Question2002 XG 350: The ABS and TCS lights keep coming on. They
extinguish if I turn off the engine for a bit. They seem to
come on if the car stands still and idles for a minute or
so. I believe this can be caused by muck building up in the
wheel sensors? If so, can they be cleaned, where are they
located and what do they look like?
AnswerIf the lamps are out at start-up but come back while the car is still, it's unlikely the the lamps are caused by a wheel speed sensor problem; such a problem would tend to be most apparent to the ABS/TCS module while the car is moving.
The sensors cannot be cleaned, but the tone wheels or rings (square-toothed wheels/rings) can collect debris or can crack, and either situation can cause the lamp to come on. On the front, there's a tone ring on the outer cv joint on each axle. To inspect them, you'll need to jack the front wheel off the ground so it can be turned, and then inspect the teeth as you turn the wheel. On the rear, there are wheels on the inside of the each hub, covered by a plastic cover. To inspect, pry the plastic cover off the back side of the knuckle/hub assembly and look at them. You may need to jack the rear of the vehicle off the ground or place it on ramps to gain enough access to do this.
Most likely, you'll need to take your car to a shop capable of ABS diagnosis and repair for them to read the codes and diagnose your problem. The dealer will be able to do this, but beyond that, I'm not sure which shops will have the tooling necessary to communicate with your ABS/TCS module. Note that this is outside the scope of most brake chain shops.
