I've dropped an 03 Cobra engine into my 1970 Mustang. I'm using a detail zone engine harness for the car. Everything is wired up and working great, except for when I turn on my AC the engine doesn't know it's on so it idles down low and will stall out sometimes. I'm trying to understand what signal or signals tell the PCM that the AC is on so I can get it to recognize the AC is on and bump the IAC functions.
I've studied the stock 03 diagrams, and it seems like there are 3 potential places that it could see the signal and trigger the activation.
Pin 41 - 12V+ signal from the AC control dash unit saying you want AC
Pin 69 - Looks to be a ground signal coming out of the PCM, going through CCRM to trigger the AC clutch relay
Pin 86 - If I see it right, this is an open signal when everything is working correctly on the AC, but it will ground 86 when the high pressure switch is showing a fault (pressure is out of range), assume this is used to tell the PCM that it doesn't need to increase IAC functions as the AC isn't functioning.
As the car sits, it doesn't have any of these pins hooked up. I've applied power to pin 41, and it doesn't seem to make any difference to idle speed or function. Do I need 12V through 41, and also a ground signal through 69? Does 86 need anything? Or am I missing another spot that it identifies the signal?
Any help would be appreciated to get this problem figured out!
Thanks
I've studied the stock 03 diagrams, and it seems like there are 3 potential places that it could see the signal and trigger the activation.
Pin 41 - 12V+ signal from the AC control dash unit saying you want AC
Pin 69 - Looks to be a ground signal coming out of the PCM, going through CCRM to trigger the AC clutch relay
Pin 86 - If I see it right, this is an open signal when everything is working correctly on the AC, but it will ground 86 when the high pressure switch is showing a fault (pressure is out of range), assume this is used to tell the PCM that it doesn't need to increase IAC functions as the AC isn't functioning.
As the car sits, it doesn't have any of these pins hooked up. I've applied power to pin 41, and it doesn't seem to make any difference to idle speed or function. Do I need 12V through 41, and also a ground signal through 69? Does 86 need anything? Or am I missing another spot that it identifies the signal?
Any help would be appreciated to get this problem figured out!
Thanks
