General synoptic diagram of the diesel fuel injection ECU
| BSI | built-in systems interface |
|---|---|
| 0004 | instrument panel |
| 1115 | cylinder reference sensor |
| 1120 | knock sensor (accelerometer) |
| 1150 | pre-heater control unit |
| 1160 | pre-heater plugs |
| 1211 | fuel gauge |
| 1220 | engine coolant temperature sensor |
| 1221 | diesel fuel thermal sensor |
| 1233 | turbocharger pressure regulation electrovalve |
| 1253 | EGR solenoid valve |
| 1261 | accelerator pedal position sensor |
| 1276 | electric diesel fuel heater |
| 1277 | low pressure actuator (IMV) |
| 1310 | air temperature and air flow meter |
| 1312 | inlet air pressure sensor |
| 1313 | engine speed sensor |
| 1320 | engine ECU |
| 1321 | Diesel high pressure sensor |
| 1331 | no. 1 cylinder injector |
| 1332 | no. 2 cylinder injector |
| 1333 | no. 3 cylinder injector |
| 1334 | no. 4 cylinder injector |
| 2100 | principal brake switch |
| 2101 | Redundant stop switch (vehicle with ESP) |
| 4050 | sensor for presence of water in diesel fuel |
| 7306 | clutch pedal switch |
| 7308 | secondary brake switch |
| 8009 | linear pressure sensor for the air conditioning fluid |
| no. of link | signal | nature of signal |
|---|---|---|
| 1 | camshaft position information | open cycle ratio (OCR) |
| 2 | combustion noise information | analogue |
| 3 | engine coolant temperature information | analogue |
| 4 | diesel fuel temperature information | analogue |
| 5 | accelerator pedal position information | analogue |
| 6 | inlet air quantity information | analogue |
| inlet air temperature information | analogue | |
| 7 | inlet air pressure information | analogue |
| 8 | engine speed information | open cycle ratio (OCR) |
| 9 | fuel pressure information | analogue |
| 10 | redundant brake pedal switch (vehicle with ESP) | all or nothing |
| 11 | water in diesel fuel information | all or nothing |
| 12 | clutch pedal information | all or nothing |
| 13 | redundant brake pedal switch, with: cruise control | all or nothing |
| 14 | air conditioning circuit pressure information | analogue |
| 15 | control for pre-heating unit | all or nothing |
| 16 | control of pre-heater plugs | all or nothing |
| 17 | turbocharger regulation electrovalve switch | open cycle ratio (OCR) |
| 18 | control of EGR (exhaust gas recycling) electrovalve | open cycle ratio (OCR) |
| 19 | control of the ECU earth for supplying the fuel heater | all or nothing |
| 20 | low pressure actuator control (IMV) | open cycle ratio (OCR) |
| 21 | control of the 4 diesel injectors (PULSE) | open cycle ratio (OCR) |
| 22 | fuel level information | analogue |
| 23 | fuel level information | multiplexed signal (Comfort VAN) |
| 24 | brake information | all or nothing |
| 25 | request for lighting of the warning lights on the instrument panel | multiplexed signal (CAN) |
| 26 | fuel gauge information | multiplexed signal (CAN) |
Injection ECU (1320)
Role
The ECU controls the whole injection system
The ECU software incorporates the following functions
- Check functionalities of injection and pollution control
- Driving improvement strategies
- Engine immobiliser function
- Emergency strategies
- Fan unit and warning lamp operating management (*)
- The diagnostic with memorisation of failures
- The cruise control function (*)
(*) according to specification
The ECU ensures the electrical control of the following elements
- Diesel injectors
- High pressure fuel regulator
- Fuel flow actuator
- Recycling regulation electrovalve (EGR)
- Pre and post-heating control unit (post-heating cut-off)
The ECU supplies the following information
- Current consumption: to the on-board ECU
- Air conditioning cut-off
The atmospheric pressure sensor can not be separated from the injection ECU
The ECU has 2 power stages able to supply the very high control current necessary for operation of the diesel fuel injectors
The injection ECU software is updated by downloading (ECU fitted with a flash EPROM)
Description
Connector CME (32-way grey)
Connector CMI (48-way brown)
Connector CH (32-way black)
The injection ECU is linked to the injection harness by 3 modular connectors
Connector assembly order
- Grey connector
- Brown connector
- Black connector
Battery (BB00)
The charge level of the battery is important for the HDI direct injection system to operate
WarningA battery voltage of less than 7 volts disturbs the operation of the HDI direct injection system
The ECU memorises a fault in the following cases
- Battery voltage greater than 18 volts
- Battery voltage less than 6,5 volts
Engine fusebox double injection relay
The double relay is incorporated into the engine relay unit (depending on the version)
(27): double relay
One relay for the main engine management ECU supply and another for distribution of the power supply
Cylinder (1115) reference sensor
Camshaft side view
| reference | designation |
|---|---|
| 29 | timing gear |
| 28 | cylinder reference sensor (1115) |
| a | target (3 teeth) |
| A | top dead centre, cylinder no. 2 (compression) |
| B | top dead centre, cylinder no. 1 (compression) |
| C | top dead centre, cylinder no. 3 (compression) |
| D | top dead centre, cylinder no. 4 (compression) |
Role
The cylinder reference sensor informs the injection ECU of top dead centre in compression for each cylinder
The injection ECU requires this information in order to control the diesel injectors in sequential mode (cylinder by cylinder in the order 1-3-4-2)
NoteTo start, the engine management ECU needs the cylinder reference sensor signal and the engine speed sensor signal otherwise the engine will not start
Location
The sensor is of the Hall type, it is positioned opposite a target incorporated into the camshaft timing pinion
Knock sensor (accelerometer) (1120)
B: remote connector
(30): knock sensor
Location
The knock sensor is positioned in such a way as to receive the maximum signal for all of the cylinders
The knock sensor is positioned between the 3rd and 4th cylinders behind the engine
Role
The knock sensor is used to
- Reset the pre-injection flow in a closed loop
- Detect a diesel fuel injector jammed open
- Detect a fault linking the knock sensor to the engine management ECU
Principles of operation
The principle of operation of the knock sensor is based on detection of the combustion noises
The signal is processed to obtain a variable which quantifies the intensity of the combustion
This variable is called a "ratio"
It is the relationship between the intensity of the background noise and of the combustion noise
An initial detection window is used to set the level of the background noise
This measurement window is positioned by the engine management ECU at a time when there is no combustion
A second window is used to measure the intensity of the pre-combustion
This measurement window is placed by the engine management ECU just before the main injection
The engine management ECU monitors the reduction or increase in the "ratio" in order to adapt to the different phases of engine operation and also in order to diagnose any faults
Engine coolant temperature sensor (1220)
Role
The engine coolant temperature sensor informs the ECU about the engine coolant temperature
The role of the injection ECU in terms of the information received
- To adjust the pre-heating time
- To adjust the postheating time
- To adjust the starting flow
- Adjust the idling speed
- To authorise exhaust gas recycling (EGR)
- To adjust the fuel flow
- To limit the flow injected if the temperature of the coolant is critical (anti-boil function)
- To operate the fans
- To operate the logometer on the control panel (*)
- To operate the warning and prewarning lights (*)
(*) according to specification
Location
The engine coolant temperature sensor (31) is fitted on the engine coolant outlet housing
Fuel temperature sensor (1221)
Role
The role of the injection ECU in terms of the information received
- To adjust the fuel flow
- To calculate the fuel density
Description
| reference | designation |
|---|---|
| 32 | fuel temperature sensor |
| 33 | venturi support |
| e | fuel return to the fuel tank |
| d | diesel injector fuel return |
| c | diesel high pressure pump fuel return |
Accelerator pedal position sensor (1261)
The pedal position sensor is incorporated in the accelerator pedal
The sensor informs the engine management ECU of the accelerator pedal position
The engine management ECU thus determines the flow of diesel fuel to be injected in relation to other parameters
| reference | designation |
|---|---|
| 34 | 4 way connector |
| f | Hall effect element |
| 35 | support |
| 35 | foot throttle pedal |
| g | magnet |
Air flow meter (1310)
The air flow meter consists of two separate sensors
- The inlet air mass sensor (flow meter)
- The inlet air temperature sensor
The inlet air mass sensor (flow meter)
From this information the engine management ECU determines the following parameters
- The calculation of the rate of recirculation of the exhaust gas
- The calculation of the turbocharging pressure
- The flow to be injected to limit fumes
The inlet air temperature sensor
The inlet air temperature sensor informs the engine management ECU of the temperature of the air admitted into the engine
From this information the engine management ECU determines the following parameters
- The calculation of the theoretical volume of air
- The calculation of the injection advance
- The calculation of the injection flow
- The activation of the additional heating (at the order of the BSI)
Inlet manifold pressure sensor (1312)
Role
The sensor enables to determinate the air pressure in the intake pipe
The role of the injection ECU in terms of the information received
- Regulate the boost pressure (*)
- Regulate the HP fuel pressure
- Regulate the duration of injection (fuel flow)
(*): controlled turbocharger (injection ECU + electrovalve)
Location
(37): inlet manifold pressure sensor
Description
The sensor is of the piezo-electric type
The sensor consists of stress gauges
The pressure sensor provides a voltage proportional to the pressure of the air in the inlet pipe
Example of representation of the inlet pipe pressure sensor output signal
P = absolute pressure in Kilo pascal
V = signal voltage / 5V
Electrical special features
Allocation of channels of connector
- Terminal 1: 5 Volts
- Terminal 2: earth
- Terminal 3: signal
Engine speed sensor (1313)
The engine speed information on "DV" engine-types is provided by a new active sensor
Features of the engine speed sensor
- Located at the timing end
- Hall effect operating principle
- No adjustment or maintenance required
"h": magnetic target
(E): air gap
(38): engine speed sensor
Location
The Hall effect engine speed sensor (38) is fitted opposite a target on the oil pump body
The ferromagnetic target is fixed on the crankshaft pinion
Function
The target consists of 60 (58+2) pairs of magnetic poles distributed on the periphery of which two poles are absent to mark the top dead centre of pistons 1 to 4
NoteBy combining the two pieces of information, that from the cylinder reference sensor and that from the engine speed sensor, the engine management ECU determines the exact position of each cylinder over time
The north and south poles of the target passing in front of the sensor modify the output voltage of the sensor in terms of high status and low status
The frequency of the square signals produced by the passing of the poles of the target constitutes the engine's speed of rotation
Pay attention to the following points
- Wash your hands prior to any handling of the crankshaft pinion
- Avoid any impact or damage to the magnetic track
- Use of sharp-edged tools is prohibited
- Do not approach with tools that are magnetic
- Do not bring force to bear on the target body
(1320) atmospheric pressure sensor
Role
The sensor measures the atmospheric pressure
The role of the injection ECU in terms of the information received
- To determine the air density
- To prevent recycling when driving at high altitude
NoteThe density of the air decreases according to the altitude
Description
The sensor is of the piezo-electric type
The sensor consists of stress gauges
The sensor supplies a voltage proportionate to the atmospheric pressure
Location
The atmospheric pressure sensor (39) is integrated in the injection ECU
WarningThe atmospheric pressure sensor can not be separated from the injection ECU
High pressure fuel sensor (1321)
(40): high pressure fuel sensor
(41): metal gasket
Role
The sensor provides a voltage which is proportional to the fuel pressure in the high pressure common injection rail (50 to 1500 bars)
Electrical special features
Allocation of channels of connector
- Terminal 1: pressure information (0 to 5 volts)
- Terminal 2: earth
- Terminal 3: + 5 volts supply
Redundant brake pedal switch (7308)
Role
The redundant brake pedal switch enables the injection ECU to provide good driveability
The information from the main brake switch (2100) and from the redundant brake switch is compared continuously in order to detect any faults
NoteThe redundant brake pedal switch is connected to the engine management ECU by wire
Location
The redundant brake pedal switch is installed on the pedal assembly
The redundant brake pedal switch is installed on vehicles fitted with cruise control
Clutch switch (7306)
Role
The clutch switch allows the injection ECU to perform the driven idle function
Location
The clutch switch is located on the pedal set
NoteThe clutch switch is only fitted on vehicles fitted with cruise control