BMW 3 Owners & Service Manuals

BMW 3: Low-voltage connections

In the low-voltage connector at the Electrical Machine Electronics the following lines and signals are combined:

  • Terminal 30 from the hybrid power distribution box
  • Terminal 30 from the front left power distribution box
  • Terminal 30C (terminal 30 crash signal)
  • Ground
  • FlexRay bus system
  • PT-CAN bus system
  • K-CAN 5 bus system
  • Input and output of the circuit of the high-voltage interlock loop (EME control unit evaluates the signal and initiates a shutdown of the high-voltage system in the event of an interruption to the circuit. Redundancy of battery management electronics (SME) )
  • Actuation of the shutoff valve in the vehicle interior
  • Activating the electrical vacuum pump
  • Evaluation of the rotor position sensor at the electrical machine
  • Evaluation of the temperature sensor at the electrical machine
  • Intelligent battery sensor of auxiliary battery (LIN bus).

The Electrical Machine Electronics is connected to the 12 V vehicle electrical system (terminals 30 and 31) via two separate low-voltage connections and lines with large cross-sections. Via this connection the DC/DC converter in the Electrical Machine Electronics provides the entire 12 V vehicle electrical system with energy. These two lines are connected with the Electrical Machine Electronics via a screw connection.

The following graphic summarizes the low-voltage connections of the Electrical Machine Electronics in the form of a simplified wiring diagram:

G20 PHEV, low-voltage connections of the Electrical Machine Electronics

  1. Electric Motor Electronics (EME)
  2. Output stage for activating the combined expansion and shutoff valve
  3. Terminating resistor, FlexRay
  4. Signal lines of the high-voltage interlock loop
  5. Electrical machine (entirety)
  6. Temperature sensor
  7. Rotor position sensor
  8. Safety Battery Terminal (SBK)
  9. 12 V battery
  10. Intelligent Battery Sensor (IBS)
  11. Electrical vacuum pump
  12. Output stage for the activation of the electrical vacuum pump
  13. Unidirectional DC/DC converter
  14. Intelligent Battery Sensor (IBS2)
  15. Additional 12 V battery
  16. Safety Battery Terminal 2 (SBK2)
  17. Combined expansion and shutoff valve (interior)


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