How do I add an air temp sensor to my '91?

[John B]

I am getting a cal that requires an air temp sensor. I have the parts I need, sensor, pigtail, T2 intake, but where do I patch in the two wires from the sensor?

[turbovanman²]

You need to run a wire to the computer, pin #21. You need to get another harness or part of one, as you need the little wiring pin. Drill out the hole in the ecm connector and insert your new pin. Run the wire to the sensor. The ground side should be wired into the other sensor grounds, I used the TPS and IAC grounds.

[John B]

Great! But where can I find a diagram of the pin numbers?

[turbovanman²]

Great! But where can I find a diagram of the pin numbers?

I believe there numbered on the plug, so just count to 21, If you look at the plug-ECM side, it starts with #1 on the upper left, then goes left to right. #21 is under #1, the first pin on the 2nd row.


The ground wire colour is black/Lt blue. Pin 21 is between #20-Dk green alt wire and #22 is Org/Dk Blue and is the TPS signal wire.

[John B]

Thanks Simon, that's a big help.