I have recently purchased a 1986 IROC Z28 with a Tuned Port Injected 305 ci engine. I need to replace the radiator fan switch and I can not find it on the engine. The switch is a one wire thermo type switch with a round lug. I hope one of you can tell me where it is located. I have have looked all over the heads and intake manifold and the only one wire sensor I can find is the knock sensor down by the starter. I have a chilton manual and it does not show the location of the radiator fan switch.

 

There is no thermo fan switch. The fan is controlled by the PCM (computer) via the fan relay. There is an ETC (Engine Temp Sensor) which sends coolant temp data to the PCM. The ETC is mounted on the front of the intake manifold and has 2 wires connected to it (Yellow and Black)

 

CHECK THE SWITCH ON THE SIDE OF THE PASSENGER HEAD BETWEEN THE NUMBER 2 AND 4 PISTON. AND YOU WILL FIND IT. IT PRETTY HIDDEN SO DONT GIVE UP TO QUICKLY.

 

Thanks for the information.

 

I have replaced the fan swith with the two wires and the fan still does not come on. I can only get it to come on when I turn on the A/C. I have replaced the ECU, could the PROM be bad? Do they make a PROM that will make the fan come on at a lower temperature?

 

i had the same problem.. except it made a couple other thing go crazy to.. but it turnedd out to be ground issue.