Cadillac Repair Questions? Ask a Mechanic for Answers ASAP
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To be honest, communication errors or serial bata lines can be tricky to diagnose, especially online and if the owner doesnt have a full function scan tool for testing. Because there are issues with the theft deterrent and the windows, I more suspect the BCM is faulty, and if you have a Tech2 scan tool, I can walk you thru the needed testing