I first noticed a problem walking up to my '03 MCS after lunch to find it unlocked. Got in, drove away and it kept trying to lock once I passed 10MPH. It would repeatedly lock/unlock. Got to work and tried to lock it to go inside; no luck. I'd lock it and it would unlock. Left it unlocked for the afternoon. Came out to go home and heard the lock motors clicking. The whole drive home they were clicking/whirring, even the gas cap lock. Got home and pulled the fuse to spare the wear and tear on the actuators. But, I noticed the interior lights kept cycling on and off, even after a manual override. It's like someone's playing a bad joke on me. Pulled the interior lights fuse to save the battery. Any thoughts on what the problem could be? I read in another thread about a faulty driver door actuator. That may be it because occasionally it would chirp when I tried to lock it with the key fob, as when the driver door is left open and you try to lock it remotely. Help! It's practically unusable in its current state.

 

I guess no one else has had this problem. Resolution: BCM (Body Control Module) = $1100 = Locks/lights working again. Bonus: I now get chirps when I lock/unlock the car but the DRL's seem to be on any time the car is running as opposed to just when the e-brake is off.

 

Sorry that you had to pay that much for it... but you can reprogram the DRL and other stuff with NCS expert... if you have any inclination to do so.