How do you check ABS Sensors?

[Bob Rossato]

I got readings of around 300 mV on the rears and about 200-250 mV on the
fronts on the AC setting.  That was at the fastest I could spin the wheel by
hand.  On the DC setting best I could get was around a 9 mV spike.  So it
sounds like they are all fairly consistent.  What else is left?  Just the
ABS controller, right?  If that's the problem I'm sure he'll live without
ABS, rather than replace that.  Any thoughts?

Bob

> -----Original Message-----
> From: quattro-bounces at audifans.com
> [mailto:quattro-bounces at audifans.com]On Behalf Of Richard J Lebens
> Sent: Thursday, December 18, 2003 6:00 PM
> To: quattro at audifans.com
> Subject: Re: How do you check ABS Sensors?
>
>
> Never done it but it seems like the AC setting would work better
>
> --- Todd Young <auditodd at comcast.net> wrote:
> > I followed the cord to the nearest plug and pulled that apart. Then
> > stuck the leads from a volt meter into the plug that goes to the ABS
> > sensor. Have the wheel jacked up off the ground. Turn the volt meter
> > to
> > the lowest DC setting you have and turn the wheel. Mine registered
> > between 0.2 and 0.8 volts. It just "spikes" on a digital meter, it
> > doesn't read constant.
> >
> > Bob Rossato wrote:
> > > I'm doing some work on a friend's 1989 90.  One of the problems he
> > has is
> > > that when you first start the car the ABS system will activate for
> > the first
> > > couple of times you apply the brakes and then, apparently not happy
> > with
> > > everything, it will shut itself off.  Bad wheel sensor?  How do you
> > check
> > > them to find out which one it is?  Is it just a simple resistance
> > check?
> > >
> > > Thanks,
> > > Bob