I have replaced my cooling fan relay along with the cooling fan relay wiring harness on my 89 Camaro RS. I have also replaced the thermostat and temp sensor. About a week ago the cooling fan stopped working, even with the AC running which of course caused the engine to start overheating again. The new relay and wiring harness comes with 5 wires (all white) but the slots are labeled on the back of the wiring harness. On the old relay/wiring harness only 4 wires/slots were used (no 5th wire at all) so what do I do with the extra wire on the new relay/wiring harness? I do not have it running to anything but my fan is still not coming on. Could this wire need to be utilized in order for the fan to work? Thanks in advance.

 

Probably not.

The 5 wires are the 2 for the coil, plus 3 for the relay contacts. The relay is a "change over" configuration, whereas a 4-wire one is only a "make" configuration. The 5th wire is for the normally closed contact... i.e. it would get power when the relay is NOT operated, and power will go away when the relay IS operated. The normally open contact gets power only when the relay IS operated and NOT when it's NOT, which of course is the logic you want for the fan. The 5th wire is pretty much useless in this situation.

Check that the relay is getting the command to operate when it should; that is, that there's 12V between the 2 coil wires when the temp is above the set point of the switch. The relay should click when it operates, if you have any convenient way of doing that. (for example, by having your assistant short the temp switch wire to ground while you listen to and measure voltages at the relay) Check the 12V supply to the contacts and make sure it's always there, then check the 12V that should be getting sent to the motor.

 

oops

 

Sorry, had a weird mental lapse...
If yours is the single fan there are 4 wires going to the fan relay. One fat one from B+ is reddish or orange. Two small wires, one tan or gray for 12v with key on and the green with white stripe one that provides the ground to make the relay send 12v back down the big black with red stripe wire to the fan to turn it on .If that's all connected right that should do it. On the V8s the green with white stripe wire comes from the fan switch in the passenger side head that sometimes fails, but there is also another green with white stripe wire that turning on the AC will send the ground on to do the same thing.

 

Awesome thanks for the info. I will get a chance to check it out tomorrow and let you know.