RE: <E34> Erratic Speedometer: Wiring diagrams anywhere?

[Hendrik Pieterse <Hendrik@xxxxxxxxxx>]

Hi Ted

I have a '90 535i, with a problem very similar to yours. My speedo 
sometimes (even while standing still) jumps up to 130km/h, while the
RPMs
remain constant. It seem to happen more often while turning the ignition
to position 1
than during actual driving.
 
Have you had any luck sorting out your problem? Did you have to replace
the
Diff-sensor?

I am unable to locate any electrical wiring diagrams for my vehicle - is
there an electronic copy available anywhere? 

Any help appreciated

Hendrik
'90 M535i Ramming through the garage wall at a snail's pace

> 
> Date: Wed, 23 Sep 1998 21:42:56 -0400
> From: "Theodore W. Matthias" <twm@domain.elided>
> Subject: <E34> Erratic Speedometer: Vehicle Speed Sensor???
> 
> Recently, I have noticed erratic speedometer behavior in my 89 525ia.
> When the car crosses large expansion joints, the needle 
> suddenly, albeit
> momentarily, drops its reading though the vehicle speed and 
> RPMs remain
> the same. This is now beginning to happen without the aid of expansion
> joints.
> 
> This becomes a real problem when I use the cruise control.  
> Evidently, the
> drop in indicated speed is sensed by the cruise control 
> controller (!) and
> the unit accellerates then decellerates to compensate.  The 
> net effect is
> that I'm beginning to feel like a whiplash test dummy.
> 
> Since the tach remains unaffected when the speedometer exhibits this
> problem,
> I don't think it is the engine's RPM sensor.  From reading 
> the electrical
> diagrams, I am aware of a "vehicle speed sensor" located on the
> differential.
> 
> Could this be the problem?  Does anyone have experience with 
> one of these
> do-hickeys?  How do I test it?  How do I find it?
> 
> Thanks in advance...
> 
> Ted Matthias
> 

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