Combustion Preheating System DDE7.3

Combustion Preheating System DDE7.3

In contrast to the ECE version of the M57TU2TOP engine, the engine in the US project has a glow system with LIN bus connection and ceramic glow plugs.
The glow system ensures reliable cold starting characteristics and smooth engine operation when the engine is cold. The DDE control unit transmits the glow plug heating request to the combustion preheating control unit. The combustion preheating control unit puts the request into effect by activating the glow plugs by means of a pulse-width modulated signal. In addition, the combustion preheating control unit reports diagnosis and state information across the LIN bus connection to the DDE.
The LIN bus is a bidirectional data interface base on the master-slave principle, whereby the DDE is the master controller.
Each of the six glow plug circuits can be diagnosed individually.

The required glow plug temperature is determined by the DDE control unit on the basis of the following operating values:
- Engine speed
- Intake air temperature
- Fuel injection rate
- Vehicle voltage
- Status signal for starter enable

Functions
To activate glowing, the DDE sends the required glow plug temperature to the combustion preheating control unit.
The glow system has the following operating modes:
- Preheating
- Start preheating
- Start glowing
- Emergency glowing
- Hidden glowing
- Partial-load glowing

Troubleshooting
The DDE control unit monitors communication with the glow plug control unit. In the event of a fault on the bit serial data interface, the DDE control unit stores the corresponding fault code: