Guys Im working on a 04 evo for a buddy of mine and I dont have access to the factory wire diagram. I just need an answer to one question.

I need to know if the red/white stripe with gold dot wire on the factory BCS goes directly to the ECU. Also if someone could mesure the resistance to ground on that wire at the BCS plug end and tell what reading you get with the ECU plugged up and unpluged. Thanks it would be a big help.

I think that wire on this car has a high risistance short somwhere in the harness and is giving me a boost solinoid code as soon as you turn the car on.

 

The red wire goes to the MFI relay, the other wire is the wire connected to the ecu. So you should be checking for voltage on the red wire. The ecu grounds the BCS via a transistor inside the ecu which you probably already know. I would test the BCS for fault before the wire harness unless there has been a collision.

 

Thanks thats the kind of info I need. The car hasent been wrecked but it had a AEM on it and its going back to the stock ecu. Ill let ya know what I find.