AMBIENT (BAROMETRIC) PRESSURE SENSOR The Cooling Fan Speed Sensor is located in the fan drive on the front of the engine. The Ambient (Barometric) 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. CRANKSHAFT POSITION (ENGINE SPEED) SENSOR The Crankshaft Position (Engine Speed) Sensor uses magnetic induction to generate a pulsed electrical signal. Notches are machined into the edge of the flywheel. When one of the notches passes close to the sensor, electric pulses result.
The Ambient (Barometric) Pressure Sensor is built into the Engine Management System (EMS) Module. The Crankshaft Position (Engine Speed) Sensor also indicates when the crankshaft is at the top dead center position. The sensor recognizes the end of one of the group of 18 notches and aligns that to the top dead center mark on the Engine Position (EP) Sensor. BOOST AIR PRESSURE (BAP) SENSOR The Boost Air 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.
DPF DIFFERENTIAL PRESSURE SENSOR The function identifies and indicates malfunction of the (DPF) Diesel Particulate Filter by analyzing the pressure drop over the (DPF) Diesel Particulate Filter. This is done by making a check for deviation between sensor value and a model pressure drop. The differential pressure sensor is used to measure difference in pressure across the DPF filter. The sensor connects to tubes which connect to the DPF housing before and after the DPF filter. The sensor output is used as part of the regeneration strategy and also for system fault detection if the filter becomes overloaded. In some extreme cases the engine will derate.
The Boost Air Pressure Sensor is threaded into the top and to the rear of the intake manifold on the left side of the engine. CAMSHAFT POSITION (ENGINE 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.
The Differential Pressure DPF Sensor is located on the side of the Diesel Particulate Filter (DPF). DPF INLET THERMOCOUPLE (A1) COOLING FAN SPEED (CFS) SENSOR This thermocouple is used to measure exhaust gas temperature as it enters the DPF assembly. The DPF ECU monitors this temperature and will not allow DPF regeneration until the system is sufficiently warmed-up. 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 DPF inlet thermocouple is located on the inlet to the DPF. Page 8 DESCRIPTION AND OPERATION