S07.10-0027-79
Block diagram |
A1/1 | Instrument cluster (KI) control unit | N93 | Central gateway (CGW) | |
B95 | Battery sensor | CAN HMI | User interface CAN | |
B70/2 | Crankshaft Hall sensor | CAN V | Vehicle CAN | |
G1 | On-board electrical system battery | PWM | Pulse width modulation (signal) | |
G2 | Alternator | A | Mercedes-Benz | |
N3/33 | CDI control unit | B | Nissan | |
N14 | On-board electrical system management system control unit | C | Default | |
N50 | Fuse and relay module control unit (SRM) | D | Optional |
Function requirements for the alternator interface, general points
Circuit 87 ON (engine management ON)
Engine running.
Alternator interface, general points
Information is exchanged between the alternator (G2) and the fuse and relay module (SRM) control unit (N50) over the alternator interface. This information is sent for alternator control via the vehicle CAN (CAN V) to the ME-SFI control unit (N3/33).
Function sequence for alternator interface
The status of the alternator (G2) is transmitted over the alternator interface to the fuse and relay module control unit (SRM) (N50) and from there via the vehicle CAN (CAN I) to the CDI control unit (N3/33).
The vehicle power supply management system control unit (N14) receives from the battery sensor (B95) the status of on-board electrical system battery (G1) and sends it to the CDI control unit (N3/33).
The CDI control unit (N3/33) also receives the engine speed from the crankshaft Hall sensor (B70/2).
The CDI control unit (N3/33) transmits the "engine running" signal and the alternator request via the vehicle CAN (CAN I) to the fuse and relay module control unit (SRM) (N50). The target voltage is then prescribed to the alternator (G2) over the alternator interface.
Delayed adaptation of the charging voltage occurs in the event of frequent load changes at the alternator (G2) when in idle to stabilize the idling speed.
The alternator (G2) permanently performs a self-diagnosis. The results are transmitted over the alternator interface to the fuse and relay module control unit (SRM) (N50) and from there via the vehicle CAN (CAN I) to the ME-SFI control unit (N3/33). This compares the results with other signals (for example, engine rpm, on-board electrical system battery voltage (G1), time since engine start) and thus detects any alternator faults (G2).
The following faults are identified:
Control or diodes defective
Stator interruption or short circuit
Excitation interruption
Charging voltage or charging current too low
Charging voltage too high
A cracked or loose poly-V belt
Recognized errors are transmitted by the ME-SFI control unit (N3/33) via the vehicle CAN (CAN I) to the instrument cluster control unit (IC) (A11), which reacts by issuing the respective message.