Battery charge/alternator check, function - GF54.30-P-3027PP

MODEL 203.0 /2 /7 up to 23.4.04

Fig 1: Warning Display - Battery Charge/Alternator Check

Fig 2: Battery Charge/Alternator Function Diagram

Battery charge/alternator check

The message "BATTERY/ALTERNATOR - GO TO GARAGE", which is displayed in the multifunction display (A1p13) if a malfunction occurs, is of priority level 2 and therefore belongs to message category 2. It appears when the alternator (G2) is not functioning correctly. This is the case when "circuit 61 is LOW" and the engine speed is > 200 rpm. A message does not appear when "circuit 61 is OFF" (engine is off).

Excitation current for the alternator (G2)

The excitation winding is supplied with the excitation current via a resistor located in the front SAM control unit with fuse and relay module (N10/1). When "circuit 15 ON", the voltage at circuit 61 is low since the excitation winding short circuits the voltage to circuit 31. If, when the engine is running, the alternator voltage rises above the battery voltage, the excitation winding is supplied with current by the alternator (G2).The voltage at circuit 61 increases to the same voltage as the alternator voltage.

Networking

The following data is required from the class B (passenger compartment) controller area network bus (CAN-B) or the class C (engine compartment) controller area network bus (CAN-C):

The circuit 61 signal of the alternator (G2) (alternator check) is read in by the front SAM control unit with fuse and relay module (N10/1).
The front SAM control unit with fuse and relay module (N10/1) passes the message "circuit 61 HIGH" on the CAN-B if the voltage at circuit 61 is > 9 V.
The front SAM control unit with fuse and relay module (N10/1) passes the message "circuit 61 LOW" on the CAN-B if the voltage at circuit 61 is < 4.5 V.
The engine speed is read in via the pulses of the camshaft Hall sensor (B6/1) by the motor electronics control unit (N3/10) or the CDI control unit (N3/9) and the engine speed in rpm is passed as a message on the CAN-C.
The instrument cluster (A1) receives and evaluates this message.

Circuit 61 for alternator check

The CAN message "circuit 61" can have the status "HIGH" and "LOW". The status depends on the actual voltage at the input of the front SAM control unit with fuse and relay module (N10/1). The status is "HIGH" if the voltage at circuit 61 is > 9 V. The status is "LOW" if the voltage is < 4.5 V.

Instrument cluster (IC), location/task

GF54.30-P-3039PP