Electrical Gremlin....crash mode??
 

Okay here's the symptoms
02 4.6IS

The X has been locked as normal. I unlock using either remote or key in door. When I start her up, the hazard lights come on, the dome light forward of sunroof (not the reading lights) come on, and all doors unlock.

There is no pattern that I can identify. Sometimes its cold out, sometimes warm. Sometimes it's been locked all night. Sometimes I've left it for 4 minutes. Key unlock or remote. Key lock or remote lock.

Sometimes it will go for a week without doing it. then it will do it two days in a row. sometimes it will go 30 key starts without a problem, then it will do it twice in 10 or 12 starts. Sooooooooo random.

Battery is new. Alternator is new. Belts are new. No codes show up on scan tool.


The only hint I have so far is that apparently when the X detects a collision (not sure how severe) it activates the hazard lights, puts the interior lights on and unlocks the doors automatically. Does anyone know anything about the crash mode? What would trigger it? What would cause it to think it's in that mode? a sensor? a module? a programmed code in the BCM?

Where the heck do I start?

I have clarified that in fact all interior lights come on, not just the front dome light.


Anybody know anything about this "Crash mode"

ignition switch?

bad battery potentially. check the voltage of it when it is sitting for a bit. Bad batteries do VERY odd things to electrical systems of BMW's

It does sound like crash mode. Crashes are sensed by the Airbag module and then a message is send across the K-bus to all the other modules. In the older cars the is a wire that runs from the airbag module to the general module (to set interior lights and unlock doors) and to the Light Control moddule (to set the hazards) . I'm not sure which method is used in your '02.

You may need to have it "scanned" by the proper BMW scan tool or the like. The usual OBD II scanners will not pick up special codes. I'm thinking of something such as the LKM going faulty and having fault codes stored in (I'm told) the Dash Fault Memory. When my LKM was going it did all sort of weird things with lights and it took the dealer a week to diagnose because they did not know where to look for the codes. The fault would not appear for the dealer until the did a prolonged road test. (1.5 hours of driving.) They were ready to hand it back to me with "No Fault Found" but I insisted they keep it until they repaired it or explained why the vehicle was giving every appearance of being possessed.