Alternator Interface Function - GF07.10-P-1009MNF

Engine 176.9 in model 463 

as of model year 2016 up to model year 2019 

Function requirements for the alternator interface, general points 

• Circuit 87M (Engine management ON)
• Engine runs

The circuit relay 87M(F58kN) is switched on for circuit 15 ON.

Alternator interface, general points 

With the alternator interface, messages (for example the "Dynamo Field Monitor Signal") are exchanged via the drive LIN (LIN C1) between the alternator (G2) and the ME-SFI [ME] control unit (N3/10) and the control response of the alternator is controlled.

To do this there is delayed adaptation of the charging voltage for a larger change in load of the alternator. The current operating rate of the alternator is transmitted by the dynamo field monitor signal.

The maximum data transfer rate between the ME-SFI control unit and the LIN control for the alternator is 19.2 kbit/s. The LIN control is not fitted with any direct outlets. The ME-SFI [ME] control unit reads in the following signals:

• Crankshaft Hall sensor (B70), engine speed
• On-board electrical system battery (G1), on-board electrical system voltage over circuit 30
• Alternator, status via the drive LIN

Function sequence for alternator interface 

The ME-SFI [ME] control unit regulates the control response of the alternator, for example in order to reduce the charging voltage when idling if the on-board electrical system battery is sufficiently charged.

This reduces the engine load, thus also reducing fuel consumption and reduces exhaust emissions.

The ME-SFI [ME] control unit controls the following functions:

• Switching on of the alternator depending on the condition of the on-board electrical system and the requirements from the engine
• Regulation of the alternator according to characteristics maps stored in the ME-SFI [ME] control unit. To do this, the charging voltage is specified by the ME-SFI [ME] control unit
• Delayed adaptation of the charging voltage to stabilize the idle speed when idling n order to stabilize the idle speed
• The alternator is protected from overheating
• Generation of a circuit 61 signal (alternator in operation)
• Output of the respective display message and actuation of the respective warning lamps in instrument cluster (A1)

  The ME-SFI [ME] control unit transmits the respective request via drive CAN (CAN C), powertrain control unit (N127), suspension CAN 1 (CAN E1), electronic ignition lock control unit (N73) and interior CAN (CAN B) to the instrument cluster.

• Keeps charging voltage at a low value and charges the on-board electrical system battery more strongly in the overrun modes (fuel saving).

The alternator performs continuous self-diagnosis and transmits the results when requested to the ME-SFI [ME] control unit. This compares the results with other signals (for example, engine speed, on-board electrical system voltage, time since engine start) and thus detects any alternator faults.

The following faults are identified:

• Line (Drivetrain LIN) of the alternator interface has an open circuit or the interface driver in the ME-SFI [ME] control unit is defective (the alternator regulates in this case at 14.3 V)
• Electrical and mechanical fault at the alternator:
  • Control or diodes defective
  • Stator interruption or short circuit
  • Excitation interruption
  • The charging voltage and charging current are not reached
  • Charging voltage too high
  • A cracked or loose poly-V-belt

To check the charging voltage, the on-board electrical system battery must be loaded with a battery tester since the charging voltage can be significantly reduced when the on-board electrical system battery is fully charged and under no load.

Circuit 61 signal:

Using information received by the ME-SFI [ME] control unit via the alternator interface, the circuit 61 signal is simulated in the ME-SFI [ME] control unit and issued over the CAN network (e.g. for the instrument cluster).

	Electrical function schematic for alternator interface		PE07.10-P-2709-97ZGD
	Overview of system components for gasoline injection and ignition system with direct injection		GF07.70-P-9998MNF