Alternator Interface Function - GF07.10-D-1009TSA

Engine 651 in model 907 

Block diagram 

Function requirements for the alternator interface, general points 

• Circuit 87MON (engine management ON).
• Engine running.

Alternator interface, general points 

Using the alternator interface, messages are exchanged via the drive LIN between the alternator and the CDI control unit and the alternator control response is regulated. To do this, the CDI control unit reads in information from the following signals:

• Crankshaft position sensor, engine speed
• Alternator, status

Function sequence for alternator interface 

The CDI control unit controls the alternator control response, e.g. in order to reduce the charging voltage when the engine is at idle and the on-board electrical system battery is sufficiently charged.

The engine load reduced in this way causes the fuel consumption to be reduced.

The CDI control unit controls the following functions:

• Switching on of the alternator dependent on the condition of the onboard electrical system and the engine requirements.
• Regulation of the alternator based on characteristics maps stored in the CDI control unit. To do this, the charging voltage is prescribed by the CDI control unit.
• Protecting the alternator against overheating.
• Adapting the charging voltage with a delay in the event of frequent load changes at the alternator in idle to stabilize the idling speed.
• Reporting recognized errors to the instrument cluster to actuate the respective symbols and display message.

• Keep the on-board electrical system voltage at a low level and increase charging of the on-board electrical system battery in the deceleration mode (fuel saving).
• Generation of circuit 61 signal (alternator operational).

The alternator constantly performs a self-diagnosis and sends the results when requested to the CDI control unit. This compares the results with additional signals (e. g. engine speed, on-board electrical system battery voltage, time after engine start) and detects alternator faults based on this.

The following faults are identified:

• Line (drive LIN) of the alternator interface has an open circuit or the interface driver in the CDI control unit is defective (the alternator regulates to 14.3 V in this case)
• Electrical and mechanical fault on the alternator
• Control or diodes defective
• Stator interruption or short circuit
• Excitation interruption
• Charging voltage and charging current not achieved.
• Charging voltage too high
• A cracked or loose poly-V-belt

Circuit 61 signal

For alternators with alternator interface, the "circuit 61" line is omitted.

Based on the information that the CDI control unit receives via the alternator interface, the circuit 61 signal is simulated in the CDI control unit and output via the CAN network (e.g. for the instrument cluster.

Based on the information, that the CDI control unit receives via the alternator interface, the circuit 61 signal in the CDI control unit is simulated and output via the CAN network (e.g. for the instrument cluster.

Overview of system components for common rail diesel injection (CDI)

GF07.16-D-9997TSA