I have a 2003 r53 with a stubborn check engine light. All the readers I've used will connect to the bcm but not the ecu. The car does run. I'm. Wondering if anyone has had this issue.
Sofar I've replaced the ecu, checked all fuses, checked continuity between kbus line by obd2 connection in engine bay by ecu(it's good).
I've recently replaced the throttle body and added new injectors. Car was running fine until a two weeks later now it will casually cut out at idle (randomly). I've noticed holes in the exhaust but not sure if that it causing any issues. Any help is greatly appreciated

 

Are you plugged into the OBD port, and only seeing BCM info, not any ecm info ( no misfire, cat ready, temp, etc ). Can you drive, or only idle? Any P# codes to share?

 

the car runs great, the scan tool pulls up everything in realtion to bcm but will not connect to the ecu( no temps, miss fire ect) the i tek menu on number 7 will pull up engine temp. Ive even had an alternate ecu coded to the car it runs great with it installed but will still not pull engine data. I cant calibrate throttle body or anything. Kinda at a loss. Ive looked for breaks in the kbus line and found nothing.
ps. There are no blown fuses. Im connecting to the obd2 port and it trys to communicate with the scan tool but will not give me access to anything but tge bcm stuff ie raido, climate, control, lights ect

 

You don’t know the PCode, because you can’t connect? I have a 2002 Yukon XL 2500 - I lost OBD access due to a blown fuse for the cigarette lighter. Check your fuses.


https://www.northamericanmotoring.com/forums/r50-r53-hatch-talk-2002-2006/246914-where-is-the-obd-fuse-location.html

 

what code / obd reader are you using?