trac off / abs light and flashing low trac

I'm having trouble with my 99 Alero V6, I found this site and it seems I'm not the only one, however my problem sounds a little different from the ones described.

Problem:
While driving the low trac light comes on and starts flashing for several seconds. Following this both the low trac and abs lights come on and stay on until the engine is shut off and the car is restarted.

Any ideas what this means?
Does anyone know if the ABS system turns off when this happens or if it is still working?

From previous messages posted it seems people think the trac off light may represent a problem with the speed sensor. Is it necessary to replace? What does the speed sensor do?

Any help would be much appreciated.

Welcome to the forum. You're lights indicate that either A) you have a bad wheel bearing(s) / hub assemblies, or, more likely B) - you have a faulty wheel speed sensor(s). This is very common in N-bodies (all us newer aleros, grand ams, and malibus have problems with those sensors). It's most likely the sensor has gotten dirty, and it thinks that the wheels are moving at different speeds, when they're not. If cleaning the connections doesn't help, then you're only real other option would be to find out which one is bad, and replace the whole hub assembly (the connectors part of the unit).

Hi, I'm new too and not auto savy at all. I'm having the exact same problem as you will both the low trac, trac off and anti-lock lights coming on and not going off until the car is shut off. Sometime it's just the low trac and anti lock ones. 1 difference is that my wheels spin right before I start to go (tires are in fine condition), other than that it performs fine. It's odd because it started right after I had an oil change done so I'm wondering if they knocked something out of place. Any ideas anyone?

Hi, I'm new too and not auto savy at all. I'm having the exact same problem as you will both the low trac, trac off and anti-lock lights coming on and not going off until the car is shut off. Sometime it's just the low trac and anti lock ones. 1 difference is that my wheels spin right before I start to go (tires are in fine condition), other than that it performs fine. It's odd because it started right after I had an oil change done so I'm wondering if they knocked something out of place. Any ideas anyone?


I agree with the other suggestions provided. It's probably a wheel sensor or the wiring. The oil change was probably just a coincidence. If you have access to a digital multi/ohm meter you can measure the resistance of the wheel sensor and it should read in the following range. Just disconnect the electrical connector to the sensor and measure across the two terminals (hub side):

1530 - 1870 ohms

If out of this range the sensor is bad. You'll have to get a complete hub/bearing assembly.

bnaylor3400-i agree as well, this is a common prob, i just have been lucky and not had it. my alero is 128,080mi on it and its a 99 v-6. runs great. had nwe frunt shocks, springs put on. i some how broke a sprong on the pass. side.

bnaylor3400-i agree as well, this is a common prob, i just have been lucky and not had it. my alero is 128,080mi on it and its a 99 v-6. runs great. had nwe frunt shocks, springs put on. i some how broke a sprong on the pass. side.

Yeah, I agree it is a common poblem on the Alero and Grand Am. I still have the original hubs and sensors too.

I've seen and heard of other Alero owners with broken springs, especially on the '99 - '00 models.

Speaking of struts, what brand did you use? We wanted to put on aftermarket struts but the Monroe and Gabriel brands will not work on an Alero GL2 because it has the FE3 performance handling/suspension package which is the same as the Grand Am GT. If you want the same characteristics you have to use the OEM AC Delco struts which run $120 a piece. :dunno:

Monroe is what i used, but i also had a bearing bad on the pass as well. all together causted me a little penny. 950 bucks. i did not have the time to do it myself. But even if i did it myself, i would need an alignment as well. i like the -0.02 camber. so it will toe in;to meet the road better.

My Abs light and low track light come on. Where is the sensor located to trouble shoot this issue. Their must be a wire somewhere on the wheel that reads the speed of the tire.

My Abs light and low track light come on. Where is the sensor located to trouble shoot this issue. Their must be a wire somewhere on the wheel that reads the speed of the tire.

The wheel sensor is located within the hub assembly. The electrical connector plug should be visible. Just follow the single wiring harness on any wheel that runs along the control arm. If the sensor is bad you'll need to replace the hub/bearing assembly.


BTW - The resistance of the sensor can be measured with a multimeter (ohms). 1530 - 1870 ohms

The wheel sensor is located within the hub assembly. The electrical connector plug should be visible. Just follow the single wiring harness on any wheel that runs along the control arm. If the sensor is bad you'll need to replace the hub/bearing assembly.


BTW - The resistance of the sensor can be measured with a multimeter (ohms). 1530 - 1870 ohms

How hard is it to replace the hub/bearing assembly. I looked in the Chiltons manual but I am still confused. The said that the whole assembly needs to be replaced and the sensor is located somewhere under the left fender well. I pulled the covers and I couldnt find anything that looked like the pictures. This car is killing me with all these issues. I'm thinking about buying Japanesse next-time. 47k mile and I had numerous issues.

How hard is it to replace the hub/bearing assembly. I looked in the Chiltons manual but I am still confused. The said that the whole assembly needs to be replaced and the sensor is located somewhere under the left fender well. I pulled the covers and I couldnt find anything that looked like the pictures. This car is killing me with all these issues. I'm thinking about buying Japanesse next-time. 47k mile and I had numerous issues.

There is one sensor located on each wheel as part of the hub. The Chiltons was probably referring to the ABS Modulator which is located under the left fender on the subframe towards the front of the car. The wiring from each sensor connects eventually to the ABS Modulator/Motor assembly.

To replace a hub, the respective wheel has to be removed along with disc brake rotor, caliper and mounting hardware. There is a big axle nut with holds the hub onto the drive axle spindle. If the hub doesn't cooperate or is very tight, a special tool called a hub puller will be needed. Not an easy job but it can be done DIY. You will also need a 0 - 200 ft lb torque wrench because the axle nut must be properly torqued to specifications during assembly.

There is one sensor located on each wheel as part of the hub. The Chiltons was probably referring to the ABS Modulator which is located under the left fender on the subframe towards the front of the car. The wiring from each sensor connects eventually to the ABS Modulator/Motor assembly.

To replace a hub, the respective wheel has to be removed along with disc brake rotor, caliper and mounting hardware. There is a big axle nut with holds the hub onto the drive axle spindle. If the hub doesn't cooperate or is very tight, a special tool called a hub puller will be needed. Not an easy job but it can be done DIY. You will also need a 0 - 200 ft lb torque wrench because the axle nut must be properly torqued to specifications during assembly.

One last question : It is possible to check the ohm rating on each sensor without removing these parts or is that necessary? If so, is the sensor accessible by only removing the wheel? Thanks for the help...

One last question : It is possible to check the ohm rating on each sensor without removing these parts or is that necessary? If so, is the sensor accessible by only removing the wheel? Thanks for the help...

Yes after jacking up and removing the wheel, just undo the electrical connector at the hub. Then you can measure across the 2 pins for the resistance.

You are welcome and good luck!