Auto Check Diagnostics Question

[Dan Cordon]

Hey all,
FYI, I'm playing with a 1987 5kcstq.

I was hoping someone could help me with an Auto Check problem. I had the
coolant warning signal come up recently. It's supposed to indicate low
coolant or coolant too hot. I have neither of these conditions. It
happened yesterday and comes on consistently after starting the car up.

So far I've checked the coolant level sensor, and that checks out okay.
However I can't seem to locate the coolant temperature switch for the
Auto Check. I have the Bentley, but I can't seem to make sense of the
coolant sensor location. So far I've located two single wire sensors
(one on drivers side by front cylinder and one on the thermostat
housing), one two wire sensor on the thermostat housing, and the
thermotime switch. Any idea which it is, if any?

Any suggestions would be welcome! Thanks a ton--

--
Dan Cordon
Mechanical Engineer - Engine Research Facility
University of Idaho