: Electrical problem.

11-15-11, 08:56 AM
When I am driving my car and use either the OnStar feature or use an auxillary device plug in, then park my car it won't start without a jump. Then it runs great, until the next time I use one of these functions again.

11-15-11, 09:48 AM
Your battery is SHOT!

Have it Load Tested to be sure, but my bet is that it's just time for a new one....

11-15-11, 12:20 PM
Someone mentioned BCM module. Do you know what that is?

11-15-11, 06:06 PM
Body Control Module. Don't think this would be your problem. To my knowledge the BCM cannot shut down the engine. I senses anti-lock brakes, stability system and traction control.

11-16-11, 12:17 AM
There are (usually) in excess of 20 modules in the 2005+ STS (depending on your options). BCM is somewhat of a generic term by current standards. Your VCIM (OnStar) module is only one of many. Your radio is in essence a "module" also as it is a component that performs a function and communicates on the data bus. Other modules in the car include one in each of your four doors, your instrument panel module, instrument cluster, XM receiver module, driver door switch module, climate control module, suspension control module, remote control door lock receiver just to name a few. These all work both collectively and of course independently. We're well beyond the days of one BCM in addition to the ECM. What you're describing is very unlikely a module. Try your battery first (load testing).