"Anti-Lock Brake" light AND “TRAC OFF” light coming on

About 5wk ago I took my car to the mechanic due to my “Anti-Lock Brake” light AND my “TRAC OFF” light coming on. In addition to the lights, when I applied the brake, the pedal would move or pulse a little, and there was a moaning sound. The mechanic checked it out and ended up replacing my right, front “wheel hub assembly.” This fixed the problem. However, after 2 or 3 weeks, the warning lights began appearing again, and have continued to do so for the last couple weeks (although they appear only during SOME of my drives). YET, NOW THERE IS NO BRAKE SYMPTOMS (pulsing or moaning) like I had prior to taking the car to the mechanic. (In fact, back when I experienced the brake pulsing & moaning, those symptoms occurred for a couple of weeks PRIOR to the warning lights ever appearing.) Any ideas?
I have a 2004 Buick Century sedan, with automatic transmission (4speed) w/overdrive, V-6 engine 3.1 L.

The problem might be coming from the left front wheel hub assembly.

The hub assembly includes the wheel speed sensor/tone ring. If the bearing becomes worn and causes the wheel speed sensor to become misaligned with the tone ring it’ll cause the ABS light to come on. And if the ABS light comes on, the TRAC system light automatically comes on because it’s not going to function if there’s a problem with ABS.

So the bearing in the left front hub assembly could be worn where it causes the wheel speed sensor to become misaligned with the tone ring, but not worn enough to make noise or cause other problems.


Thanks! Any more opinions out there?


Have you read out the fault codes?

Could be something as simple as a bad stop lamp switch