Just got a rebuilt engine into my 86 FC and started it up for the first time, I quickly realized that my coolant temp gauge does not work. The wire to the coolant temp sensor (under the oil filter pedestal) is not connected which I thought would be an easy fix but for the life of me I cannot find the wire. My question is which harness does this wire come from? What colors are the wire? Really just looking for anything to help track it down.

 

its on the harness that sits on the engine and goes to the ECU, yellow wire.

i always forget it too...

 

Okay so I probably buried it under the upper intake when I put it together and thats why I can't find it. I assumed it would come from the same harness as the oil pressure sense wire...

 

its a little weird they didn't do that, the oil pressure and water temp wires go to the same place

 

I was pondering this myself. The coolant wire goes through the ECU harness and out at connector X-something (the one where the ECU meets the body harness) just to end up at the back of the cluster. Meanwhile the oil pressure, low oil switch, low coolant switch, etc all go through the body harness. And it isn't for packaging reasons because the sensors are 3" away from each other and so are the gauges.