Design [3 of 4]

Fuel pressure sensor / fuel temperature sensor




The fuel pressure sensor is combined and consisted of both the fuel pressure sensor and the fuel temperature sensor. The sensor detects the fuel pressure (the absolute pressure) and the temperature of the fuel in the fuel rail.
The fuel pressure sensor is on the right-hand end of the fuel rail.

Fuel pressure sensor
The pressure sensor is a piezo resistive type resistor, the resistance of which changes with the pressure. Depending on the pressure in the fuel rail, an analog signal of 0-5 V is transmitted. Low pressure results in low voltage, high pressure in high voltage.
The engine control module (ECM) then uses this signal to adjust the pressure in the fuel rail using the fuel pump control module. See also: Function Function
The pressure sensor is supplied with 5 V and grounded in the engine control module (ECM). The pressure sensor transmits a signal indicating the fuel pressure to the engine control module (ECM) on a separate cable.
The engine control module (ECM) can diagnose the fuel pressure sensor. Its signals (pressure and temperature) can be read using VIDA.

Note! The absolute pressure is displayed when using VIDA parameter readout to read off the fuel pressure. If there is no pressure at the fuel rail, the atmospheric pressure will be displayed.

Hint: The relative pressure (absolute pressure minus atmospheric pressure) is displayed when reading off the fuel pressure via a manometer connected to the fuel rail.

Fuel temperature sensor
The temperature sensor is an NTC sensor. The sensor is supplied with voltage (signal) from and grounded in the engine control module (ECM).
The resistance in the sensor changes according to the temperature of the fuel. This provides the engine control module (ECM) with a signal of between 0-5 V. Low temperature results in high voltage (high resistance). High temperature results in low voltage (low resistance).
The engine control module (ECM) uses the signal to calculate fuel density.

Camshaft position (CMP) sensor




The function of the camshaft position (CMP) sensor is to detect the flanks of the camshaft rotor. The signal from the sensor is used by the engine control module (ECM) to determine the angle of the camshaft.
Each camshaft has four segments per camshaft revolution. A pulse wheel on the camshaft consisting of four teeth (the teeth are positioned by each flank) is used by the camshaft position sensor (CMP) to detect the segments.
The teeth on the camshaft gear wheel are not equally wide. This allows the control module to determine which flank is detected and therefore which operating cycle the camshaft is in.
When the operating cycle of the camshaft is established, the control module is able to determine which cylinder should be ignited. In the event of misfire or knock in the engine, the control module is also able to determine which cylinder is misfiring or knocking. See also: Knock sensor (KS) and Engine speed (RPM) sensor
Data about the position of the camshaft is used during camshaft control (CVVT). See also: Function Function
The sensor, which is a magnetic resistor with a permanent magnet, is grounded in the control module and supplied with 5 V from the control module. When one of the teeth on the camshaft pulse wheel passes the camshaft position (CMP) sensor, a signal is transmitted to the control module from the camshaft position (CMP) sensor. The signal varies between 0-5 V and is high when a tooth is in contact with the camshaft position (CMP) sensor and low when the tooth leaves the camshaft position (CMP) sensor.
The camshaft position (CMP) sensor is positioned at the rear of the engine by the controllable camshaft (CVVT).
The engine control module (ECM) can diagnose the camshaft position (CMP) sensor.

Knock sensor (KS)




The function of the knock sensor (KS) is to monitor combustion knocking from the engine. Knocking may damage the engine and reduces the efficiency of engine combustion.
If the engine control module (ECM) registers knocking from any of the cylinders, the ignition will be retarded for that cylinder at the next combustion stage. If repeated ignition retardation does not prevent knocking, the injection period will be increased. This has a cooling effect. On turbocharged engines the boost pressure will also be lowered, reducing the engine load.
The sensor is made up of a piezo electrical crystal. If there is engine knock, vibrations (sound waves) spread through the cylinder block to the knock sensor (KS). The resultant mechanical stress in the piezo electrical material in the knock sensors generates a voltage. This signal is transmitted to the Engine Control Module (ECM). The signal corresponds to the frequency and amplitude of the sound waves. This allows the Engine Control Module (ECM) to determine if the engine is knocking. The camshaft position (CMP) sensor and engine speed (RPM) sensor are used to determine the operating cycle of the engine (which cylinder is igniting) and therefore which cylinder is knocking.
The knock sensors (KS) are positioned on the cylinder block below the intake manifold.
Ignition retardation due to knocking can be read using VIDA.
The engine control module (ECM) can diagnose the knock sensors (KS).

Electronic throttle unit




The electronic throttle unit, using the control signal from the engine control module (ECM), regulates the amount of air for engine combustion. This is done using an electronic shutter.
The electronic throttle unit consists of a round throttle disc on a shaft. This is turned using a DC motor (damper motor), gear wheel and two springs, an opening spring and a return spring. The damper motor is controlled by the control module and is supplied with powered by a built in power stage in the control module. At one of the limit positions the throttle disc is closed so that no air can pass the throttle unit. At the other limit position the throttle disc is parallel to the air flow so that the air is able to freely pass through the throttle unit. The throttle disc shaft is mechanically connected to two built-in potentiometers (position sensors) which are supplied with power by the control module. The signals from the potentiometers provide the control module with data about the position of the throttle disc. The throttle unit also has a connector with six gold plated terminal pins.

Note! A damaged pin surface can interfere with the function.

1. Current channels, potentiometers
2. Contact strips, potentiometers
3. Spring
4. Spring
5. Throttle disc
6. Damper motor
7. Gear wheel
8. Gear sector
9. Connector
The throttle unit is located on the engine intake manifold.
In the event of a fault, the throttle unit must be replaced as a single unit.
The engine control module (ECM) can diagnose the electronic throttle unit.

Throttle position (TP) sensor
See Electronic throttle unit

Accelerator pedal (AP) position sensor




The function of the accelerator pedal (AP) position sensor is to provide the engine control module (ECM) and central electronic module (CEM) with information about the position of the accelerator pedal. This data is used by the engine control module (ECM) to deploy the shutter in the throttle unit to the correct angle.
The sensor consists of a plastic housing with two potentiometers, an AC/DC converter and circuits. The potentiometers are connected to a shaft which is affected by the position of the accelerator pedal (AP). The resistance in the potentiometers changes with the position of the accelerator pedal (AP).
The accelerator pedal (AP) position sensor transmits an analog and a digital signal (pulse width modulated (PWM) signal). The signals give information about the position of the accelerator pedal (AP). The digital signal is generated by the AC/DC converter in the sensor and is transmitted to the engine control module (ECM). The analog signal is transmitted central electronic module (CEM) and on to the engine control module (ECM) via the controller area network (CAN). The analog and digital signals are used at the same time by the engine control module (ECM) to regulate the throttle shutter angle.
The sensor is supplied with 12 V by the system relay via a fuse and is grounded in the car body.
The digital signal is also used in conjunction with the analog signal for accelerator pedal (AP) position sensor diagnostics. The accelerator pedal (AP) position sensor signals can be read off using VIDA. A diagnostic trouble code (DTC) is stored if the engine control module (ECM) detects a difference between the analog and digital signals. The engine control module (ECM) then uses a minimal value to ensure the function (limp home).
The accelerator pedal (AP) position sensor is located on the accelerator pedal bracket.

Clutch pedal switch




Engine control module (ECM) receives information about the clutch pedal's position in two ways.
Partly from a clutch pedal position sensor which is directly connected to Central electronic module (CEM), and partly from a clutch pedal switch directly connected to the Engine control module (ECM).
The function of the clutch pedal switch is to provide extra safety for the function autostart. In order for the function to be activated, the Engine control module (ECM) must receive signal that indicates pressed down pedal from the clutch pedal switch.
To start without the function autostart it is enough that any of the signals (from clutch pedal position sensor or clutch pedal switch) indicates pressed down pedal.
For more information about the clutch pedal position sensor, see Design and Function, central electronic module (CEM).
In its starting position, the clutch pedal switch is open (clutch pedal released). The switch's installation shall be adjusted so that is is closed when the clutch pedal passes 75% of full pedal movement.
The clutch pedal switch is on the pedal box by the clutch pedal.
The engine control module (ECM) can diagnose the clutch pedal switch. The status (position) of the switch can be read using the diagnostic tool.