ok, I did my homework and have searched for weeks for this info,
however
I was not completely successful. I also bought Chilton's repair
manual, the
info there is missleading.

Anyway, the temperature gauge works and shows the correct temperature.
The
relay that turns on the fan works. Actually I have to ground one of
the yellow
wires in the relay so that the fan will turn on. So for now it's a
manual process. The book says that there is a fan switch temperature
sensor on the radiator, but I have not been able to locate it.

Does anyone know where that sensor is? Another mechanic told me that
there is none, that it is the gauge temperature sender sensor near the
thermostat that causes the fan to turn on, and that it could be the
one of the computer modules.

Please help me.