Alternator interface function - GF07.10-P-1009MMA
ENGINE 157.9 in MODEL 212, 218 up to model year 2014
ENGINE 278.9 in MODEL 207, 212, 218 up to model year 2014
Function requirements for the alternator interface, general points
- Circuit 87M (engine timing ON)
- Engine running
Alternator interface, general points
Using the alternator interface, messages are exchanged via the drive train LIN (LIN C1) between the alternator (G2) and the CDI control unit (N3/10) and the control response of the alternator is controlled. The ME-SFI [ME] control unit reads in the following sensor and signals for this purpose:
- Crankshaft Hall sensor (B70), engine speed
- On-board electrical system battery (G1), on-board electrical system voltage via "Circuit 30"
- Alternator, status via drivetrain LIN
Function sequence for alternator interface
The ME-SFI [ME] control unit controls the alternator control response, for example, in order to reduce the regulation voltage (charging voltage) when the engine is at idle and 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 on-board electrical system voltage and the demands from the engine.
- Regulation of the alternator according to characteristics maps stored in the ME-SFI [ME] control unit. To do this, the regulation voltage is preset by the ME-SFI [ME] control unit.
- Adapting the regulation voltage with a delay in the event of frequent load change at the alternator when idling to stabilize the idling speed.
- Protecting the alternator against overheating.
- Generating a circuit 61 signal (alternator in operation).
- Recognized faults via the chassis CAN (CAN E) to the instrument cluster (A1) for actuation of the respective warning lamp and display messages.
- Maintains the regulation voltage at a low value and arranges increased charging of the on-board electrical system battery in the deceleration phases (fuel saving)
The alternator performs continuous self-diagnosis and sends the results when requested to the ME-SFI [ME] control unit. The control unit compares the results with other signals (for example, engine RPM, on-board electrical system battery voltage, time since engine start) and thus detects any alternator faults.
The following faults are identified:
- Line of the alternator interface (drive train LIN) has an open circuit or the interface driver in the ME-SFI [ME] control unit is defective (the alternator regulates in this case to 14.3 V)
- Electrical and mechanical fault at the alternator:
- Control or diodes defective
- Stator interruption or short circuit
- Excitation interruption
- Regulation voltage and charging current not achieved
- Regulation voltage too high
- A cracked or loose poly-V belt
Diagnosis
To check the regulation voltage, a battery tester must be used to place a load on the on-board electrical system battery, as the regulation 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 over 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 IC).
| Electrical function schematic for alternator interface | MODEL 207 | PE07.10-P-2709-97EAH | |
| MODEL 212 | PE07.10-P-2709-97DAI | ||
| Model 218 | PE07.10-P-2709-97XAB | ||
| Overview of system components for gasoline injection and ignition system with direct injection | ENGINE 157.9 in MODEL 212, 218 up to model year 2014 ENGINE 278.9 in MODEL 207, 212, 218 up to model year 2014 | GF07.70-P-9998MM |