D Group 28 Design and Function Sensors Ambient Air Temperature Sensor The Ambient Air Temperature Sensor is used to detect the outside air temperature. The sensor modifies a voltage signal from the ECM. The modified signal returns to the ECM as the ambient air temperature. The sensor uses a thermistor that is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases. The Ambient Air Temperature Sensor is located in the front of the vehicle. Ambient (Atmospheric) Pressure Sensor The Ambient (Atmospheric) Pressure Sensor contains a pressure sensitive diaphragm and an electrical amplifier.
Mechanical pressure applied to the diaphragm causes the diaphragm to deflect and the amplifier to produce an electrical signal proportional to the deflection. The Ambient (Atmospheric) Pressure Sensor is built into the Engine Management System (EMS) Module. Camshaft Position Sensor The Camshaft Position (Engine Position) Sensor is located in the rear face of the timing gear cover at the rear of the engine, near the bottom of the valve cover. It uses magnetic induction to generate a pulsed electrical signal. It senses the passage of seven (7) timing bumps on the edge of the camshaft dampener.
Six of the holes correspond to the phasing of the electronic unit injectors, while the seventh hole indicates the top dead center position. Cooling Fan Speed (CFS) Sensor On engines with an electronically controlled viscous fan drive, the electronic fan drive contains a Hall effect speed sensor. When the engine is running, a series of vanes in the fan drive housing rotates past a magnet in the fan drive solenoid generating a pulsed voltage signal.
The Engine Management System (EMS) Module monitors the status if the air conditioning system and signals from the Engine Coolant Temperature (ECT) Sensor, the Engine Oil Temperature (EOT) Sensor, and the Engine Speed/Timing (RPM/TDC) Sensor and calculates the optimal cooling fan speed. The Cooling Fan Speed Sensor is located in the fan drive on the front of the engine. 3