I have really strange issue. We are working on 2008 Cadillac STS and having issue erasing codes. I am able to read codes just fine and connect to all the other functions. As soon as I try to erase codes it gives me an error: "Erase Failure. Make sure the ignition is switched on. Check if th scan tool is securely connected to vehicle's DLC". We have tested both High Speed and Low Speed GMLAN wires going to the body control module and all of the communication grounds. We have also tried 3 different body control modules. The same error on all of them. Any ideas would be highly appreciated.

Thanks,