Handles commands for windshield wipers and other cabin accessories.
While the car is running, the BSM B3 is managing dozens of tasks simultaneously: siemens bsm b3 schematic work
. You can usually replace a B3 with a B5, as the B5 contains all the relays of the B3 plus extra for features like headlamp washers. You always downgrade from a B5 to a B3. ⚠️ Safety Warnings De-energize Handles commands for windshield wipers and other cabin
This "slave" integrated circuit is the heart of the relay switching logic. The main processor cannot handle the high current needed to activate relay coils directly, so it sends a low-current signal to the ULN 2003, which then acts as a bridge to trigger the relays. The Processor: siemens bsm b3 schematic work