Injection double relay (engine relay unit)
(1) injection double relay
The double injection relay is integrated in the engine servo unit (BSM)
The first relay of the double injection relay supplies the following components
- The injection ECU
- The oxygen sensors
The second relay of the double injection relay supplies the following components
- The fuel pump (low pressure)
- The injection ECU (power part)
The airbag control units incorporate the function for interrupting the supply of the fuel pump (discontinuation of the inertia switch)
The 2 relays of the double injection relay are controlled by the injection ECU
The engine fuse box can cut off the supply to the second relay in the event of an impact
If a pyrotechnic component is deployed, the fuel supply is cut off (cutting of the supply from the second relay of the double injection relay)
When restarting the vehicle
- Switch off the ignition
- Switch on the ignition (ignition switched +)
NoteAfter switching off the ignition, the double injection relay remains energised for 10 seconds or for 6 minutes in the event of post-ventilation
Engine speed sensor (1313)
Role
The engine speed sensor is located facing the teeth of the engine flywheel
The role of the injection ECU in terms of the information received
- Checking the engine speed
- Determining the position of the crankshaft
- Calculation of the ignition advance
- Adjustment of idling speed
Description
The engine speed sensor is of the inductive type
Constitution of the engine speed sensor
- A permanent magnet
- An electric winding
The engine speed sensor generates an electrical signal each time the engine flywheel tooth passes by (change in magnetic field)
The 58 teeth are used to work out the engine speed
The 2 missing teeth are used to work out the crankshaft position (no signal)
NoteThe air gap value is not adjustable
Electrical features
Allocation of channels of connector
- Terminal 1: signal
- Terminal 2: earth
- Terminal 3: screening (according to model)
Resistance between channels 1 and 2: 425 to 525 ohms
Characteristics of the signals emitted: variable frequency alternating voltage
Location
Location: on the clutch housing
Accelerator pedal sensor (1261)
Role
Role of the accelerator pedal sensor
- Records the driver's request (acceleration, decelaration)
- Sends information to injection ECU
The role of the injection ECU in terms of the information received
- To determine the opening of the motorised butterfly
- To determine the injection time
- To determine the ignition advance
Description
(2) tight spot sensor
The accelerator pedal sensor provides 2 signals (voltage)
The voltage value of one signal is equivalent to half of the other one
Items of information from the connector channels are constantly compared with each other to detect a possible fault
NoteThe accelerator pedal sensor does not have a contact
Allocation of channels of connector
- Terminal 1: output signal 1
- Terminal 2: earth
- Terminal 3: output signal 2
- Terminal 4: 5 Volts
- Terminal 5: accelerator pedal point of resistance signal (vehicle equipped with the speed limiting function)
Accelerator pedal released
- Voltage between earth and track 1: 0,3 to 0,6 volt
- Voltage between earth and track 2: 0,15 to 0,3 volt
Accelerator pedal pressed fully down
- Voltage between earth and track 1: 3,5 to 4 Volts
- Voltage between earth and track 2: 1,75 to 2 Volts
Engine coolant temperature sensor (1220)
Role
The engine coolant temperature sensor informs the ECU of the temperature of the engine coolant fluid
The role of the injection ECU in terms of the information received
- To adjust the starting flow
- Adjust the idling speed
- To obtain an accelerated idle speed which decreases as the engine heats up
Description
The engine coolant temperature sensor consists of a Negative Temperature Coefficient (NTC) resistance
The more the temperature increases, the more its resistance value is reduced
Electrical features
Supply: injection ECU
Allocation of channels of connector
- Terminal 1: engine coolant temperature signal
- Terminal 2: earth
Air temperature sensor (1310)
Role
The air temperature sensor informs the ECU of the temperature of the air admitted
The role of the injection ECU in terms of the information received
- Calculate the density of the ambient air
- Determine the quantity of fuel to be injected
Description
The air temperature sensor consists of a Negative Temperature Coefficient (NTC) resistance
The more the temperature increases, the more its resistance value is reduced
Knock sensor (1120)
Role
The engine knock information, transmitted by the sensor, enables the ECU to correct the ignition advance (reduction)
Knock is a vibratory phenomenon due to an exploding combustion of the air/fuel mixture in one of the 4 cylinders
The pinking sensor transmits the peaks in voltage to the injection computer in the event of "pinking"
After engine knocking information, the ECU reduces the ignition timing, and simultaneously enriches the air-fuel mixture
Electrical features
Supply: injection ECU
Allocation of channels of connector
- Terminal 1: + signal
- Terminal 2: earth
Location
Location: cylinder block
Upstream oxygen sensor (1350)
Role
The hydrocarbons modify the reference air inside the upstream oxygen sensor and thus the richness signal
The role of the injection ECU in terms of the information received
- To determine the fuel / air mixture (richness)
- Mixture regulation
Description
The upstream oxygen sensor delivers virtually permanent information to the ECU on the air-petrol dosage
The "rich" or "lean" mixture information is given by 0 to 1 V voltages
- Lean mixture: 0,1V
- Rich mixture: 0,9V
A heating device placed inside the sensor enables it to rapidly reach its operating temperature (+ 300°C)
Electrical features
The upstream oxygen sensor is equipped with 4 -way caliper connector
Allocation of channels of connector
- Terminal 1: + 12 volts supply (oxygen sensor heater)
- Terminal 2: earth
- Terminal 3: + signal
- Terminal 4: - signal
Location
The upstream oxygen sensor is positioned on the exhaust between the engine and the catalytic converter
Downstream oxygen sensor (1351)
Role
The downstream oxygen sensor controls the operation of the catalytic converter
Description
The downstream oxygen sensor has the same characteristics as the upstream oxygen sensor
Location
The downstream oxygen sensor is positioned at the outlet of the catalytic converter
Power steering pressure switch (7001) (dual VAN/CAN vehicle not 1007)
Role
The power steering pressure switch enables the engine ECU to increase the engine idling speed during a parking manoeuvre
Conditions for increasing the idling speed
- Vehicle speed lower than 4 kph
- Pressure switch activated (power-assisted steering)
Location
On the union between the power assisted steering valve and pump
(1320) injection ECU
Role
The injection ECU controls the injection based on the engine torque information
- The injection ECU calculates the need for engine torque based on information from the accelerator pedal sensor
- The engine torque request takes account of a number of corrections (torque absorbed by the alternator, torque absorbed by the air con compressor etc.)
- The engine torque request is converted into injection timing, injection phasing, butterfly opening, and ignition advance
The injection ECU controls the ignition and injection as a function of the different parameters received
These parameters are
- The engine speed and the crankshaft position
- The inlet air pressure (pressure sensor)
- The position of the accelerator pedal
- The engine temperature (coolant thermistor)
- The temperature of the air drawn into the cylinders (air temperature sensor)
- The engine coolant temperature
- The torque absorbed by the alternator
- The torque absorbed by the air conditioning compressor (calculation)
- The speed of the vehicle (vehicle speed sensor; speed information provided by the ESP ECU)
- The oxygen content of exhaust gases (upstream oxygen sensor)
- The pinking (knock sensor)
- The air conditioning demand
- The battery voltage
- The pressure in the power assisted steering circuit
Using this information, the injection ECU controls
- The opening of the butterfly housing
- The idling speed regulation
- The ignition advance and the coil charging time
- The amount of fuel injected, proportional to the injector opening time
- The fuel vapour recycling (canister bleed electrovalve)
- The injection cut-off on overspeed and deceleration
- The air conditioning cut-off
- The oxygen sensor heating element (downstream oxygen sensor, upstream oxygen sensor)
The injection ECU also controls the following functions
- Emergency strategies
- The diagnostic with memorisation of failures
- The regulation of vehicle speed
- Reduction of engine torque during an activation of the ESP
- The engine cooling
- The cooling requirement for the air conditioning (BRAC)
- The electronic immobiliser
- The dialogue with other ECUs (BSI, ABS,...) via the CAN (*)
(*) CAN = Controller Area Network
The injection ECU software is updated by downloading (ECU fitted with a flash EPROM)
Allocation of channels of connector
| channel number | matching the tracks |
|---|---|
| A1 | (not used) |
| A2 | piloted alternator charge information |
| A3 | input: engine coolant temperature sensor signal + |
| A4 | engine coolant temperature sensor earth |
| B1 | (not used) |
| B2 | knock sensor masking earth |
| B3 | knock sensor signal + |
| B4 | knock sensor signal - |
| C1 | supply of the motorised butterfly position sensor (5 volts) |
| C2 | motorised butterfly 2 position sensor signal |
| C3 | motorised butterfly 1 position sensor signal |
| C4 | earth on the motorised butterfly position sensor |
| D1 | output: supply of the inlet air pressure sensor (5 volts) |
| D2 | input: intake air temperature signal |
| D3 | input: inlet air pressure sensor signal |
| D4 | inlet air pressure sensor earth |
| E1 | (not used) |
| E2 | (not used) |
| E3 | input: DEPHIA signal |
| E4 | signal earth DEPHIA |
| F1 | input: oil pressure switch |
| F2 | power steering at limit (206 and PARTNER) |
| F3 | (not used) |
| F4 | output: canister discharge electrovalve control |
| G1 | output: butterfly motor control (-) |
| G2 | output: butterfly motor control (+) |
| G3 | (not used) |
| G4 | (not used) |
| H1 | (not used) |
| H2 | (not used) |
| H3 | (not used) |
| H4 | (not used) |
| channel number | matching the tracks |
|---|---|
| A1 | (not used) |
| A3 | signal from the engine speed sensor - |
| A4 | input: signal from the engine speed sensor + |
| B1 | (not used) |
| B2 | (not used) |
| B3 | (not used) |
| B4 | (not used) |
| C1 | catalytic converter downstream lambda sensor earth |
| C2 | catalytic converter downstream lambda sensor + |
| C3 | (not used) |
| C4 | (not used) |
| D1 | catalytic converter upstream oxygen sensor earth |
| D2 | oxygen sensor upstream of the catalytic converter + |
| D3 | (not used) |
| D4 | (not used) |
| E1 | engine oil temperature and level sensor earth |
| E2 | input: engine oil level sensor |
| E3 | oil temperature sensor connection |
| E4 | piloted thermostat control |
| F1 | cylinder injector control N°1 |
| F2 | cylinder injector control N°2 |
| F3 | cylinder injector control N°3 |
| F4 | cylinder injector control N°4 |
| G1 | (not used) |
| G2 | (not used) |
| G3 | output: command for heating of the catalytic converter downstream lambda sensor |
| G4 | output: command for heating of the catalytic converter upstream lambda sensor |
| H1 | (not used) |
| H2 | (not used) |
| H3 | "double computer-coil" ignition: cylinders Nos. 1 and 4 |
| H4 | "double computer-coil" ignition: cylinders Nos. 2 and 3 |
| channel number | matching the tracks |
|---|---|
| A1 | CAN IS LOW |
| A2 | CAN IS HIGH |
| A3 | input: power relay control |
| A4 | (not used) |
| B1 | line K |
| B2 | input: action on the clutch pedal |
| B3 | output: hands-free starting control |
| B4 | (not used) |
| C1 | (not used) |
| C2 | alternator charge information |
| C3 | input: cooling fan status |
| C4 | (not used) |
| D1 | (not used) |
| D2 | (not used) |
| D3 | (not used) |
| D4 | output: fan unit 1 control |
| E1 | earth of the tight spot sensor of the accelerator pedal |
| E2 | accelerator pedal position tight spot signal (+) |
| E3 | (not used) |
| E4 | output: fan unit 2 control |
| F1 | earth of the accelerator pedal position sensor |
| F2 | input: accelerator pedal position sensor signal n° 1 |
| F3 | engine running output |
| F4 | input: main relay control |
| G1 | output: supply of the accelerator pedal position sensor (5 Volts) |
| G2 | input: accelerator pedal position sensor signal n° 2 |
| G3 | input: additional brake pedal switch information |
| G4 | (not used) |
| H1 | refrigerant pressure sensor earth |
| H2 | input: refrigerant pressure sensor signal |
| H3 | output: air conditioning pressure sensor supply (5 Volts) |
| H4 | input: vehicle speed |
| J1 | (not used) |
| J2 | (not used) |
| J3 | (not used) |
| J4 | output: canister bleed valve control |
| K1 | (not used) |
| K2 | (not used) |
| K3 | input: ignition+ |
| K4 | (not used) |
| L1 | body earth |
| L2 | body earth |
| L3 | (not used) |
| L4 | input: injection ECU supply |
| M1 | body earth |
| M2 | input: supply by engine relay unit (BSM) power relay |
| M3 | input: supply by engine relay unit (BSM) power relay |
| M4 | input: supply by engine relay unit (BSM) power relay |