GF07.16-P-3022OHL | CDI alternator interface, function | 5.5.08 |
ENGINE 642.9 in MODEL 221.0 as of Model Year 09 /Modification Year 08
ENGINE 642.9 in MODEL 221.1 as of Model Year 09 /Modification Year 08
General function requirements
Circuit 61 ON
Common rail diesel injection (CDI) alternator interface, general
Messages are exchanged between the CDI control unit CDI (N3/9) and the alternator (G2) via the alternator interface.
The exchanges take place over the drive LIN (LIN C1).
The CDI control unit actuates the following functions:
Function sequence: regulation of the alternator
Function sequence: generation of the signal "circuit 61 ON"
Function sequence: diagnosis
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Function sequence: regulation of the alternator
Through the alternator interface, the CDI control unit sets the alternator control response, for example, in order to reduce the charging voltage at idle when the on-board electrical system battery (G1) is sufficiently charged. The reduced engine loading means that less fuel is consumed and exhaust gas emissions are improved.
At high load changes on the alternator in idle the regulation voltage is adjusted with some delay by the CDI control unit and thus the idle speed stabilized.
Function sequence: generation of the signal "circuit 61 ON"
For alternators with an alternator interface, line
"terminal 61" is not needed. Using the information received by the CDI control unit through the alternator interface, the "tml.-61 signal" is replicated in the CDI control unit and placed on the chassis CAN.
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Function sequence: diagnosis
The alternator constantly performs a self-diagnosis and sends the results when requested to the CDI control unit. The CDI control unit compares the results with other signals (e.g. engine speed, battery voltage and time after engine start) and detects the following faults:
- Short circuit or open circuit on output "tml. 61" of CDI control unit
- Open circuit on alternator interface line, or fault in interface driver of CDI control unit
- Electrical and mechanical fault on the alternator
In order to check the regulation voltage, the on-board electrical system battery must be loaded using a battery testing device since the regulation voltage can be reduced significantly by a full and under no load on-board electrical system battery.