Here's some background first. I purchased a 2004 GTO w engine harness. The engine is in the car and ready to be wired up. I installed a 1-wire Sanden AC. To get the original engine harness wired properly, I sent the harness off to a guy to do the work But I'm not 100% sure he knows what is going on. Here is his latest comminication w me:

"Ok this what I found out. Your a/c system has to be wired your it standalone system so what ever system your running you got to hook it up it way. Also for your fans on the engine your going to have to put a temp sensor switch in the engine to run them because their no wiring and the ecm for them."

To my knowledge, the ECM DOES have the capability to turn the HI/LOW fans on. Is there something I'm missing here?

 

Better get a free GTO Repair Manual here (follow the directions- just click download); it will have the wiring diagrams: http://www.ls1gto.com/forums/showthread.php?t=736178

 

Unfortunately, I've looked at wiring diagrams for this engine and am totally puzzled. I do see wires from the ECU marked hi/low fan. Any ideas?