I bought a huge project that is a 85 iroc body lt1/t56 drive train with a painless wiring harness. The wiring harness uses the ecm from a 95 camaro, it does not have any wiring for cooling fans so i looked up the pinouts for the ecm and added the two wires i needed to turn the cooling fans on. The pins are 10 and 11 on the red connector and from what I read says the ecm supplies the ground. The ecm is connected to the temp sender on the water pump and the sender appears to be working but the pin 10 or 11 on the red connector never shows ground with a meter after the temp reaches grater than 220, is there anything other than the water pump temp sender that the ecm is looking at to turn the fans on?

 

I think the AC switch is figured in there somehow. After I deleted the AC, my second fan didn't come on. ....didn't find it until I began digging around on how to control my fans with the Holley HP system, so I never had to figure out the exact details of it, but you might start there.