause both the ABS and Trac Control systems to go out.

 

I'm fairly certain that your garden variety code reader won't be able to retreive ABS codes. The TechII is a "GM dealership-only" scanner (although I've seen them on eBay go for several thousand dollars) and will retreive the codes through the OBDII port...

[terryk2003]

i have to agree with disco...wheel hub/abs sensor...

[DiscoStudd]

My wife's sister and her hubbie have a 2000 Impala that they just had the wheel sensor and hub replaced on. It cost them (supposedly) $400 to have the dealer replace both the sensor and hub. Their original problem? ABS and Trac Light were constantly lit...

[nebojsa_o]

I'm having a similar problem, and I'm pretty sure it's a wheel sensor, and so far I "narrowed" it down to one of the rear 2. So if it cost $400 for the dealer to fix it, how much would that be for a DIY guy? Can you replace just the sensor, or is it fixable sometimes? Or do you need the whole hub?

[94CutlassSLCoupe]

Wheel speed sensors are removable from some designs, and not removable from others. I've never looked very closely on a W-body to see which design they are, although i'm almost postive the front ones can be seperate from the bearing.

 

I would just J/Y the parts for a Gen I since the bearings and WSS seem to barely ever go bad.

 

Once the sensor has a fault, you have to replace it! It is possible that it has a problem with rust growth in some designs that increases the air gap of the sensor versus its relutor ring, but I have not heard of this being a problem on Gen I cars at least, even though this is a very common problem on almost any 4wd GM vehicle.

[coopinwpg]

I've got a 99' Intrigue GX and have been plagued by a similar problem to what you've described with your ABS and Traction Control system.

 

First my problem was diagnosed as a front wheel hub sensor that had gone faulty causing the ABS system to throw codes constantly. There was actually a "clanging" at the troubled wheel every time it hit a bump. Replacement of the hub and sensor cost me $600 CDN.

 

Every once in a while the system would act up by giving me "Low Trac" warnings in a seemingly random fashion. I noticed it happened more frequently during wet or cold weather.

 

This last month the problem had been occuring daily. so I took my car in and was told that the right front sensor was loose. After they made sure it was in tight they drove it and could not get it to throw a code. But on my way home it tripped again and so I drove it back and had them scan it again. The code was for the right wheel sensor again(Same one they had replaced before). It turns out the wire harness in the engine compartment was to blame. Apparently it picks up the movement of the accessory belt or timing chain causing it to get a mixed sensor reading resulting in the ABS and Traction Control faulting. By keeping the wire harness as far away as possible form the moving parts the problem has almost dissapeard. It still trips once in a while, but it's only happening while making full lock turns during very slow speeds. I may just replace the entire harness and see if that cures it for good.

 

Hope this info helps.

[DiscoStudd]

^^^ That's some good info!

[nebojsa_o]

My problem was the wire that goes to the sensor is isolated with some tape, looks like electricians tape or something like it, I coldn't tell it was rotten to hell. Well mine would always show up more often during and after rain, so when I was putting my new wheels on the car, I checked those wires, and the rear left wire had a bunch of water stuck inside the tape, so when I hit bumps and stuff, the water would drip down the wire, and the code would pop up. So I took off all that tape, cleaned the wires off, dried them off, and put new tape around. So far so good, no ABS light since then, and we did have rain. I was gonna post my solution, but didn't think I should start yet another thread just to do that, and I didn't see this one in a while. Maybe this will also help someone, but I was honestly expecting the problem to be more serious, not just a wet wire, lol.

[coopinwpg]

I'll have to check on the wires since my problem has not gone away. Thanks for sharing your solution.