I recently broke off the plastic housing to a sensor bolted in the block, so I went on a search to find the replacement. I thought it was the coolant temperature sensor, so I got a replacement at CSK. Here it is...Coolant Temperature Sensor. Now I'm not so sure it's the right sensor, since the old one had one wire in, and the new one has two wires out. The sensor I'm replacing is right below the headers on the passenger side between the 6 and 8 cylinders. Reading another post below, I'm thinking I was supposed to get a temperature sender/switch. Here's a linky Switch/sender. Why is it that they have the exact same threading? Is there any way to rig the sensor to kick the fan on at a point? I'm just trying to avoid having to take the sensor out and letting my radiator shart everywhere again.

 

That part your are describing is the fan switch, on the tbi motors that is the only thing that controls the fan, the ecm is not involved. To restore proper fan operation you need to replace that switch. In a pinch you could extend that wire to inside the car and put a toggle switch connected to ground on it, then you can turn the fan on and off manually.

 

Ok...that should be the switch that grounds the secondary fan (on a two fan car.) This switch gets to a set temp (someware betwen 220 and 240 degrees) and grounds the relay and kicks on both fans.

There a a couple ways to go. First is a switch like this: Thunder Racing - Fan Switches (Engine Block) for your 1982-1992 F-Body

OR

You can connect a wire to it (should be a green wire at the switch or green with white strip at the relay). run it into the interior. connect a switch and run the switch to ground. You can then start the fans when you want.
Note: on a two fan car you have two relays. On my 88 (should be similar)
there is one on the radiator support, passanger side. this runs the fan via the ECM. One near the evoc canister on the passanger side fender. This is the one run by the temp switch. When this relay grounds BOTH fans come on full.

If i have this wrong, feel free to sing out. You can take note of my sig to see what i'm running.

Hope this helps.

 

dueling answers... check the time.