[s-cars] ABS Problems

[calvinlc at earthlink.net]

>which wires?

I don't have a bentley for my S4 so I will have to give you the pin names
for the wires on the 200 (Which is where I encountered this problem).  My
guess is that it is likely the same on the S4.

LF = pin 4 and 22
LR = pin 8 and 9
RF = pin 21 and 11
RR = pin 24 and 26

These are on the gigantic connector going into the control unit.  You need
to grab the voltage across the two wires with an o-scope.  Just do one wheel
at a time unless your the channels on your scope are independently grounded.

--Calvin


-----Original Message-----
From: Theodore Chen [mailto:tedebearp at yahoo.com]
Sent: Friday, August 11, 2006 10:03 AM
To: calvinlc at earthlink.net; Curtis Asplund; s-car-list at audifans.com
Subject: Re: [s-cars] ABS Problems


more details, please.  which wires?

i've also got an ABS light on.  then again, i just obtained a set of
ABS sensors from a 100/A6 so it may be easier to just swap them.  i
already have a suspect - the LF sensor shows damage from contact with
the reluctor wheel.

-t.

--- calvinlc at earthlink.net wrote:

> Also, I should be clear, the voltage I am talking about is the amplitude
of
> the sine wave created by the ABS sensor as the wheels turn.  You have to
be
> doing this at about 10+ mph to really see the difference easily.
Obviously
> tapping into the wires at the ABS computer under the rear seat is much
> easier than doing it at the actual sensor.
> --Calvin
>
>
> -----Original Message-----
> From: s-car-list-bounces at audifans.com
> [mailto:s-car-list-bounces at audifans.com]On Behalf Of
> calvinlc at earthlink.net
> Sent: Friday, August 11, 2006 9:30 AM
> To: Curtis Asplund; s-car-list at audifans.com
> Subject: Re: [s-cars] ABS Problems
>
>
> My ABS light problem started intermittently like yours and got worse over
> time as well.  Mine turned out to be the fact that the ABS sensors were
ever
> so slightly backed away from the wheel.  I gently tapped them back in with
a
> small hammer and had no more problems.  The way I diagnosed it was by
> putting an oscilliscope on the wires coming from the sensor back to the
ABS
> unit.  The voltage level of one or two of the sensors was substantially
> lower than the others.
>
> --Calvin
>
>
> -----Original Message-----
> From: s-car-list-bounces at audifans.com
> [mailto:s-car-list-bounces at audifans.com]On Behalf Of Curtis Asplund
> Sent: Thursday, August 10, 2006 4:32 PM
> To: s-car-list at audifans.com
> Subject: [s-cars] ABS Problems
>
>
> I've had the ABS light on for some time.  It has been intermittent, often
> off during the colder days of winter but now on 95% of the time.  I
thought
> it might have been dirty sensors themselves. My mechanic has diagnosed
this
> as the ABS pump Control Module (part# 4D0 642 111) with a part having
> superceeded that with the same number plus a "D" after it.
>
> Audi replacement cost is substantial.  I have lurked on this list for many
> years but can't think of this as ever having been something I have read as
> an issue.
>
> Are there any other things that could be checked?  Is this a part that
could
> be replaced with a used part or would that be throwing good money after
bad?
>
> Anyone out there have a car that you're parting out that would have one
> available?
>
> Any help would be appreciated.
>
> Curtis Asplund
> Redmond, WA
> 95.5 urs6 Avant  100k
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