GF54.30-P-3027Q Battery Charge/Alternator Monitoring Function

GF54.30-P-3027Q Battery Charge/alternator Monitoring Function

Component Identification:

Battery charge / alternator check
If an alternator error (G2) occurs, the battery symbol and the message "Go to garage" (this message belongs to category 2) or "Stop battery/alternator." appear on the multifunction display (A1p13) in the instrument cluster (A1).
This message belongs to Category 1.
It appears when the alternator (G2) is not operating correctly (terminal 61), but the engine speed is higher than 200 rpm. There is no message when the engine is OFF.

Networking
The following CAN messages are required:
^ Terminal 61, alternator check
^ The signal "Terminal 61 (= D+)" from the alternator (G2).

The alternator check "terminal 61" is read in by the driver-side SAM control unit with fuse and relay module (N10/1).
The driver-side SAM control unit with fuse and relay module (N10/1) relays the message "Terminal 61 HIGH" (voltage at term. 61 > 9 V) or "Terminal 61 LOW" (alternator not operating correctly) on the interior CAN.

Engine speed
The pulses from the crankshaft position sensor (L5) are registered by the CDI control unit (N3/9) or the motor electronics control unit (N3/10).
This control unit sends the message "engine speed" (in rpm) on the engine compartment CAN.
The instrument cluster (A1) receives these messages and evaluates them.

Terminal 61 (= D+) alternator check
The CAN message "Terminal 61" can assume the states "High" and "Low". The state depends on the actual voltage at the input of the driver-side SAM control unit with fuse and relay module (N10/1). It becomes "HIGH" when this voltage exceeds 9 V. It is "LOW" when the voltage again drops below 4.5 volts.

Excitation current for the alternator
The excitation winding is supplied with the pre-excitation current via a resistor located in the wiring harness. When "Terminal 15R ON", the voltage at "Terminal 61" is small since the excitation winding almost short circuits the voltage.

If, when the engine is running, the alternator voltage rises above the battery voltage, the excitation winding is supplied with current by the alternator. The voltage at "Terminal 61" increases to the alternator voltage.

The "battery/alternator charge circuit" function is closely related to the "lamp check" and "engine operation detection" functions ("Terminal 61e").