Hi i'm Joe brand new to this site,(Backstory) i bought an 89 iroc-z (5.7L V8 5-speed) back in march that had been sitiing in a driveway under a car cover for 5-10 years and was not running when i received it. The PO said that the only problem was that I needed a new radiator fan because it is broken, so anything 60mph+ im fine anything below that without the heater going the temp rises and does not come down. So i know like he said the fans are not working. I tested both fans directly hooked up to the battery and they both work fine, changed relay's, looked at wires and fuses, i grounded the CTS next to oil dipstick and heard a relay click but from under the car the click came from the battery area where there is two more relays but im not sure about that. Ive been searchng this problem weekly since march on any forum i can find to no avail. I'd rather not wire in a manual switch as it is last resort. Thankyou for the help in advance

 

Don't wire up a switch, if anything else wire up a new relay and use the switch in the head to ground the coil.

It sounds like you need to go find out what is clicking when you ground the sensor wire. Who knows what a previous owner did.

 

For 1989 this schematic should be correct



I don't think you looked at all of the wires/fuse(s)/Relays in the coolant fans circuit, if you had than there would be no problem. Right?
There is a fusible link that may have burned out. You can purchase one from any autoparts store in the wiring isle.
Check the factory fuse in the fuse panel.
Check the relays by removing the pigtail from the relay and using a jumper (small length of wire) to wire the incoming power wire (Orange) to the outgoing power wire (Black with red stripe). The orange wire is hot at all times so there should be power there. the Black wire should always be a ground. If the fan turns on it was probably a relay issue. If it still doesn't turn on it was a bad fusible link (assuming the previous owner didn't add in any wiring/switches).

 

Do you have AC? do the fan(s) turn on with the AC turned on? IF they do, the overall circuit is fine, meaning it's not a fuseable link in the wiring because this bypasses the relay. Car hits temp, fan temp switch grounds sending the ground signal to the relay. Relay flips, sending power to the fans.

I mean the single fan system is easy. You already ruled the fans good. So it has to be 1. Wiring, 2, relay, 3. fan switch. 4. Combination of the three.


Turn the car to run, ground the wire going to the fan switch in the passenger head. Does the fan turn on? If it does, it's the switch in the head. If it does not, could be the relay or the switch. Swap the relay and try again, making sure everything is seated. Ground the wire and if it runs, the relay was bad. Hook it up, run it up to temp. does the fan turn on? If it does, all good. If not, replace the switch.

On my car, the harness where the relay plugs in wasn't seating all the way causing the relay not to trip (found this out after 2 new relays went in).