I have a 1991 TA, 305 TPI, Auto. I was under the car and looking for the fan switch in the passenger side head between #7 and #8. I was suprised to find a threaded plug instead of the switch. The knock sensor is there and plugged in, but there is another wire with connector just dangling not hooked to anything. I have a new fan switch to turn on at 200 degrees ready to install.

Can I remove the plug and install the switch?? Or will it even work?? The wire connector that is currently unhooked fits the switch prefectly. I am wondering if the wire was for a different knock sensor and the 91's didnt use the switch or has it been removed by a previous owner?? The wire to the knock sensor is dark, looks black. The unattached wire looks tan, but could be white and just discolored. I have searched the forum and found a lot of conflicting information about wire colors, fans being controlled by ecm, and the differences between early and late model setups. Just want some advice before continuing.

Thanks!!!

 

Take the wire, with the key ON, and ground it - if the fan comes on, then that's the right wire. If is doesn't. either the PO has rewired the fan some how, or it's the wrong wire.

 

A dangling sensor prolly means it was installed once upon a time. If it fits, it fits! Put your new one in and see what happens. All the cars had a fan switch between 6 and 8 cylinders.

 

The knock sensor and the fan switch use the exact same kind of connector.

 

Quick update. I was able to remove the cap/plug with an 8mm hex socket. I installed the fan switch and plugged in the unused single wire connector. Next I started car, refilled and "burped" the coolant system to remove air. The fan on the passenger side did turn on at approx 200 degrees. Still don't know why there was no fan switch, but all is good now.

Thanks for the help guys!!