Flow chart
| element | designation |
|---|---|
| BB00 | battery |
| BF01 | engine compartment fuse box |
| BSI1 | BSI |
| CA00 | ignition switch |
| 0004 | instrument panel |
| 1150 | pre-postheating control unit |
| 1160 | pre-heater plugs |
| 1220 | engine coolant temperature sensor |
| 1221 | Diesel temperature sensor |
| 1310 | air flow meter |
| 1320 | engine ECU |
| 7020 (*) | anti-lock braking system (ABS) ECU |
| 7800 (*) | ESP ECU |
| connection number | signal | transmitter/receiver | nature of signal |
|---|---|---|---|
| 1 | request for display of the preheating warning lamp | (7020 - 7800) / BSI1 | C-CAN |
| 2 | request for display of the preheating warning lamp | 1320 / (7020 - 7800) | C-CAN |
| 3 | engine coolant temperature information | 1220 / 1320 | analogue |
| 4 | intake air temperature information | 1310 / 1320 | analogue |
| 5 | activation of the pre-postheating plugs | 1150 / 1160 | filament |
| 6 | request for display of the preheating warning lamp | BSI1 / 0004 | B-CAN |
| 7 | diesel fuel temperature information | 1221 / 1320 | analogue |
| 8 | information: Fault with the pre-postheating control unit | 1150 / 1320 | filament |
| 9 | control of the pre-postheating unit | 1320 / 1150 | filament |
Pre-heating
Role
The preheater plugs enable the temperature to rise rapidly in the combustion chambers prior to the engine being started, when starting from cold or when the outside temperature is low
Role of preheating
- To facilitate starting from cold (the air is heated up to enable the injected diesel fuel to combust more easily)
- To reduce smoke emissions (the heated air reduces the incidence of unburnt gases)
- Reduce pollutant emissions (nitrogen oxides (No.x))
NoteThe change from preheating to postheating occurs without interruption during the starting phase
Function
The engine management ECU controls the pre-post heating unit using an open cyclic ratio (OCR) signal
The pre-post heating unit supplies the pre-heat glow plugs according to the reference value calculated by the engine management ECU
Activation conditions
The preheat times are determined by the engine management ECU according to the following parameters
- Coolant temperature (measurement done by the engine coolant temperature sensor)
- Inlet air temperature (measurement taken by the mass air flow sensor)
- Temperature of the fuel (measurement carried out by the diesel temperature sensor)
- Atmospheric pressure (measurement done by the atmospheric pressure sensor internal to the engine ECU)
- Voltage of the battery
The preheating is activated when one of the following conditions is met
- Coolant temperature lower than 10°C
- Inlet air temperature lower than 10°C
- Fuel temperature below 10°C
The preheating phase ends when one of the following conditions is met
- With the engine running
- Engine not started after 25 seconds of pre-heating
- Preheat time exceeded
Post heating
Role
The post heating permits extended operation of the preheating glow plugs when the temperature of the combustion chambers does not permit combustion of sufficient quality
Role of the post heating function
- To guarantee the correct quality of combustion after starting
- Reducing the emissions of pollutants in the first few minutes after starting
- To stabilise the engine at idle
- To reduce smoke emissions
Function
The engine management ECU controls the pre-post heating unit using an open cyclic ratio (OCR) signal
The pre-post heating unit supplies the pre-heat glow plugs according to the reference value calculated by the engine management ECU
Activation conditions
The post heating times are determined by the engine management ECU according to the following parameters
- Coolant temperature (measurement done by the engine coolant temperature sensor)
- Inlet air temperature (measurement taken by the mass air flow sensor)
- Temperature of the fuel (measurement carried out by the diesel temperature sensor)
- Atmospheric pressure (measurement done by the atmospheric pressure sensor internal to the engine ECU)
- Request for engine torque
- Engine speed