Aftermarket wheels and tyres may be the cause of this if they are not all the same size.

Once you have checked this, and the tyre inflation, then ABS sensors and wiring back to the computer will be the next thing as TKbenz suggests. There is only one sensor for the rear wheels, it is on front of the diff. If the diff is a non standard ratio then this could also cause the problem.

If the ABS computer thinks the wheels are not all rotating at the same speed, and it can't correct this by releasing the brakes, then it thinks there is a fault, shuts down and brings up the light.

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Mick J
'08 Chrysler 300CRD (MB OM 642 engine)
'95 E220 estate
'89 230TE (R.I.P.)