Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Bit-serial data interface (BSD): Notes
The bit-serial data interface is a single-wire data bus with a data transfer rate of 1.2 kBit/s.
The following components are connected across the bit-serial data interface with the DME/DDE control unit:
- Alternator (varies according to version)
- Intelligent battery sensor (depending on model series)
- Preheating control unit (for diesel engines before introduction of the engines N47/N57)
- Electric coolant pump (depending on variant)
- Oil condition sensor (depending on variant)
Only DDE control unit: Each component connected across the BSD is connected to its own pin on the DDE control unit.
However, these pins are interconnected in the control unit.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.