Faulty ABS

[Bernard Littau]

Hi Mike,

The sensors sound like they are fine.  I think you should swap in a known
good ABS relay -- I suspect that relay does more than just power up the
hydraulic modulator.  After that I would swap in a known good ABS
Controller.  If both of these prove fruitless, then I would suspect and
chase after funky connections.

I can't remember what the '89 has as far as diff and ABS control.  Does your
car have the ABS off switch or manual diff locks?  Activating the diff locks
will turn on the ABS light.  Make sure a diff lock is not on.

Bernard

>
> Thanks, Bernard, but I have checked the resistences to the wheel sensors
> and they are all about 1K4 ohms which is in spec (according to the Bentley
> manual). I know that the ABS relay is working because I have tested the
> voltage at the changeover relay under the lid of the actuator unit in the
> engine bay. I'm glad to hear that the control units are fairly robust, so
> I'll have another look for faulty wiring. Perhaps I have an intermittent
> connection which works when I pull the connector to get my multimeter to
> it
> and fails when I put the connector back on the control unit.
>
> Cheers, Mike.
> '89 200qta.
>
>
>
>
>                     "Bernard Littau"
>                     <bernardl at acumenassoc       To:     "'paul fernandes'"
> <paulfern2000 at yahoo.com>, <Mike_Buckham at ptk.pioneer.co.uk>
>                     iates.com>                  cc:
> <quattro at audifans.com>
>                                                 Subject:     RE: Faulty
> ABS
>                     02/09/2003 06:00
>
>
>
>
>
>
> You are correct in that the ABS light being illuminated from ignition on
> means that it is not a dirty wheel sensor or a wheel sensor out of
> adjustment.  If it were either of these, the ABS light would come on
> several
> seconds after the car starts to move.
>
> It could still be an open or a short to one of the wheel sensors, as far
> as
> I recollect from the ABS system when I did battle with it several years
> ago.
>
> The Main ABS control electronics under the rear seat are fairly robust and
> not likely to have failed.  The ABS relay, under the dash on the left side
> of the USA Steering wheel, seems most likely as the culprit to an ABS
> light
> on all the time problem.  I wound up replacing mine, after testing with a
> known good one from another car.  The ABS relay is reddish, with a fuse
> stuck in the top.
>
> Best,
>
> Bernard Littau
> Woodinville, WA
> '88 5ktq
>
>
>
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