Cadillac CT5 Door Lock System Complete Failure

Had the same electrical issue on my 2020 Cadillac CT4. The door sensor system completely failed to detect open/closed status, causing problems with both the central locking and interior lights. A regular mechanic initially checked it, but the problem required dealer diagnostics to properly identify the issue. The main door switch wiring harness had corroded connector pins, plus a faulty door sensor module. These electrical components needed specialized testing equipment to diagnose accurately. The repair involved replacing the main door sensor control module and rewiring several connector plugs. This was definitely a serious electrical issue that could have potentially affected other systems if left unaddressed, including the car alarm functionality. The job took about 4 hours total, and the dealer had to program the new module to sync with the car's computer system. Regular shops typically dont have access to this programming capability. Given the symptoms you describe, particularly the complete failure of all door detection, its likely youre facing a similar central module issue rather than individual door switches. Would strongly recommend going directly to the dealer to avoid multiple diagnostic attempts.

Thanks for sharing your experience with the door sensor problems. Sounds exactly like what Im dealing with, especially the part about automatic locks failing completely. Quick question: do you recall roughly how much you ended up paying for the full repair? Just want to get a sense of the costs since these vehicle door issues can get expensive when they involve multiple components. Also curious if youve had any other door latch or car sensor problems since getting it fixed?

Thanks for asking about the costs. The situation with my door contact signal was actually less severe than initially thought. After seeing the dealer mechanic, they found a loose electrical connection at the main door wiring harness. The faulty door contact signal was resolved by repairing the cable and cleaning the plug connection, which came to 95€ total. No other door latch or electrical issues since the repair. The vehicle doors have been working perfectly for the past months, with all sensors properly detecting open and closed positions. The dealer mechanic mentioned these problems often stem from simple connection issues rather than complete module failures, despite similar symptoms. The diagnostic process was quick once they had the right testing equipment to trace the exact location of the disrupted contact signal. Much better outcome than having to replace the entire door switch system or sensor modules.

Just got back from the dealer and wanted to update everyone. After the diagnostic check, they found my automatic locks were failing due to a corroded main door sensor module, pretty much what others mentioned here. Total repair cost hit 780€ including parts and labor. The mechanic actually showed me the damaged component. The contact signal unit was completely shot, and several door latch sensors needed replacing. They had to reprogram the whole system after installing the new parts. Took about 5 hours total but everything works perfectly now, all vehicle doors lock and unlock properly. What a relief to have this fixed. The service advisor mentioned these issues are pretty common in newer models with complex door sensor systems. At least now I know what to watch for if anything starts acting up again. Much better experience than my last repair shop visit.