'87-5000t ABS problem

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <34EAE5C6.614166F9@axxsys.com> Max writes:

> OK, bought this 5000 couple months ago and since getting it the ABS OFF
> light has been on.  I have taken readings on each of the four wheel
> sensors and they are fine, I've made sure that the shutdown switch is OK
> and can hear the relay clicking under the dash when pressing and
> depressing the switch.  Anyone have any other ideas before I give it to
> the dealer to figure it out?

I'm not sure when the change was made in the USA, but the later models have an 
accelerometer (mercury switch) under the rear seat, near the front edge.  It's 
a small black item with an arrow on top pointing in the direction of travel 
and two protective metal flanges sticking up either side of it.  It's quite 
easy to dislodge the connector ... 

I believe the switch is 'normally closed'.  Jumper across the connector pins 
and switch ABS off and on to see if it's defective.

ABS will also go off if it thinks the differential lock(s) are on.

-- 
 Phil Payne
 Committee Member, UK Audi [ur-]quattro Owners Club