electric fan wiring

If anyone has the wiring diagram for a 83 528 I would be very happy. I have my girlfriends car for a couple of days and the electric fan is not coming on and need a diagram of the wiring to troubleshoot. I tried a quick test with a jumper and I now know the fan is good and the relay is getting power, just no signal from whatever temp sensor does that signalling for the fam. Can't even find that (temp sending unit) so any insight into that is appreicated too! Thanks in advance,

Mark N.
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