5kQ ABS: The light is on ... nobody home?

[steveb@falcon.kla.com (Steven Buchholz)]

Funny thing we should start talking about ABS ...

Well, the ABS OFF light on the '88 5kCSQW stays on all the time.  I 
tried locking and unlocking the diffs and pressing the ABS OFF switch.
When I do these things I can hear a relay clicking, but the light stays
on.  I haven't had a chance to dig into it yet, but I looked through 
Bentley, which said that the first thing to do was to check out a few 
fuses and relays.  It also sounds like one of the first tests is to 
see if the brake modulators work under hard stops even though the light 
is on.  Have any of my esteemed colleagues had to deal with a similar 
problem?  If so, what did you find as the source?  Bentley suggests 
using some big electronic monitoring tool that gets inserted in-line 
with the connector on the ECU ... does anyone know if this has any-
thing more than what I could get by probing wires with a DMM?

TIA ... as always!
Steve Buchholz
s_buchho@kla.com
San Jose, CA (USA)