I am trying to find out what coolant temp sensor was on the even side head (passenger) '91 TPI 5.0. It has the same wiring connector as the knock sensor. Unforunately the sensor had a catastrophic failure due to heat, and all I have left is the brass plug portion. The coolant sensor portion is more stubby and round than the ecm 2 wire temp sensor. I tried to source it through the local auto parts store

I believe there is another single wire temp sensor on odd side head as well.

Thanks

 

Thats the fan temp sensor. The one on the odd cyl bank is for your temp. gauge/light. Coolant temp is in the front of the engine, above the timing cover, threaded into the intake manifold base.

 

Thanks. you have almost cured my headache.

Is there any reason these would be difficult to source?

 

The cooland temp sensor can be bought at any auto parts store. Even the dealer can get it for you. Like stated above, the sensor in the drivers side head is connected to the gauge and just reads the temp and displays it on the gauge. The sensor sensor in the intake manifold is the primary coolant fan switch which the ECM uses to determine when the primary fan should be turned on. The 3rd sensor, in the passenger head is used to turn the secondary fan on when certain sernarios take place. I am 99% sure of my statement. I only say that because there are so many different setup thoughout the 3rd gens model years.

 

That would explain why the 2nd fan never came on...

Thanks for the enlightenment.