OK so here i am, one of those crazy lunatics who has installed an EVO8 ECU in his 2g eclipse and am in need of a little help,,my ac works but the ECU doesn't raise idle when the ac is on,,,, go figure. i have been going over the wiring diagrams for both cars and think i have found what part of the problem is. according to the EVO FSM the ECU has wires that connect to it from the AC controls. one that goes from the control unit though dual switch then to the ECU at pin 45. the other wire goes strait from the AC control unit directly to the ECU at pin 24. there is also a wire that goes from the ECU pin 21 to the fan control module and am not sure if that is an input or an out put from the ECU. so without owning an EVO what would be the best way to figure out what signals are sent in/out of the ECU without frying something.

 

Put a continuity DMM on the the pins. The A/C output will go to ground when turned on so you can see if that matches what you see logging it The wire to the A/C Fan will be an output and also most likely pull to ground.

Have a look on the A/C threads I have elsewhere for how to log what the output is doing. If you idle is not going up then most likely the input is not being picked up. The ECU needs to know that you have requested the A/C, then it will decide if the output to the relay and fans is allowed.

I have not found how to log the input just yet, but I am working on it.

All the best!