ABS Not Working?

[Phil Payne]

> When I start the car in the morning the light is off and I can press the
> switch and make the light come on or off.  About 20 seconds after I start
> driving the light comes on by its self.  If I press the switch when driving
> the light will only flicker.
>
> So this seems to me to be a wheel sensor problem.  What is the wheel actually
> sensing? Do I need new break pads? can I replace a bad wheel sensor? How do I
> figure out which wheel?

The wheel sensor wires arrive at the controller connector in pairs of wires with the same base colour and no stripe.

If you spin the relevant wheel, you'll see a weak signal (in the millivolt range) across the pair of wires for that connector.

This procedure will find breaks in the wiring.  Otherwise, suspect any hub that's been taken apart recently, then start at the
front.