i got under the car earlier to try to find it to reconnect it...where the hell is it? i couldnt find a place anywhere to put it into...what am i looking for?

 

Your fan switch should be sticking out from the passenger side of your intake manifold. You should see a thin metal cylinder with a round plastic cover around it (the switch's female connector).

I don't know if it's any easier to get at it from below. When I replaced mine recently, pulled the plug wire off the 2nd plug from the back on the psgr side and reached down to get to it.

 

Here is a way to do the fan switch really easy... there are two wires coming off the fan itself. shave the wire until you can see the actual wire inside rap a wire around that and conect it to on off type switch...ground out the switch and you should have a fan switch that can turn on and off when you want but still work under its own power to.... make sure the shave the right wire if you shave the wrong one the fan will turn in the wrong direction..

 

i already have a fan switch hooked up to a toggle switch but im trying to fix my fan switch sensor which actually turns the fan on/off automatically

 

I'm not sure I understand the difference between "fan switch" and "fan switch sensor" -- my understanding is that there is a ~sensor sticking out the psgr side of your intake that is in contact w/coolant running by and it varies its resistance with coolant temperature. When the T is hot enough (I think Vader had a neat-o GM table re. the resistances), it lets enough voltage through and your fan should be turned on... assuming no other wiring/electrical problems - you can test for this by unplugging the connector (it has just one pin, with a plastic cover surrounding) that normally plugs into the "fan switch" and, with the key in the "on" position, grounding this connector by touching it to a clean spot of your engine/intake/whatever. If your fan doesn't come on, you have a problem beyond the fan switch.

I don't want to sound petty about terminology... I thought the definition of "sensor" was more like a device that sends info to the computer (or a guage, I guess) for an information-decision to be made based upon the value. I've just never heard the fan switch called the fan switch sensor... sorry if I'm wrong.

 

On TBI engines, the fan switch is located on the passanger side HEAD, not the intake.

 

On the TBI motors, there are three "UNITS" which monitor the cooliant temp. The "UNIT" on the driver's side head is the TEMP GAUGE Sending unit this one controls the temp gauge in the dash. On the intake next to the thermostat housing, there is a Cooliant Temp Sending unit which is where the ECM (computer) receives its cooliant temp info from. On the passenger side head, there is a Cooliant FAN SWITCH (looks like a sending unit) which will turn the cooling fan on/or off.

It could be called a FAN SWITCH SENSOR due to the fact that the unit itself must monitor the cooliant tempature which can vary in a very broad range.

 

i have an 89 305 TBI, and i can't find the fan switch sensor for the life of me. would it be easier to just hook it up to the plug going into the fan itself? if so, which wire:black or red? with the sensor, is it behind that black box behind the heater control valve?

 

i just wired in a toggle switch yesterday using left over 14 guage speaker wire, a rocker switch, and a 30 amp 12v relay from radio shack. The 240* switch still works also, but i wanted to be able to control is cause i beleive thats a little high to turn the fan on. And it only ran me 6 bucks and a days wiring (too cold for the solder to melt correctly)
~Tim

 

took me about 10min to rig my toggle switch up...just sliced the wire into the fan wire then ran it threw the firewall and put it in the radio fuse...

 

FYI, The fan switch is on the passenger side head b/w the 2 rearmost spark plugs

 

Just a comment about terminology. The one guy is right. According to automotive engineers a sensor is defined as any device that is fed to the ECM, ECU, PCM or whatever the manufacturer refers to thier onboard computer as. A switch would be any device independent of the ECM that controls a device such as a relay. I looked at the 1988 wiring for the fan control circuit and the fan switch does not feed any signal to the ECM, only is used to trigger the fan relay because a relay is needed for current requierments. I have a 89 iroc with a 5.7, and dual fans. one is controlled by the ECM, the other by a fan switch. Hope this was some help.