I recently bought an '02 MCS which had extensive electrical mods by previous owner(s), including aftermarket radio, speakers, sprint booster, Bluetooth OBDII reader, and boost gauge. Not needing these mods, I removed them, and may have now created many gremlins.

The car starts and runs fine. The electrical systems, including door locks, windows, headlights, parking lights, wipers (F & R), turn signals, cruise control, etc. function initially, but they all shut down after a few seconds - the engine continues to run.

AutoLogic diagnostics by local service shops indicate Body Control Module malfunction. They have swapped it twice with a known functioning unit of the same vintage, and problems persist.

I cannot feed the diagnostic and gremlin-chasing labor any longer. Currently contemplating putting up the car for Part-out; selling the car, with these known problems, is not an option. Before taking this drastic action, I would appreciate any relevant experience and solution you can share with me.

 

I would recommend scanning all the control modules in the car for errors, there could be an issue with the CAN-bus that's caused by a faulty module other than the BCM. If you can post all the error codes in all the modules that would be helpful.

Also, keep a close eye on the voltage of the electrical system for the few seconds after the engine is started. If there's an issue with the alternator or voltage regulator it can cause all sorts of weird electrical gremlins to appear. Also try to monitor the voltage at the BCM too (the Aautologic scanner can do this).

 

I don't have an 02 Electrical Manual, but if I were troubleshooting this, I would first look at where all of those aftermarket accessories were tapped into the system. One of those wires might have been broken. A lot of people "Scotch Lock" connections which cut the wire, but as long as the scotch lock stays in, its fine, its when you take it out that problems begin. Also, since all of these components shut down at the same time, I would be following a common Ground. The boost gauge, OBDII reader, and Sprint booster are most likely not the culprits. It is highly likely the stereo or speakers are. Stereos are typically installed on the body controls interior system for power and ground. A good stereo installer installs his own power and ground straight to the fuse box with relays instead of tapping into wires (unless there is a PnP adapter). Look at those connections and make sure they are factory, inspect closely for pinched wires. Ohm out all of the circuits from the BCM to the components you listed. Chances are it will lead you to the faulty circuit. It doesn't sound like your BCM is bad, but rather it is loosing power or ground OR it has a broken wire that just doesn't supply enough power.

 

Mebean and Brutal-Force,

Thank you fof your suggestions. I have passed them on to the tech, and will apprise of progress if/when it is achieved.