5kcstq ABS Problem

[Larry Mittell <lmittel@ibm.net>]

OK list, I've got a new problem with my 87 5kcstq. The ABS lamp illuminates at
random intervals of no more than, say, 3 minutes. I can't correlate the
phenomenon with anything, except it doesn't occur when the car is at rest. ABS
function seems to be normal when the lamp is extinguished; although, come to
think of it, I don't know that it's abnormal when the lamp is illuminated.
Resetting by cycling the ABS switch puts things right until the next
occurrence. Reference to the Bentley suggests this can't be troubleshot without
what looks like an elaborate factory test box. A visit to the homepage suggests
that there's not currently a reasonable way to search the archives. I'm flat
out of resources unless some of you kind folks have BTDT and are willing to
share your experiences. 

The only thing I can add is that ABS function was absolutely normal prior to
the car being parked for two weeks. During those two weeks a trickle charger
was connected to the engine compartment battery post, something I've done
routinely in the past.  Since the charger puts out 100 or 200 milliamps and
automatically stops when full charge is reached, this would appear to be a red
herring. Or is it? Since experiencing the problem, I had my mechanic re-gap the
wheel speed sensors with the correct Audi plastic caps. Any BTDTs will be much
appreciated.

Thanks,
Larry Mittell