Engine Control Component Description
Engine Control Component DescriptionDescription and Operation
Accelerator Pedal Position (APP) Sensor
The APP sensor is mounted on the accelerator pedal control assembly. The sensor is made up of two individual sensors within one housing. The ECM uses the APP sensors to determine the amount of acceleration or deceleration that is desired. The APP sensors are hall element type sensors. Each APP sensor provides a different signal to the ECM on the each signal circuit, which relative to the position changes of the accelerator pedal angle. The APP sensor 1 signal voltage is low at rest and increases as the pedal is depressed. The APP sensor 2 signal voltage is high at rest and decreases as the pedal is depressed.
Barometric Pressure (BARO) Sensor
The BARO sensor is installed inside of the ECM and converts the BARO into a voltage signal. The ECM uses this voltage signal to calibrate the fuel injection quantity and injection timing for altitude compensation.
Boost Pressure Sensor
The boost pressure sensor is located in the air induction tubing. The boost pressure sensor is a transducer that varies voltage according to changes in the air pressure inside the air tubing. The boost pressure sensor provides a signal to the ECM on the signal circuit, which is relative to the pressure changes in the air tubing. The ECM should detect a low signal voltage at a low boost pressure, such as low engine load. The ECM should detect high signal voltage at a high boost pressure, such as high engine load.
Camshaft Position (CMP) Sensor
The CMP sensor is installed on the cylinder head at the rear of the camshaft gear. The CMP sensor detects total of five projections per one engine cycle (four projections arranged equally every 90� and one reference projection on the camshaft gear surface). The CMP sensor is a magnetic resistance element (MRE) type sensor, which generates a square wave signal pulse.
Crankshaft Position (CKP) Sensor
The CKP sensor is located on the flywheel housing. The sensor rotor is fixed on the flywheel. There are 56 notches spaced 6� apart and a 30� section that is open span. This open span portion allows for the detection of top dead center (TDC). The CKP sensor is a magnetic resistance element (MRE) type sensor, which generates a square wave signal pulse. Detecting the open span portion from the CKP sensor and one reference projection from the camshaft position (CMP) sensor, the ECM determines cylinder #1 compression TDC to ensure they correlate with each other.
Engine Coolant Temperature (ECT) Sensor
The ECT sensor is installed to the thermostat housing. The ECT sensor is a variable resistor and it measures the temperature of the engine coolant. When the ECT sensor is cold, the sensor resistance is high. When the engine coolant temperature increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the signal circuit.
Fuel Temperature (FT) Sensor
The FT sensor is installed to the fuel supply pump. The FT sensor is a variable resistor and it measures the temperature of the fuel entering the fuel supply pump. When the FT sensor is cold, the sensor resistance is high. When the fuel temperature increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the signal circuit.
Intake Air Temperature (IAT) Sensor 1
The IAT sensor 1 is fitted between the air cleaner and turbocharger. It is internal to the mass air flow (MAF) sensor. The IAT sensor 1 is a variable resistor and it measures the temperature of the air entering the engine. When the IAT sensor 1 is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a high voltage on the signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the signal circuit.
Mass Air Flow (MAF) Sensor
The MAF sensor is an air flow meter that measures the amount of air that enters the engine. It is fitted between the air cleaner and turbocharger. A small quantity of air that enters the engine indicates deceleration or idle speed. A large quantity of air that enters the engine indicates acceleration or a high load condition. The MAF sensor assembly consists of a MAF sensor element and an intake air temperature (IAT) sensor 1 that are both exposed to the air flow to be measured. The MAF sensor element measures the partial air mass through a measurement duct on the sensor housing.