On my 1999 300M the head lights quit working, the tail lights quit working, the
power locks quit working, the internal heater blower motor runs on high full
time, the switch does not matter what position it is in. Gas gauge quit working, and wind sheild wipers and
all digital display on the trip computer & heater console has no information
displayed
car starts and run but can.t figure this out checked all fuses and relays which bcm control all these controls

 

module at the fuse box under dash does this control all my problems with control voltage

 

have u gotten a wire diagram and traced down all of the items that u have issues with see what is common between them.

 

No i dont have a good diagram ,the Haynes is not good enough not much info