'92 Corsica: How to revive my dead cooling fan?

[automan9482]

This is an update to my last post about some electrical anomalies with my '92 Corsica 3.1L cooling fan. I "solved" the issue in the last post with the chime and speedometer, by undoing the splice to the cooling fan relay and splicing it back how it was originally.
However, the cooling fan still will not work automatically, gauge will wander all the way up to Hot with no fan action, and I am stumped.
I have replaced the large firewall relay (cylinder shaped 2.8L old style), tested the fan (fine), tested the relay (fine), checked the dashboard fuses (seem fine), and replaced the coolant temperature sensor (smaller diameter sensor w/ 2 wires, also 2.8L old style).
I then read on an older post here where someone had the exact same problem and did the exact same fixes and still had the exact same problem, where the fan still would not kick on. I also see that the coolant temp. sensor is not the fix.
In that post, someone else recommends replacing the fan switch to solve the issue.
Where is the fan switch, please?? Chilton's manual is vague at best and doesn't seem to mention a fan switch, and I don't see it. I am so frustrated that I haven't been able to fix this seemingly simple problem, and I am out of ideas.
Can anyone help? Thanks in advance!

[danielsatur]

Did you replace the auxiliary fan control unit?
see www.partsgeek.com $16.35

[automan9482]

I did find the location of the fan switch on JustAnswer.com, but still nothing. I have replaced the large relay on the firewall, the coolant temp. sensor (gauge), and the coolant temp. sensor fan switch, which is straight down and back from the oil filler. Is that fan switch what you mean by auxiliary fan control? If I jump the fan switch, the fan will kick on by itself and stays on even after the jumper wire is removed. This would be great except having the fan switch unplugged makes the SES light come on. When the car is shut off the fan will not come back on until I jump the fan switch again.
I even wired a ground straight to the fan motor from the battery, which slowed the temperature gauge going to "hot", but did not make the fan come on.
It's not working properly because when running, the gauge just creeps to "hot", and the fan does not kick on by itself. I'm incredibly frustrated!

[danielsatur]

It sounds like a bad wire, or fan control module, I think it's located on the radiator.

[automan9482]

I will try to locate that control unit. Honestly, how many things does GM think a car needs to make the fan work??
Thanks for your suggestion!