"Terry Pinnell" > wrote in message
...
>I have a 1996 N-reg BMW 328SE Auto. Its ABS light is coming on and staying
> on while driving. However, using the CHECK button on the computer panel
> displays 'Check Controls OK'.
>
> I haven't been able so far to test it out on a suitable surface, but
> should I assume it's broken? If so, is a repair likely to be within the
> capabilities my local garage (which regularly services the car), or am I
> going to have to take it to an expensive BMW dealer please?
>

The ABS light being on means the ABS will not work -- your tires will lock
if you use the brakes in a panic, or on ice even if not in a panic.

ABS looks for a tire to stop turning as you apply the brakes. It it finds
one then the brakeing pressure is removed from that wheel for a moment and
then is reapplied. The result is that the wheel is allowed to turn so you
retain directional control over that wheel. The light being on means the
system is disabled and the tire will lock and remain so until you release
the brakes.

This is not a fatal condition -- we drove around for decades without ABS
systems. Indeed, in the early days of ABS, lots of people wanted information
on how to disable them.

In any case, you have a failed speed sensor in one or more of the wheels.
Odds favor just one failed sensor, but there are four of them and you have
no clue which one. You need a diagnostic device that connects to the Data
Link Connector (the round one by the right-side shock tower in the engine
bay) to read which one has failed. Replacing a speed sensor is not a
difficult task, and one that most people should be capable of undertaking at
home.