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ENGINE CONTROL COMPONENTSAccelerator Pedal Position (APP) Sensor
The APP sensor is a 2-track potentiometer that is used to calculate driver demand for power based on the rotation angle of the accelerator pedal. The sensor receives a reference voltage from the powertrain control module (PCM) and provides a variable voltage signal directly proportional to the accelerator pedal position. The PCM uses the 2 APP sensor inputs to calculate the desired fuel quantity, injection timing, and the correct fuel pressure. A concern with the APP sensor illuminate the powertrain malfunction indicator (wrench). Normal engine operation is permitted if the PCM detects a concern on one of the 2 sensor signals. If the PCM detects a concern on both of the sensor signals, the PCM only allows the engine to operate at idle.
Air Filter Restriction Gauge
An air filter restriction gauge is located in the cleaner housing. When the air flow in the intake air system reaches the maximum allowable restriction limit, the air filter restriction gauge indicator moves from the yellow bar to the red bar at the base of the gauge. Correct the source of the restriction and manually reset the gauge by pressing the red button at the top of the gauge.
Ambient Air Temperature (AAT) Sensor
The AAT sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases, and the resistance increases as the temperature decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical voltage signal to the powertrain control module (PCM) corresponding to temperature.
Thermistor-type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow. Voltage that is dropped across a fixed resistor in a series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.
The AAT sensor provides ambient air temperature information to the PCM which is used for the temperature sensor correlation tests and controls the reductant heaters. The PCM also communicates the AAT information to all other modules on the controller area network (CAN).
Barometric Pressure (BARO) Sensor
The BARO sensor is variable capacitor sensor that is supplied a 5-volt reference signal by the powertrain control module (PCM) and returns a voltage signal to the PCM relative to the intake manifold pressure. The sensor voltage increases as the pressure increases. The BARO sensor is integral to the PCM.
Boost Pressure Gauge
The boost pressure gauge is controlled by the instrument panel cluster. The powertrain control module (PCM) sends a message through the controller area network (CAN) to the instrument panel cluster indicating engine boost pressure.
Brake Pedal Position (BPP) Switch
The BPP switch is sometimes referred to as the stoplamp switch. The BPP switch provides a signal to the PCM indicating the brakes are applied. The BPP switch is normally open and mounted on the brake pedal support. The BPP switch is hardwired to the PCM supplying battery positive (B+) voltage when the brake pedal is applied.
Brake Pressure Switch (BPS)
The BPS, part of the brake pedal position switch (BPP), is used for vehicle speed control deactivation. A normally closed switch supplies a ground signal to the PCM when the brake pedal is not applied. When the brake pedal is applied, the normally closed switch opens and the ground signal is removed from the PCM.
The normally closed BPS, along with the normally open BPP switch, are used for a brake rationality test within the PCM. The PCM misfire monitor profile learn function may be disabled if a brake switch concern occurs. If one or both brake pedal inputs to the PCM is not changing states as expected, a diagnostic trouble code (DTC) is set by the PCM strategy.
Camshaft Position (CMP) Sensor
The CMP sensor is a hall effect sensor used to determine the camshaft position by sensing the edges of the three lobed camshaft. The CMP sensor is mounted at the front of the engine block, above the crankshaft pulley.
The PCM calculates the CMP signal and the crankshaft position (CKP) sensor signal to determine the camshaft to crankshaft position for correct fuel injection timing during the compression stroke.
Charge Air Cooler (CAC)
The CAC is composed of an air to liquid heat exchanger mounted next to the engine on the driver side of the vehicle and the tubing used to connect the output of the turbocharger to the intake of the engine. The CAC is designed to cool the induction air which has been heated by the turbocharger. As the heated air flows through the CAC, heat is transferred to the coolant reducing the temperature of the intake air.
Charge Air Cooler Temperature (CACT) Sensor
The CACT sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases, and resistance increases as the temperature decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical voltage signals to the powertrain control module (PCM) corresponding to temperature.
The CACT sensor is located in the tube between the charge air cooler (CAC) and the intake throttle assembly. The sensor provides a charge air cooler output temperature signal to the powertrain control module (PCM). the PCM uses the CACT signal as an input to control the turbocharger, exhaust recirculation (EGR) valve, fuel system and the regeneration function.
Cooling Fan
The cooling fan and viscous drive actuator valve controls the fluid flow from the reservoir into the working chamber. Once viscous fluid is in the working chamber, shearing of the fluid results in fan rotation. The valve is activated by a pulse width modulation (PWM) output signal from the powertrain control module (PCM). By opening and closing the fluid port valve, the PCM controls the fan speed. Fan speed is measured through a Hall effect sensor, and is monitored by the PCM during closed loop operation. The PCM optimizes fan speed based on engine coolant temperature, the engine oil temperature, the fuel rail temperature, the transmission fluid temperature, the intake air temperature, or air conditioning requirements. When an increased demand for fan speed is requested for vehicle cooling, the PCM monitors the fan speed through the Hall effect sensor. If a fan speed increase is required, the PCM outputs the PWM signal to the fluid port, providing the required fan speed increase. During the key on, engine running (KOER) self-test, the PCM commands a 100% duty cycle. A DTC sets if the PCM detects the voltage on the valve control circuit is not within the expected range or if the fan speed is less than a calibrated value.
Crankcase Ventilation
The crankcase ventilation provides a means of routing and separating the oil from the crankcase vapors. For additional information, refer to Crankcase Ventilation System.
Crankshaft Position (CKP) Sensor
The CKP sensor is a hall effect sensor mounted at the rear of the engine block, adjacent to a pulse wheel located on the crankshaft. The pulse wheel is 60 minus 2 steel disk with 58 evenly spaced magnetic indicators and a minus 2 indicator slot spaced for each 6 degrees of crank angle. As the crankshaft rotates, the CKP sensor produces a sine wave for each magnetic indicator edge of the pulse wheel and it detects the missing 59th and 60th magnetic indicator. This configuration allows the CKP sensor to provide the powertrain control module (PCM) with the angular position of crankshaft relative to a fixed reference for the CKP sensor. The PCM uses the CKP sensor input to calculate engine RPM, fuel timing, fuel quantity, and duration of the fuel injection.
Diesel Particulate Filter
The diesel particulate filter collects the soot and ash particles that are present in the exhaust gas of diesel engines. The diesel particulate filter assembly typically consists of active precious metals deposited on a substrate filter. The exhaust gas is forced to flow through the walls of the porous substrate and exit through the adjoining channels. The particulates that are larger than the pore size of the walls are trapped for regeneration. During regeneration the temperature in the diesel particulate filter increases to greater than 550°C (1,022°F). The precious metal washcoat promotes the regeneration of the trapped particulates through the heat-generating reaction and catalyzes the untreated exhaust gas. The substrate filter is held in the metal shell by a ceramic fiber support system. The support system makes up the size differences that occur due to thermal expansion and maintains a uniform holding force on the substrate filter.
Diesel Particulate Filter Pressure Sensor
The diesel particulate filter pressure sensor is an input to the PCM and measures the pressure before the diesel particulate filter. The sensor is a differential-type sensor that is referenced to atmospheric pressure and is located at the exhaust system downstream of the diesel particulate filter. At key ON, engine OFF the diesel particulate filter pressure sensor pressure value reads 0 kPa (0 psi). The range of the sensor is 0-80 kPa (0-11.6 psi). The PCM calculates soot load based on the diesel particulate filter pressure and initiates a regeneration when the soot load reaches a threshold.
Engine Coolant Temperature (ECT) Sensor
The ECT sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases, and the resistance increases as the temperature decreases. The varying resistance changes the voltage drop across the sensor terminals and provides electrical signals to the powertrain control module (PCM) corresponding to temperature.
The ECT sensor is located on the upper coolant inlet housing. The ECT sensor measures the temperature of the engine coolant and provides a feedback signal to the PCM. The PCM uses the ECT sensor input fuel and cooling fan control.
Engine Oil Temperature (EOT) Sensor
The EOT sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases and the resistance increases as the temperature decreases. The varying resistance changes the voltage drop across the sensor terminals and provides electrical signals to the powertrain control module (PCM) corresponding to temperature.
The EOT sensor is located at the rear of the engine on the oil filter adapter. The EOT sensor measures the temperature of the engine coolant and provides a feedback signal to the PCM. The PCM uses the EOT sensor input to calculate fuel quantity and injection timing.
At low ambient air temperatures and an oil temperature of less than 70°C (158°F), low idle is increased to maintain stable idle quality. Fuel quantity and timing is controlled throughout the total operating range to provide adequate torque and power.
Exhaust Gas Recirculation (EGR) Cooler
The EGR cooler removes heat from the exhaust gases before the gases enter the intake manifold. The EGR cooler is located above the right hand valve cover. When the exhaust gases are directed through the EGR cooler, coolant from the secondary cooling system reduces the exhaust gas temperature. the exhaust gases are directed through the EGR cooler by a PCM controlled EGR cooler bypass valve.
Exhaust Gas Recirculation (EGR) Cooler Bypass Valve
The exhaust gases are directed through an EGR cooler by the EGR cooler bypass valve to remove heat before entering the intake manifold. The EGR cooler bypass valve is internal to the EGR cooler and mounted to the right hand valve cover, below the EGR valve.
When the EGR cooler bypass valve solenoid is commanded to 0% duty cycle by the powertrain control module (PCM), the EGR cooler bypass valve is closed. When the EGR cooler bypass valve is closed, the exhaust gases pass through the EGR cooler to the intake manifold.
When the EGR cooler bypass valve solenoid is commanded to 100% duty cycle by the PCM, the EGR cooler bypass valve is opened. When the EGR cooler bypass valve is open, the exhaust gases pass directly to the intake manifold without passing through the EGR cooler.
Exhaust Gas Recirculation (EGR) Cooler Bypass Valve Solenoid
The EGR cooler bypass valve solenoid is a PCM controlled vacuum solenoid. The EGR cooler bypass valve solenoid controls the EGR cooler bypass valve position by applying vacuum from the vacuum pump to the EGR cooler bypass valve actuator. The EGR cooler bypass valve solenoid is located at the top front of the EGR cooler.
When the EGR cooler bypass valve solenoid is commanded to 0% duty cycle by the powertrain control module (PCM), no vacuum from the vacuum pump is applied to the EGR cooler bypass valve actuator and the EGR cooler bypass valve is closed. When the EGR cooler bypass valve is closed, the exhaust gases pass through the EGR cooler to the intake manifold.
When the EGR cooler bypass valve solenoid is commanded to 100% duty cycle by the PCM, vacuum from the vacuum pump is applied to the EGR cooler bypass valve actuator and the EGR cooler bypass valve is opened. When the EGR cooler bypass valve is open, the exhaust gases pass directly to the intake manifold without passing through the EGR cooler.
Exhaust Gas Recirculation Temperature (EGRT) Sensor
The EGRT sensor is a thermistor type sensor. The EGRT sensor is an input to the powertrain control module (PCM) and monitors the exhaust gas temperature after the EGR cooler. The electrical resistance of the sensor increases as the temperature decreases, and the resistance decreases as the temperature increases. The varying resistance changes the voltage drop across the sensor terminals and provides electrical voltage to the PCM corresponding to temperature.
The EGRT sensor is used to determine if the EGR cooler is operating correctly.
Exhaust Gas Recirculation (EGR) Valve
The EGR valve is a variable position valve that controls the amount of exhaust that enters the intake manifold. The powertrain control valve (PCM) controls the EGR valve which operates between 0 and 1OO% duty cycles.
The EGR valve operation can be monitored by viewing the EGRVP PID which displays the EGR valve position. The EGR valve position sensor is integral the EGR valve.
Exhaust Gas Temperature (EGT) Sensor
The EGT sensor is a resistance temperature detector (RTD) type sensor. The EGT sensor is an input to the PCM and measures the temperature of the exhaust gas passing through the exhaust system. The electrical resistance of the sensor increases as the temperature increases, and resistance decreases as the temperature decreases. The varying resistance changes the voltage drop across the sensor terminals and provides electrical signals to the PCM corresponding to temperature.
The PCM uses the input from 4 EGT sensors to monitor the exhaust gas temperature. For wide frame applications, the EGT sensors are placed in the following order:
- Before the oxidation catalytic converter (DC) (EGT11)
- Between the DC and selective catalytic reduction (SCR) catalyst (EGT12)
- Between the SCR catalyst and diesel particulate filter (EGT13)
- After the diesel particulate filter (EGT14)
For narrow frame applications, the EGT sensors are placed in the following order:
- Before the DC (EGT11)
- Between the DC and diesel particulate filter (EGT12)
- Between the diesel particulate filter and SCR catalyst (EGT14)
- After the SCR catalyst (EGT13)
Exhaust Pressure (EP) Sensor
The EP sensor is a 3-wire variable capacitance sensor that is supplied a 5.0 volt reference signal by the powertrain control module (PCM) and returns a linear analog voltage signal that indicates pressure. The sensor voltage input to the PCM increases as the pressure increases.
The EP sensor measures the pressure in the exhaust manifold. The EP sensor signal is used for pressure correlation with the manifold absolute pressure (MAP) sensor and input for exhaust gas recirculation (EGR) valve control.
The EP sensor is located at the left rear of the engine. It is attached to an extension tube from the right hand up pipe going to the turbocharger.
Fan Speed Sensor (FSS)
The FSS is a Hall effect sensor integral to the cooling fan clutch. The powertrain control module (PCM) monitors the sensor input and controls the cooling fan speed based upon the engine coolant temperature, the transmission fluid temperature, and the intake air temperature requirements. When an increase in cooling fan speed for vehicle cooling is requested, the PCM monitors the FSS signal and outputs the required pulse width modulation (PWM) signal to a fluid port valve within the cooling fan.
Fuel Conditioning Module
The internal components of the fuel conditioning module include the following:
- electric fuel pump
- 10 micron fuel filter and water separator
- water in fuel (WIF) sensor
- recirculation thermostat
The electric fuel pump draws fuel from the fuel tank through the fuel supply line. When the fuel enters the fuel conditioning module, water is separated from the fuel before it flows through the 10 micron fuel filter which separates particles from the fuel. The separated water collects at the bottom of the pump. If enough water is collected, the WIF sensor detects it and the PCM illuminates the WIF indicator. The conditioned fuel is then delivered to the secondary fuel filter.
The vented fuel from the fuel pressure control valve returns from the secondary fuel filter through the fuel return port and enters the unfiltered side of the fuel conditioning module. Depending on the fuel temperature returning from the secondary fuel filter, the recirculation thermostat directs the fuel to the fuel tank or through the fuel conditioning module back to the inlet of the primary filter.
Fuel Cooler
The fuel cooler is a liquid-to-liquid heat exchanger located on the inside of the left frame rail. Fuel that bypasses the high pressure fuel injection pump and the fuel pressure control valve is subjected to high temperatures. The fuel cooler transfers this heat to the coolant before the fuel is returned to the fuel conditioning module. Refer to Fuel System for additional information.
Fuel Delivery Pressure Switch
The fuel delivery pressure switch is a normally closed switch that monitors the fuel delivery system pressure prior to the high pressure fuel injection pump. The fuel delivery pressure switch opens when the fuel system pressure reaches 365 kPa (53 psi) or above. If the fuel delivery system pressure drops below 365 kPa (53 psi) the switch closes, and if the fuel delivery pressure switch remains closed for more than 60 seconds, the PCM notifies the driver by displaying a low fuel pressure warning in the message center, and an engine derate occurs. The fuel delivery pressure switch is located at the top left of the engine in the fuel injection pump supply tube, forward of the secondary fuel filter.
Fuel Injectors
The fuel injectors are connected to the high pressure fuel rail and deliver a calibrated amount of fuel directly into the combustion chamber. The piezo actuator is commanded on by the powertrain control module (PCM) during the main injection stage for approximately 0-400 microseconds. The fuel injectors on and off time is controlled by the piezo actuator device which allows extreme precision during the injection cycle. For additional information on fuel injection operation, refer to Fuel System.
O-ring and Combustion Gasket
The fuel injector has 1 replaceable O-ring on the fuel return, 1 replaceable O-ring on the fuel injector body and 1 replaceable stepped copper combustion gasket on the tip of the fuel injector.
Piezo Actuator
The piezo actuator consists of a series of small disks. When the piezo actuator is electrically energized, it causes the disks to deform which results in an expansion. The expansion generates a longitudinal motion which pushes down against the valve piston. The piezo actuator returns to its non-energized state by fuel and spring pressure during engine operation, and by the spring pressure from the fuel injector valve return spring when the engine is shut down.
Hydraulic Coupler
The hydraulic coupler transfers the longitudinal movement from the piezo actuator to the fuel injector control valve. It also acts as a seal preventing fuel from entering the piezo actuator device.
Fuel Injector Control Valve
The fuel injector control valve is a hydraulic check valve that allows the high fuel pressure to bleed off into the fuel return chamber directly above it, when the piezo actuator is energized and the valve piston pushes down on it.
Fuel Injector Valve Return Spring
The fuel injector valve return spring holds the fuel injector valve in the sealed position to prevent any fuel from leaking into the fuel return chamber when the piezo actuator is not energized.
Control Piston
The control piston uses its large surface area on top as a downward force to overcome an upward force created by the smaller surface area in the high pressure chamber. The control piston also keeps the nozzle needle in the closed position when the piezo actuator is not energized.
Nozzle Needle and Needle Control Spring
The high pressure chamber uses the high fuel pressure to lift the nozzle needle inwards whenever the piezo actuator is energized. When the nozzle needle is lifted the fuel at the high pressure nozzle is atomized and is injected directly into the combustion chamber through 8 spray holes. The needle control spring holds the nozzle needle in a closed position when the piezo actuator is not energized.
Fuel Pressure Control Valve
The powertrain control module (PCM) controls the fuel rail pressure by activating the fuel pressure control valve which regulates the fuel pressure in the fuel rails. For additional information, refer to Fuel System, Fuel Pump System. The PCM regulates fuel rail pressure by controlling the duty cycle of the fuel pressure control valve solenoid. An increase or decrease in the duty cycle maintains pressure in the fuel system or vents pressure to the fuel cooler. A high duty cycle indicates a high fuel rail pressure is being commanded. A low duty cycle indicates less pressure is being commanded. The fuel pressure control valve is mounted on the fuel rail.
Fuel Volume Contro1 Valve
The powertrain control module (PCM) regulates fuel volume by controlling the duty cycle of the fuel volume control valve. The fuel volume control valve is a normally open valve. A high duty cycle indicates low fuel volume is being admitted to the high pressure fuel injection pump or low pressure. A low duty cycle indicates high volume is being admitted to the high pressure fuel injection pump or high pressure. The fuel volume control valve is mounted on the high pressure fuel injection pump.
