Part 1
ENGINE CONTROL COMPONENTSAccelerator Pedal Position (APP) Sensor
Accelerator 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 illuminates 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
Air Filter Restriction Gauge:
An electronic air filter restriction gauge is located in the air cleaner housing. The sensor is hardwired to the instrument cluster. When the air flow in the intake air system reaches the maximum allowable restriction limit, a switch in the air filter restriction gauge closes and a message is displayed in the message center of the instrument cluster.
Boost Pressure Gauge
The boost pressure gauge is controlled by the instrument cluster. The PCM sends a message through the controller area network (CAN) to the instrument cluster indicating engine boost pressure.
Brake Pedal Position (BPP) Switch
Brake Pedal Position (BPP) Switch:
The BPP switch signals the PCM with a battery positive voltage (B+) signal whenever the brake pedal is applied. The signal informs the PCM to disengage the torque converter clutch, speed control, and auxiliary idle control (if equipped).
If all the stoplamp bulbs are burned out (open), a high voltage is present at the PCM due to a pull-up resistor in the PCM. This provides fail-safe operation in the event the circuit to the BPP switch has failed.
Camshaft Position (CMP) Sensor
Camshaft Position (CMP) Sensor:
The CMP sensor is a variable reluctance sensor that responds to a rotating trigger protruding from the camshaft. The trigger is a single peg projecting from the camshaft. The peg passes the sensor once per camshaft revolution and produces a single pulse. The camshaft speed is calculated from the frequency of the CMP sensor signal. If the CMP sensor signal is lost while the engine is running, the engine continues to operate. The loss of the CMP signal while starting the engine will cause a no start condition.
Charge Air Cooler (CAC)
Charge Air Cooler (CAC):
The CAC is composed of a radiator mounted in the grill 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 outside air reducing the temperature of the intake air.
Clutch Pedal Position (CPP) Switch
Clutch Pedal Position (CPP) Switch:
The CPP switch provides an input to the PCM indicating the clutch pedal position. The CPP switch A is a normally open switch that indicates clutch disengagement (bottom of travel). CPP switch B is a normally closed switch that indicates clutch engagement (top of travel).
Cooling Fan
Cooling Fan:
The 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 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 the fan speed based on the engine coolant temperature, the engine oil 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 is set 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.
Crankshaft Position (CKP) Sensor
Crankshaft Position (CKP) Sensor:
The CKP sensor is a magnetic transducer mounted on the engine block, adjacent to a pulse wheel located on the crankshaft. The pulse wheel is a 60 minus 2 tooth steel disk with 58 evenly spaced teeth and a minus 2 tooth slot. As the crankshaft rotates, the CKP produces a sine wave for each tooth edge of the pulse wheel and it detects the missing 59th and 60th tooth. This configuration allows the CKP sensor to provide the PCM with the angular position of the 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
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). At this temperature the soot in the diesel particulate filter burns and becomes ash. 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
Diesel Particulate Filter Pressure Sensor:
The diesel particulate filter pressure sensor is an input to the PCM and is used to measure the pressure before the diesel particulate filter. The sensor is a differential-type sensor that is referenced to atmospheric pressure. 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).
Engine Coolant Temperature (ECT) Sensor
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 resistance increases as the temperature decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signals to the PCM corresponding to temperature.
A cooling system concern such as low coolant or coolant loss could cause an overheating condition. As a result, damage to major engine components could occur. Using both the ECT sensor and fail-safe cooling strategy, the PCM prevents damage by allowing air cooling of the engine and limp home capability.
Engine Oil Temperature (EOT) Sensor
Engine Oil Temperature (EOT) Sensor:
The EOT sensor is a thermistor whose resistance decreases as engine oil temperature increases. The EOT signal is used by the PCM 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.
An EOT signal detected out of range, high or low, by the PCM causes the PCM to substitute a temperature based on the ECT to be used for operating purposes.
Exhaust Gas Recirculation (EGR) Oxidation Catalytic Converter (OC)
Exhaust Gas Recirculation (EGR) Oxidation Catalytic Converter (OC):
The EGR OC helps keep the EGR coolers clean by removing deposits and exhaust condensation, and preventing corrosion in downstream components.
Exhaust Gas Recirculation (EGR) Coolers
Exhaust Gas Recirculation (EGR) Coolers:
The exhaust gasses are directed through 2 EGR coolers to remove heat before the gasses arrive at the EGR valve. Engine coolant is used to reduce the exhaust gas temperature by directing coolant flow through the EGR coolers.
Exhaust Gas Recirculation Temperature (EGRT) Sensor
Exhaust Gas Recirculation Temperature (EGRT) Sensor:
The EGRT sensor is a thermistor device that monitors the exhaust gas temperature before the EGR coolers. The electrical resistance of a thermistor decreases as the temperature increases, and resistance increases as the temperature decreases. The varying, non-linear resistance affects the voltage drop across the sensor terminals and provides an electrical signal to the PCM that corresponds to measured temperature.
The temperature range of the sensor is between 200°C (392°F) and 900°C (1,652°F) and cannot be accurately measured at room temperature. The nominal output signal voltage range measures 4.6 volts, for temperatures between -40°C (-40°F) and 200°C (392°F) and 0.21 volt at 900°C (1,652°F).
The EGRT sensor is used to determine whether the EGR coolers are operating correctly.
Exhaust Gas Recirculation Temperature 2 (EGRT2) Sensor
Exhaust Gas Recirculation Temperature 2 (EGRT2) Sensor:
The EGRT2 sensor is a thermistor device that monitors the exhaust gas temperature after the EGR coolers. The electrical resistance of a thermistor decreases as the temperature increases, and resistance increases as the temperature decreases. The varying, non-linear resistance affects the voltage drop across the sensor terminals and provides an electrical signal to the PCM that corresponds to the measured temperature.
At approximately 25°C (77°F) with the key ON engine OFF, the temperature signal of the sensor is approximately 4.5 volts while connected to the PCM.
The temperature signal range of the sensor is 4.65 volts at -40°C (-40°F) and 0.25 volt at 300°C (572°F).
The EGRT2 sensor is used to determine whether the EGR coolers are operating correctly.
Exhaust Gas Recirculation (EGR) Valve
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 PCM controls the EGR valve which operates between -100 and 100% duty cycles which cannot be viewed by a PID on a scan tool.
The EGR valve operation can be monitored by viewing the EGRVPA PID which displays the actual EGR valve position as a percentage.
Exhaust Gas Recirculation (EGR) Valve Position Sensor
Exhaust Gas Recirculation (EGR) Valve Position Sensor:
The EGR valve position sensor is a potentiometer sensor that monitors the EGR valve movement. The valve position signal is monitored for the desired EGR valve travel position. The sensor is integral to the EGR valve.
Exhaust Gas Temperature (EGT) Sensor
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 3 EGT sensors to monitor the exhaust gas temperature. The first sensor is located before the OC. The second sensor is located between the OC and diesel particulate filter. The third sensor is located after the diesel particulate filter.
Exhaust Pressure (EP) Sensor
Exhaust Pressure (EP) Sensor:
The EP sensor is a variable capacitor sensor that is supplied a 5-volt reference signal by the 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, located at the left rear of the engine, measures the pressure in the exhaust manifold. The sensor feedback signal is used for variable turbocharger geometry and EGR valve control.
An open or short in the EP sensor wiring results in an out-of-range high or low voltage, at the PCM.
The output of the sensor ranges from 0.175 volt at 28.6 kPa (4.15 psi) to 4.825 volts at 616.5 kPa (89.42 psi). At an atmospheric pressure of 101 kPa (14.65 psi) the output of the sensor is between 0.67 and 0.82 volt.
Fan Speed Sensor (FSS)
The FSS is a Hall effect sensor integral to the cooling fan. The PCM monitors the sensor input and controls the cooling fan speed based upon the engine coolant temperature (ECT), the transmission fluid temperature, and the intake air temperature (IAT) 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 Cooler
Fuel Cooler:
The fuel cooler is a liquid-to-liquid heat exchanger. It is located on the top, left side of the engine and it transfers heat contained in the fuel to the coolant.
Fuel Cooler Pump
Fuel Cooler Pump:
The fuel cooler pump is mounted to the cooling fan shroud on the driver's bottom side and it circulates the coolant which cools the fuel in the fuel cooler system. The PCM commands the fuel cooler pump on by grounding the pump circuit when the fuel temperature exceeds the calibrated threshold.
Fuel Conditioning Module
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 1.27 cm (1/2 inch) fuel supply line. When the fuel enters the fuel conditioning module it flows through the 10 micron fuel filter which separates particles and removes water 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 turns the WIF indicator ON. The conditioned fuel is then delivered to the secondary fuel filter.
The unused fuel returns from the secondary fuel filter through the 0.95 cm (3/8 inch) 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 Injectors
Fuel Injector (Part 1):
Fuel Injector (Part 2):
The fuel injectors are connected to the high pressure fuel rail and deliver a calibrated amount of fuel directly into the combustion chamber. The injectors on and off time is controlled by the piezo actuator device which allows extreme precision during the injection cycle. The piezo actuator is commanded on by the PCM during the main injection stage for approximately 0-400 micro seconds.
O-ring and Combustion Gasket
The fuel injector has 1 replaceable O-ring on the outside of the body, and 1 replaceable steel combustion gasket on the tip of the 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 downward 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.
Valve Piston
The valve piston is used to transfer the longitudinal movement from the piezo actuator to the fuel injector valve. It also acts as a seal preventing fuel from entering the piezo actuator device.
Fuel Injector Valve
The fuel injector 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 6 spray holes. The needle control spring is used to hold the nozzle needle in a closed position when the piezo actuator is not energized.
Fuel Level Input
Fuel level information is sent from the instrument cluster to the PCM on the controller area network (CAN) communication link.
Fuel Pressure Control Valve
Fuel Pressure Control Valve:
The PCM controls the fuel rail pressure (FRP) by activating the fuel pressure control valve which regulates the fuel pressure at the outlet of the high pressure fuel injection pump. The PCM regulates FRP by controlling the on/off time of the fuel pressure control valve solenoid. An increase or decrease in the on/off time positions maintains pressure in the fuel system or vents pressure to the fuel cooler. A high duty cycle indicates a high FRP is being commanded. A low duty cycle indicates less pressure is being commanded. The fuel pressure control valve is mounted on the top rear of the engine in the high pressure fuel injection pump cover and is integrated to the high pressure fuel injection pump.
Fuel Volume Control Valve
Fuel Volume Control Valve:
The PCM controls the volume of low pressure fuel that enters the inlet one-way check valve and 3 main pump pistons by activating the fuel volume control valve. The PCM regulates fuel volume by controlling the on/off time of the fuel volume control valve solenoid. A high duty cycle indicates a high fuel volume is being commanded. A low duty cycle indicates less volume is being commanded. The fuel volume control valve is mounted on the top rear of the engine in the high pressure fuel injection pump cover and is integrated to the high pressure fuel injection pump.
Fuel Rail Pressure (FRP) Sensor
Fuel Rail Pressure (FRP) Sensor:
The FRP sensor is a diaphragm strain gauge device in which resistance changes with pressure. The electrical resistance of a strain gauge increases as pressure increases, and the resistance decreases as the pressure decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signals to the PCM corresponding to pressure. The FRP sensor is located on the fuel rail and its primary function is to provide a feedback signal to indicate the fuel rail pressure so that the PCM can command the correct injector timing, pulse width, and the correct injection control pressure for proper fuel delivery at all speed and load conditions. The FRP sensor along with the fuel pressure control valve form a closed loop fuel pressure control system.
Fuel Rail Temperature (FRT) Sensor
Fuel Rail Temperature (FRT) Sensor:
The FRT sensor is a thermistor device in which resistance changes with temperature and is located at the base of the secondary fuel filter housing. The electrical resistance of the 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 feedback signal to the PCM corresponding to temperature. The FRT sensor measures the temperature of the fuel at the secondary fuel filter and provides a feedback signal to the PCM. The PCM uses the FRT sensor input to command the correct injector timing, pulse width, and the correct injection control pressure for proper fuel delivery at all speed and load conditions.
Glow Plug
Glow Plug:
The glow plug improves ignition during cold engine starts by heating air in the combustion chamber when the key is first turned on. The glow plugs are made of a resistive material that heats up when electricity flows through it. The glow plugs are controlled by the glow plug control module (GPCM) and are activated when direct battery voltage is applied.
Glow Plug Indicator
The glow plug indicator is located in the instrument cluster and is used to inform the operator when the engine is ready to be started. The indicator is controlled by the instrument cluster based on an electronic command signal from the PCM through the CAN. The on-time normally varies between 1 and 10 seconds and is independent of the glow plug relay on-time. As a prove out, the indicator is commanded on at every key cycle even though the glow plug system may not be operating.
High Pressure Fuel Injection Pump
High Pressure Fuel Injection Pump:
The high pressure fuel injection pump is gear driven by the camshaft gear and is located at the rear of the engine. It increases the fuel pressure from approximately 34.5-41.3 kPa (5-6 psi) up to 169.96 MPa (24,650 psi) and delivers it to the fuel rails.