Re: ABS sensor problem *******I need Help *******

["Fred Munro" <munrof@isys.ca>]

Howard;

    Having the ABS pulse just as the car comes to a stop is not uncommon -
mine occaisionally pulses once or twice just as the car stops if I am
braking hard.
    The clearance between the ABS sensor and the rotor inductor is crucial
for good operation. AFAIK, the white plastic cap you mention is actually a
sacrificial clearance setting device. The cap is put over the ABS sensor and
the assembly is slid forward until the plastic cap touches the bars on the
rotor inductor. This sets the proper clearance for the sensor.
    If the inductor bars rust or are damaged, the sensor may not be getting
a good signal.

HTH

Fred Munro
'91 200q  258k km
-----Original Message-----
From: AQUATTRO4U@aol.com <AQUATTRO4U@aol.com>
To: Quattro@coimbra.ans.net <Quattro@coimbra.ans.net>
Date: Wednesday, September 16, 1998 6:25 PM
Subject: ABS sensor problem *******I need Help *******


>Hello Fellow listers,
>
>I am experiencing an ABS problem in my '88 5000TQ. When I come to a stop
say
>around 0 MPH my ABS pump turns on and I feel a vibration in the pedal. It
>happens about 8 of 10 times I stop.
>
>This problem started when I took it to a shop to have my right rear hub
>replaced as one of my lug holes was messed up. When their mechanic put it
all
>back he messed with the ABS sensor and adjusted it too close. I know this
>because we heard a metal to metal sound and then a click, click sound when
we
>pushed the car off the lift. My girlfriend asked him did you forget to put
>something on the car or are there any parts leftover? He said I must have
>adjusted the sensor too close. He adjusted the sensor a bunch of times
until
>my car would drive without the ABS off light turning on. I started for home
>and got on the freeway and everything was OK till I hit 75mph then the
light
>would come on. I found if I dropped my speed turned the ABS back on, the
light
>would stay off until I got back up to 75 MPH. This shop I had used for the
hub
>was way out of town and because they screwed things up I didn't feel
confident
>in bringing my car back for them to fix it. So I brought the car to my
local
>mechanic the guy I usually use. Of course he was bummed I went somewhere
else
>and now he has to try and solve a problem he didn't create but he tried his
>best to help me. The right rear ABS sensor was all bent. The plastic cap
was
>missing and the slotted tip was all bent back. So I located a used one at
>German Auto Salvage went there picked it up and brought it back to my
>mechanic. It turns out the used one I bought was bad as we checked it with
an
>ohm meter and it read 0. So I called them up they had another one so I went
>and got that one. I brought that one to my mechanic it was fine and he put
it
>in. He used his Bosch computer and tried to set my sensors the best he
could.
>He spent over 3 hours diagnosing the problem. The mechanic took it out on
the
>freeway did 100mph and said the sensor didn't come on. So I picked up my
car.
>The ABS pump and vibration is still happening when coming to a stop at
around
>0 MPH. Also when I took the car up to a 100MPH the sensor did not come on
>until I changed lanes. This happened again at around 80 MPH when I changed
>lanes and went over the bumps. I then went 100 and 80 tried changing lanes
and
>nothing happened seems like it happens sometimes. Still when I come to a
stop
>the ABS pump turns on and I feel vibration in the pedal. I have been
dealing
>with this for 1 week and a half now and I think I'm getting an ulcer over
>this. Won't someone who has previous experience please shed some light on
this
>subject before I really go nuts. I know I can simply turn off my ABS and
>everything is fine but I want to fix this problem. I would like to have the
>ABS working as it might save someone's life someday. Maybe even mine.
>
>Advice to others please don't let anyone ever touch your ABS sensor as it
will
>become your worst nightmare if you do.
>
>So I'm now asking for some help:
>
>Does anyone know what could be causing this problem?
>
>I bought a new cap for the used sensor we already put in.
>Do you think the other 3 sensors need a new $2 piece of plastic?
>As I have already ordered them thinking the plastic cap might somehow be my
>miracle cure.
>
>Does anyone know what number the Bosch computer that you hook up to the ABS
>computer should read when the wheels are spun?
>
>Thank you in advance for your help.
>
> Howard Dinits
> '88 5000 TQ
> AQUATTRO4U@aol.com