This is all on a 1991 Dual Fan GTA Hey everybody. I was wondering if anyone could tell me a little more than I seem to be finding about the sensors in my cylinder heads. I have searched this for the past 2 hours, I cant sift anymore threads to find. What I have gathered so far is that the passenger side sensor is the input for the fans, and the drivers side sensor is for the dash gauge. Now what I wanted to know is if either of these fans has anything to do with the ECM controls for tuning? I have to figure they do. My thing is I smashed the passenger side one haha. Anybody?

The passanger side sensor controls the second fan only, the primary fan is controlled by the sensor under and to the right of the intake where the intake meets the throttle body (yellow and black wires i think). The driver side manifold sensor only runs the gauge in the dash just as you said.

heres a picture of the general area for the primary fan sensor, its to the right of the circled sensor (best pic i had of this area sorry).

So your saying the sensor near the water neck in the one that inputs to the ECM?

Yes thats correct, it connects to the ECM and controls the primary fan. You can test this by jumping that connector, when you jump the connector to that sensor your primary fan should remain on 100% of the time and you'll get a SES light for engine temp. It's a coolant temp. sensor