Fu-Tu
Fuel Volume Control ValveThe 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.
Fuel Rail Pressure (FRP) Sensor
The fuel pressure sensor is a 3 wire variable capacitance sensor located at the front of the left hand side fuel rail. The powertrain control module (PCM) supplies a 5 volt reference (VREF) signal which the FRP sensor uses to produce a linear analog voltage that indicates high fuel pressure. The primary function of the FRP sensor is to provide a feedback signal to the PCM indicating the pressure of the fuel in the fuel rail. The PCM monitors FRP as the engine is operating to control fuel pressure. This is a closed loop function which means the PCM continuously monitors and adjusts for ideal fuel rail pressure determined by conditions such as engine load, speed and temperature. The fuel rail pressure can be monitored by viewing the scan tool FRP (volts) and FRP_A (pressure) PIDs.
Fuel Rail Temperature (FRT) Sensor
The FRT 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 sensor is located at the top left of the engine in the fuel injection pump supply tube, forward of the secondary fuel filter. 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 fuel injector timing, the pulse width, and the correct injection control pressure for correct fuel delivery at all speed and load conditions.
Glow Plug
The glow plug improves ignition during cold engine starts by providing a heat source for combustion to improve cold engine starting and operation. The glow plugs are made of a resistive material that heats up when electricity flows through it. The glow plugs are duty cycle controlled by the glow plug control module (GPCM) and activated when modulated voltage is supplied to them. The ceramic instant start glow plugs can operate up to 20 minutes. The glow plugs may turn back on at cold ambient extended idle. The GPCM provides battery voltage for approximately 2 seconds to rush current and heat up the glow plugs, then drop back to 7 volts lowering the amperage. For additional information on glow plug system operation, refer to Powertrain Control Hardware Glow Plug Control Module (GPCM).
Glow Plug Indicator
The glow plug indicator is located in the instrument panel cluster and informs the operator when the engine is ready to be started. The indicator is controlled by the instrument panel cluster based on an electronic command signal from the PCM through the CAN. The on-time of the indicator 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
The high pressure fuel injection pump is gear driven by the camshaft gear and is located at the front of the engine. It increases the fuel pressure from approximately 414 kPa (70 psi) up to 200 MPa (29,007 psi) and delivers it to the fuel rails.
Inertia Fuel Shutoff (IFS) Switch
The purpose of the IFS switch is to shut off the fuel pump if a collision occurs. It is located in the right hand side of the instrument panel and consists of a steel ball held in place by a magnet. When an impact occurs, the ball breaks loose from the magnet, rolls up a conical ramp and strikes a target plate opening the electrical contacts of the switch and turning off the electric fuel pump in the fuel conditioning module. Once the switch is open, it must be manually reset before restarting the vehicle. To reset the IFS switch, push the button on top of the switch down.
Intake Air Temperature (IAT) Sensor
The IAT 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 IAT sensor is integrated with the mass air flow (MAF) sensor, known as the MAF/IAT sensor.
The MAF/IAT sensor is located in the intake air tube between the air filter housing and the turbocharger intake.
Intake Throttle
The intake throttle modulates the intake air flow from the charge air cooler (CAC) into the intake manifold system. The intake throttle uses an electric motor to open and close a throttle plate, based upon inputs from the powertrain control module (PCM). The intake throttle actuator is controlled by a pulse width modulated (PWM) signal to attain the desired position using the TACM+ and TACM- circuits. The throttle position ranges between 0%, or fully open, and 100%, or fully closed.
The PCM senses the intake throttle plate position by monitoring the TP circuit. If the PCM detects an intake throttle plate position concern, a DTC sets indicating the throttle plate is either not at the desired position or the TP circuit is out of range.
Manifold Absolute Pressure (MAP) Sensor
The MAP sensor is a 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 MAP sensor allows the PCM to determine the engine boost to calculate fuel quantity. In addition, the MAP sensor signal is used by the PCM for EGR system calculations and control.
Mass Air Flow (MAF) Sensor
The MAF sensor provides a signal to the powertrain control module (PCM) proportional to the intake air mass. The MAF sensor uses a hot wire sensing element to measure the amount of air entering the engine. The hot wire is maintained at a constant temperature above ambient. Air passing over the hot wire cools the wire. The current required to maintain the temperature of the hot wire is proportional to the air flow.
The MAF sensor is a digital sensor that provides an output signal of varying frequency. The signals time period is proportional to the flow rate crossing the sensor. The greater the air flow the shorter the time period. The time period varies from 1480 microseconds at a low flow or idle condition, to 106 microseconds at a high flow rate condition.
The MAF sensor is integrated with the intake air temperature (IAT) sensor, known as the MAF/IAT sensor.
The MAF/IAT sensor is located in the intake air tube between the air filter housing and the turbocharger intake.
Nitrogen Oxides (NOx) Module
The NOx module monitors the NOx sensor and controls the NOx sensor heater element. The NOx module communicates with the PCM through the high speed controller area network (HS CAN) to report NOx concentrations, oxygen (O2) concentrations, and NOx sensor system concerns.
The NOx module consists of a microprocessor, RAM, ROM, EEPROM, heater driver, and temperature sensor. The EEPROM stores the module calibration. The heater driver supplies a pulse width modulated (PWM) voltage to the heater portion of the sensor to maintain operational temperature. The microprocessor processes all of the inputs from the sensor and communicates the information to the PCM. The temperature sensor in the module is used for compensating the temperature dependency of circuit components and for module and sensor rationality checks.
Nitrogen Oxides (NOx) Sensor
The NOx sensor detects the presence of oxygen (O2) and NOx concentrations in the exhaust system. The NOx Sensor uses two measurement chambers to determine O2 and NOx concentrations. The O2 concentration is measured in the first measurement chamber. Exhaust gas enters the first chamber through a diffusion barrier. The sensor infers an air fuel ratio relative to the stoichiometric air fuel ratio by balancing the amount of oxygen pumped in or out of the measurement chamber. As the exhaust gases become richer or leaner, the amount of oxygen that must be pumped in or out to maintain a stoichiometric air fuel ratio in the measurement chamber varies in proportion to the air fuel ratio. The amount of current required to pump the oxygen in or out of the measurement chamber calculates the air fuel ratio. The calculated air fuel ratio is the output from the pumping current controller in the NOx module and not a signal directly from the sensor.
The NOx concentration measurement takes place in the second measurement chamber. Exhaust gas passes from the first measurement chamber through a second diffusion barrier into the second measurement chamber. The NOx present in the second measurement chamber is dissociated into nitrogen (N2) and O2. The excess O2 is pumped out of the measurement chamber by the pumping current. The amount of current required to pump the oxygen ions out of the measurement chamber calculates the NOx content. The calculated NOx content is the output from the pumping current controller in the NOx module and not a signal directly from the sensor.
The NOx sensor is equipped with a memory component which stores gain and offset characteristics of the sensor to compensate for part to part variation of the element during the manufacturing process.
Power Take Off
The PTO system provides an input signal to the PCM indicating there is an additional load being applied to the engine. The PCM disables the on-board diagnostic (OBD) monitors and increases the engine RPM based on the PTO system or auxiliary idle control input.
Powertrain Secondary Cooling System Coolant Pump
The belt-driven powertrain secondary cooling system coolant pump is mounted to the front of the engine and circulates the coolant which cools the fuel in the fuel cooler system, in addition to cooling other powertrain components. Refer to Fuel System, Fuel Cooling for additional information.
Reductant Heater and Sender Assembly
The reductant heater and sender assembly contains the pickup tube for the reductant pump module, an electric heating element, a reductant temperature sensor, and an electrode-type level sensor.
The heating element is directly above the pickup tubes inlet filter. When the reductant temperature sensor detects the diesel exhaust fluid (DEF) temperature dropping to its freezing point of -11°C 12°F), the PCM commands the glow plug control module (GPCM) to provide voltage to the heating element. The heating element thaws and maintains a pool of liquid reductant within the reductant heater and sender assembly reservoir during cold ambient temperatures.
The reductant level sensor incorporates four stainless steel electrodes, with three electrodes arranged vertically to provide a high, middle, and low level signal. The fourth electrode runs the length of the level sensor and acts as a ground. The DEF is a good conductor of electricity. When the reductant tank is full, the DEF closes a circuit between all three level electrodes and the ground electrode, indicating the tank is full. As the DEF is consumed, the level drops and uncovers each electrode in sequence. The PCM calculates the DEF level based on these signals.
Reductant Heaters
The reductant heaters maintain the diesel exhaust fluid (DEF) in a liquid state during cold ambient temperatures. There are three heating elements in the system, each receiving voltage from the glow plug control module (GPCM). The reductant pressure line heater is integral to the reductant pressure line. The reductant tank heater is integral to the reductant heater and sender assembly. For additional information on the reductant tank heater, refer to the reductant heater and sender assembly description. The reductant pump heater is integral to the reductant pump assembly. For additional information on the reductant pump heater, refer to the reductant pump assembly description.
Reductant Injector
The reductant injector is a pulse width modulated (PWM) solenoid controlled directly by the PCM. The injector receives diesel exhaust fluid (DEF) from the reductant pressure line and sprays it into the exhaust stream, where it is mixed into the exhaust gases before entering the selective catalytic reduction (SCR) catalyst.
Reductant Level Sensor
The reductant level sensor provides the reductant tank level to the PCM. The reductant level sensor is integral to the reductant heater and sender assembly. For additional information on the reductant level sensor, refer to the reductant heater and sender assembly description.
Reductant Pressure Sensor
The reductant pressure sensor provides feedback to the PCM, which regulates system pressure by controlling pump speed using pulse width modulation (PWM). The reductant pressure sensor is integral to the reductant pump assembly. For additional information on the reductant pressure sensor, refer to the reductant pump assembly description.
Reductant Pump Assembly
The reductant pump assembly contains a diaphragm pressure pump, a pressure sensor, a purge valve, an outlet filter, and an internal heating element.
The reductant pressure sensor provides feedback to the PCM, which regulates system pressure by controlling pump speed using pulse width modulation (PWM).
When the PCM requests reductant injection, the reductant injector opens and the pump operates, filling the reductant pressure line and injector and purging air from the system. When all air is purged, the injector closes and the pump builds pressure to 500 kPa (73 psi). The system is then primed and the injector provides diesel exhaust fluid (DEF) to the selective catalytic reduction (SCR) catalyst as commanded by the PCM.
When the vehicle is shut down, the PCM closes the injector and actuates the reductant purge valve, causing the pump to reverse flow and bleed down pressure on the reductant pressure line. The PCM then opens the injector to allow gas to enter the reductant pressure line, which in turn allows the pump to purge all remaining DEF from the system and return it to the reductant tank. The PCM closes the injector and returns the purge valve to the forward position.
The PCM commands the glow plug control module (GPCM) to provide voltage to the reductant pump assembly internal heating element when the reductant temperature approaches -11°C (12°F).
Reductant Purge Valve
The reductant purge valve allows the reductant pump assembly to reverse flow and purge the system when commanded by the PCM. The reductant purge valve is integral to the reductant pump assembly. For additional information on the reductant purge valve, refer to the reductant pump assembly description.
Reductant Temperature Sensor
The reductant temperature 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 reductant temperature sensor provides feedback to the PCM, which controls the reductant heaters to keep the reductant in a liquid state during low ambient temperatures. The reductant temperature sensor is integral to the reductant heater and sender assembly. For additional information on the reductant temperature sensor, refer to the reductant heater and sender assembly description.
Secondary Cooling System Engine Coolant Temperature 2 (ECT2) Sensor
The secondary cooling system ECT2 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 powertrain control module (PCM) corresponding to temperature.
The secondary cooling system ECT2 sensor is located in the exhaust gas recirculation (EGR) cooler. The secondary cooling system ECT2 sensor measures the temperature of the secondary cooling system and provides a feedback signal to the PCM. The PCM uses the secondary cooling system ECT2 sensor input to control the EGR cooler bypass valve.
Selective Catalytic Reduction (SCR) Catalyst
The SCR catalyst reduces nitrogen oxides (NOx) present in the exhaust stream to nitrogen (N2) and water (H2O). The SCR catalyst contains a copper catalyst washcoated on a zeolite substrate. At the inlet of the SCR catalyst is a port for the reductant injector, followed by a louvered diffuser and a twist mixer. The reductant diesel exhaust fluid (DEF) is a solution of urea in deionized water. The urea solution percentage for correct SCR system operation is 28 - 35%. When DEF is introduced into the system, it finely atomizes in the louvered diffuser and mixes evenly with exhaust gases in the twist mixer. During this time, the heat of the exhaust gases causes the urea to split into carbon dioxide (CO2) and ammonia (NH3). As the ammonia and NOx pass over the SCR catalyst, a reduction reaction takes place and the ammonia and NOx are converted to N2 and H2O. This reaction takes place at up to 95% efficiency and allows the engine to run leaner and more efficiently, since the high NOx levels that are produced under lean conditions are eliminated.
Turbocharger
The dual boost turbocharger used on the wide frame vehicles is a 3 wheel design with a single turbine and 2 compressor wheels placed back to back. The 2 compressor wheels are similar to each other. They have the same diameter and are optimized to reduce pressure differences that could cause noise or air flow issues. The standard 2 wheel design is used on the narrow frame vehicles.
The turbocharger uses variable vanes that surround the turbine wheel to dynamically adjust turbocharger speed using exhaust gases. During engine operation at low speeds and load, the vanes are closed to accelerate exhaust gases across the turbine wheel to help quickly increase turbo wheel speed. At high speeds the vanes open to prevent turbocharger overspeed conditions.
The turbocharger uses a ball bearing cartridge that surrounds the turbocharger shaft to help provide a decrease in spool up times. Separate oil and water feeds flow through the turbo mounting pedestal to lubricate and cool the turbocharger to eliminate as many external connections as possible. The front of the pedestal houses the turbocharger oil filter.
The turbocharger provides up to approximately 206.84 kPa (30 psi) boost at up to 130,000 RPM.
Turbocharger Actuator
The turbocharger actuator is a 4-way proportional hydraulic flow control valve with a closed center position. The valve controls the linear actuator position of a closed loop hydraulic servo by charging and venting the flow on both sides of a piston. Linear displacement feedback from the actuator varies a feedback spring force to move the valve spool to the center closed position when the actuator reaches the desired position. The actuator position is dependent only on the control valve current and not on the hydraulic fluid temperature and viscosity.
Turbocharger Wastegate
The turbocharger wastegate is a mechanically activated valve located in the turbine housing of the turbocharger. It is opened and closed by the vacuum operated turbocharger wastegate actuator dependent on the amount of boost the powertrain control module (PCM) to is requesting for the current driving conditions. The wastegate allows exhaust gases to bypass the turbine to vary the speed of the compressor wheel in conjunction with the variable vanes used on the turbine. This configuration provides for more precise control of the turbocharger boost output.
Turbocharger Wastegate Actuator
The turbocharger wastegate actuator is a canister device containing a diaphragm controlled by an applied vacuum. The diaphragm is attached to a connecting rod that is attached to the turbocharger wastegate. The vacuum source applied to the turbocharger wastegate actuator is controlled by the powertrain control module (PCM) to using the turbocharger wastegate regulating valve solenoid to vary the amount of vacuum applied to the diaphragm.
Turbocharger Wastegate Regulating Valve Solenoid
The turbocharger wastegate regulating valve solenoid allows the powertrain control module (PCM) to indirectly control the turbocharger wastegate. The turbocharger wastegate regulating valve solenoid controls the vacuum to a pneumatically powered wastegate actuator in order to control the boost pressure limit. When the PCM commands the turbocharger wastegate regulating valve solenoid to allow the vacuum applied to the pneumatically powered actuator to increase, the turbocharger wastegate opens and the compressor outlet pressure is limited.
The turbocharger wastegate regulating valve solenoid supplies vacuum to the pneumatically powered wastegate actuator diaphragm, which regulates the maximum boost pressure to a constant value. A vacuum greater than 32 kPa (9.45 in-Hg) on the pneumatically powered wastegate actuator opens the wastegate. The turbocharger wastegate regulating valve solenoid can partially vent (reduce) the control vacuum, resulting in increased regulated maximum boost.
