The IAT sensor is a temperature dependent resistor which has a negative temperature coefficient, therefore its temperature changes inversely with respect to ambient temperature. The IAT sensor is supplied with a reference voltage by the PCM. When the intake air changes temperature, the resistance of the IAT sensor changes therefore changing the output voltage. The output voltage is assigned to a corresponding intake air temperature by the PCM.
The signal from the IAT sensor is used as a correction variable for calculating the fuel injection quantity.
MAF sensor
The PCM is attached to the windshield washer reservoir and has 3 electrical connectors with a total of 128 pins.
The PCM monitors and processes the signals from the sensors. The fuel injectors, the fuel metering valve and the fuel pressure regulator are also controlled by the PCM.
The PCM can be diagnosed through the data link connector (DLC) using the Worldwide Diagnostic System (WDS).
CMP sensor
The CMP sensor uses the Hall effect principle and is supplied with a reference voltage of 5 V.
During starting, the CKP sensor and the CMP sensor are synchronized. If both signals are present, the engine can be started.
If the signal from the CMP sensor fails while the engine is running, the engine continues to run using the signals from the CKP sensor.
If the CMP signal is missing at the next starting operation, it will not be possible to start the engine.
CKP sensor
The fuel pressure regulator is screwed directly onto the high-pressure outlet of the fuel pump.
The fuel pressure regulator regulates the fuel pressure at the high-pressure outlet and thereby the fuel pressure to the fuel rail.
In addition, the fuel pressure regulator dampens fuel pressure fluctuations which arise when the fuel pump is supplying fuel and as a result of the fuel injection process.
Fuel metering valve
The FRP sensor is located in the fuel rail and measures the fuel pressure within the fuel system.
The FRP sensor consists of a piezoelectric element that sends a variable voltage signal to the PCM, as a function of fuel pressure.
The PCM uses this signal to calculate how long the fuel injectors are to be actuated for and to regulate the fuel pressure by means of the fuel pressure regulator.
Brake pedal position (BPP) switch and brake light switch
The BPP switch is connected to the instrument cluster through the CAN bus.
The BPP switch is closed when de-energized and sends a ground signal to the PCM.
The brake light switch is connected with the PCM through a conventional electrical connector.
The brake light switch is open when de-energized. When the brake light switch is closed, it sends 12 volts to the PCM.
The signals of the BPP switch and the brake light switch are used if the accelerator pedal position (APP) sensor should fail.
In this instance, the PCM compares the signals of the BPP switch and brake light switch.
APP sensor
The APP sensor is a double contactless inductive sensor.
For safety reasons, the APP sensor consists of two sensors.
If the APP sensor malfunctions when the vehicle is in operation, a diagnostic trouble code (DTC) will be stored in the PCM.
If one of the sensors in the APP sensor should fail, the engine will operate at reduced power.
If the vehicle is fitted with a driver information system, the fault message "REDUCED ACCELERATION" will be displayed.
If both sensors of the APP switch fail, after a single operation of the BPP switch and the brake light switch and then after a plausibility check, the engine is controlled up to a speed of 1200 RPM. The vehicle can be accelerated to a maximum speed of 56 km/h (35 mph).
When the BPP switch and the brake light switch are actuated again, engine speed will drop to idle speed. Once the BPP switch and the brake light switch are de-energized again, engine speed is increased again.
If the vehicle is fitted with an information and message system, the fault message "REDUCED TOP SPEED" will be displayed.
If the vehicle is not fitted with an information and message system, the malfunction indicator lamp (MIL) will be illuminated to indicate a system fault.