Ford Workshop Service and Repair Manuals

Components

IAT sensor

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.

CMP sensor

The CMP sensor uses the Hall effect principle and is supplied with a reference voltage of 5 volts.

During starting, the CKP sensor and the CMP sensor are synchronized. If both signals are present, the engine will 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.

EOP sensor

The EOP sensor is located in the cylinder head. The EOP is connected to the instrument cluster and is not directly part of the electronic engine control system. The EOP sensor registers engine oil pressure. The sensor opens when a defined oil pressure is reached and the engine oil pressure warning light is illuminated on the instrument cluster.

MAF sensor

The MAF sensor measures the mass of air entering the intake system, the measurement being based on the constant temperature hot wire principle. Suspended in a bypass duct are a hot wire probe and an air temperature probe. The PCM makes sure that the hot wire probe is always 200ºC hotter than the air temperature probe. The hot wire probe is cooled by the air flowing through the intake system and the PCM varies the heating current to maintain the 200ºC temperature difference. The change in heating current is measured as a voltage drop across a precision resistor and is assigned to a corresponding mass air flow calculation by the PCM.

PCM

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).

FRP sensor

The FRP sensor is located in the fuel rail and measures the fuel pressure within the fuel system.

The fuel pressure 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.

Fuel pressure regulator

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.

KS

In conjunction with the PCM, the KS monitors the combustion process and regulates the injection period so that predetermined volumes of fuel are injected into the cylinders at every operating cycle.

By constantly measuring the amount of knock present and adjusting the injection period, the emission values of the engine remain stable.

CKP sensor

The CKP sensor is an inductive pulse generator which scans 36-1 cast protrusions on the flywheel. Minus one means that one of the cast protrusions is missing and this gap is located at 90 degrees before top dead centre. This gap is used by the PCM as a reference for crankshaft position.

The CKP sensor uses the Hall effect principle.

CHT sensor

The CHT sensor is screwed directly into the cylinder head and measures the temperature of the material of the cylinder head, rather than the coolant temperature. This is a more accurate measurement of the engine temperature and the information is used by the instrument cluster for the temperature gauge indication. It is also used by the PCM to calculate fuel injection timing and period of injection which will vary dependant on the engine temperature.

Fuel metering valve

The fuel metering valve adjusts the quantity of fuel to the high-pressure pump elements as a function of engine operating conditions. This improves engine efficiency.

The fuel metering valve is controlled by the PCM using pulse-width modulation.

The fuel metering valve is closed when de-energized.

Fuel temperature sensor

The fuel temperature sensor is designed as a resistor with a negative temperature coefficient (NTC).

The fuel temperature sensor monitors the temperature of the fuel returning to the fuel tank from the fuel pump and the fuel injectors and sends a signal to the PCM.

The signal is required by the PCM for making fine adjustments to the fuel injection timing and the fuel injection quantity.

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 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.