Engine Control Components

ENGINE CONTROL COMPONENTS

Accelerator Pedal Position (APP) Sensor
The APP sensor is a 3-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 3 APP sensor inputs to calculate the desired fuel quantity, injection timing, and the correct injection control 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 3 sensor signals. If the PCM detects a concern on two of the 3 sensor signals, the PCM only allows the engine to operate at idle.

Air Conditioning (A/C) Pressure Switch

A/C Pressure Switch:

The A/C pressure switch is used for additional A/C system pressure control. The A/C pressure switch is also referred to as the refrigerant containment switch.

For refrigerant containment control, the normally closed high pressure contacts open at a predetermined A/C head pressure. This turns off the A/C by opening the A/C demand circuit, preventing the A/C pressure from rising to a level that would open the A/C high pressure relief valve.

Barometric (BARO) Pressure Sensor

Barometric (BARO) Pressure Sensor:

The BARO pressure sensor is a variable capacitor sensor that processes a signal indicating atmospheric pressure. This allows the PCM to compensate for altitude. The PCM uses this information to calculate injection timing and glow plug control. At higher altitudes, glow plug on time is increased to reduce start-up smoke. The BARO sensor is located behind the lower steering column opening finish panel.

A BARO sensor concern results in an out-of-range signal to the PCM.

Boost Pressure Gauge

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.

Brake Pressure Applied (BPA) Switch

Brake Pressure Applied (BPA) Switch:

NOTE: The BPA switch is present on vehicles equipped with speed control.

All vehicles have a single BPA switch. A BPA switch provides a backup for the BPP switch. Normally, a brakes-applied signal from the BPP switch disengages the speed control. If the BPP switch signal is lost, the BPA switch then supplies the brakes-applied signal to the speed control system. The BPA switch signal is also used in the transmission strategy and the key on engine running (KOER) self-test.

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 9.525 mm (0.375 inches) diameter peg approximately 18 degrees wide, projecting 3-5 mm (0.12-0.20 inches) 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. The engine does not operate without a CMP signal.

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).

Cold Idle Kicker
The cold idle kicker strategy provides an increase in idle speed during cold engine warm up.During extended idle conditions, the PCM increases engine speed up to 1,100 RPM (normally 725 RPM for manual, 690 RPM for auto) to achieve a faster engine warm-up. The PCM uses the engine oil temperature (EOT) sensor input and adjusts the RPM accordingly, to a maximum of 1,100 RPM.

The idle speed is increased proportionately when the engine oil temperature is less than 70°C (158°F) and the engine has been at idle for more than 2 minutes. Applying the brake pedal, clutch or accelerator pedal deactivates the cold idle kicker strategy and returns the idle speed to 690 RPM.

Allowing the engine to idle for more than 5 minutes with the EGR valve commanded closed, the variable geometry turbocharger duty cycle may step from 15% to 85%. This occurs momentary and repeats after a calibrated time. For additional information, refer to Powertrain Control Software, Vane Sweep.

Crankshaft Position (CKP) Sensor

Crankshaft Position (CKP) Sensor:

The CKP signal source is a variable reluctance sensor mounted in the right front side of the engine block. The sensor reacts to a target wheel on the crankshaft. The target wheel is a 60 minus 2 tooth steel disk with 58 evenly spaced teeth and a SYNC gap (a minus 2 slot wide tooth). The sensor produces pulses for each tooth edge that passes it. The crankshaft speed is derived from the frequency of the CKP sensor signal. The crankshaft position is determined by synchronizing the SYNC tooth with the SYNC gap signals from the target wheel. Diagnostic information on the CKP input signal is obtained by carrying out accuracy checks on the frequency and duty cycle with software strategies. The PCM uses the CKP and CMP signals to calculate the engine speed and piston position. The CKP creates a signal used by the PCM to indicate cylinder identification in a particular bank. The CKP contains a permanent magnet that creates a magnetic field. The signal is created when the target wheel rotates and breaks the magnetic field created by the sensor. The engine will not operate without a CKP signal.

Electronic Air Filter Restriction Gauge

Air Filter Restriction Indicator (F-Super Duty):

F-Super Duty vehicles are equipped with an electronic air filter restriction gauge located in the air cleaner cover on the clean side of the air filter. The sensor is hardwired to the instrument cluster. When the air flow in the air inlet system reaches the maximum allowable restriction limit, a switch closes and the filter restriction indicator illuminates.

Electronic Variable Geometry Turbocharger (VGT) Control Valve

Electronic Variable Geometry Turbocharger (VGT) Control Valve:

The electronic VGT control valve 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. Therefore, the actuator position is dependent only on the control valve current, it is independent of the hydraulic fluid temperature and viscosity.

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.

If the PCM receives a high engine temperature signal from the ECT, it adjusts fueling rates to protect the engine from damage due to overheating.

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, injection timing, and glow plug operation.

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) Actuator and Valve Position Sensor

EGR Actuator And Valve Position Sensor:

The EGR actuator is a variable position valve that controls the amount of exhaust that enters the intake manifold. The EGR actuator is controlled by the PCM using a pulse width modulated (PWM) signal that varies from 0-100%. The EGR actuator consists of 2 components, a valve with an actuator, and a position sensor to monitor valve movement. The EGR valve position sensor is a potentiometer sensor which is needed to give the control circuit feedback to achieve the desired travel position. When the EGR receives a 5 volt reference signal and a ground from the PCM, a linear analog voltage signal from the sensor indicates the position of the EGR valve. Input signals from the manifold absolute pressure (MAP), exhaust pressure (EP), and barometric pressure (BARO) sensors are used by the PCM to calculate and control the EGR system flow.

Exhaust Gas Recirculation (EGR) System Cooler

EGR System Cooler:

The exhaust gasses are directed through the EGR system cooler 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 system cooler.

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 EP sensor measures the pressure in the LH exhaust manifold. The sensor feedback signal is used for VGT and EGR valve control.

An open or short in the EP sensor wiring results in an out-of-range low voltage at the PCM.

Fan Speed Sensor (FSS)
The FSS is a Hall effect sensor integral to the visctronic drive fan (VDF). The PCM monitors the sensor input and controls the VDF speed based upon the engine coolant temperature, the transmission fluid temperature, and the intake air temperature (IAT) requirements. When an increase in fan speed for vehicle cooling is requested, the PCM monitors the FSS signal and outputs the required PWM signal to a fluid port valve within the VDF.

Glow Plug Indicator Lamp

Glow Plug Indicator:

The glow plug indicator lamp 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 controller area network (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 required.

Injection Control Pressure (ICP) Sensor

Injection Control Pressure (ICP) Sensor:

The ICP 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 primary function of the ICP sensor is to provide a feedback signal to indicate the 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 ICP sensor along with the injection pressure regulator (IPR) form a closed loop fuel pressure control system.

If the PCM detects an inoperative ICP sensor, the PCM controls the injection control pressure from the estimated injection control pressure.

The ICP sensor bias varies between sensors. The amount of voltage the sensor deviates from a calculated reference value (sensor bias) may cause an injection control pressure calculation error.

Injection Pressure Regulator (IPR)

Injection Pressure Regulator (IPR):

The IPR is a PWM variable position valve that regulates the pressure in the ICP system. The IPR restricts the return flow path for oil from the high pressure pump. As the duty cycle increases, the IPR restriction to the drain increases, thus increasing the ICP. The IPR duty cycle is controlled by the PCM and is modulated from 0 to 65% depending upon the desired injection control pressure.

When the starter is engaged and the engine fails to start, the IPR command increases toward its maximum until the engine starts. The normal range for the IPR at idle is between 16-24%. An above 24% range indicates high effort or higher commanded ICP to achieve idle. A below 16% indicates low effort to achieve idle.

An open circuit results in minimal oil pressure and a no-start situation. A short to ground in a circuit results in maximum oil pressure, limited by a mechanical pop-off valve to 27,580 kPa (4,000 psi).

Intake Air Temperature (IAT) Sensor
The IAT sensor is a thermistor device. 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 providing a signal corresponding to temperature.

The 6.0L diesel uses 2 IAT sensors. For vehicles with a mass air flow (MAF) sensor, the IAT sensor is integrated into the MAF sensor. For vehicles without a MAF sensor, the IAT sensor is a stand-alone sensor.

Intake Air Temperature 2 (IAT2) Sensor

Intake Air Temperature 2 (IAT2) Sensor:

The IAT2 or manifold air temperature (MAT) sensor is a thermistor device. 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 providing a signal corresponding to temperature.

The IAT2 sensor is located in the intake manifold. The sensor provides a manifold air temperature signal to the PCM. The PCM uses the IAT2 signal to control timing and fuel rate during cold starts and provide an input to the cold idle kicker.

Manifold Absolute Pressure (MAP) Sensor

Manifold Absolute Pressure (MAP) Sensor:

The MAP sensor is a variable capacitor sensor that is supplied a 5-volt reference signal by the 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 signal is used to control smoke by limiting fuel quantity during acceleration until a specified boost pressure is obtained, and is used by the PCM for EGR system calculations and control.

A MAP signal concern detected by the PCM causes the PCM to calculate an estimated manifold pressure based on known engine conditions.

Mass Air Flow (MAF) Sensor

F-Super Duty Mass Air Flow (MAF) Sensor:

Mass Air Flow (MAF) Sensor (E-Series):

The MAF sensor provides an analog voltage signal to the 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 200°C (392°F) above the ambient temperature. 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 mass flow. The MAF signal is used to calculate the EGR flow rate and for concern detection.

The current PCM implementation contains a mass air flow interface, which consists of a 2-pole, differential input, low pass filter. This filter is designed to pass an analog signal, originating from the mass air sensor, while rejecting unwanted ignition noise, high frequency electrical interference, and ground offsets. The input to the interface is the analog voltage signal difference between MAF+ (mass air flow signal) and MAF- (mass air flow return). The MAF sensor output an analog voltage signal calibrated to 0.5 V at the lower limit of the flow range and 4.75 V at the upper limit of the flow range.

Output Shaft Speed (OSS) Sensor

Output Shaft Speed (OSS) Sensor:

The OSS sensor detects the speed of the transmission output shaft. The sensor uses variations in a magnetic field caused by the OSS sensor gear to generate an output signal corresponding to shaft speed. The OSS sensor gear uses a repetitive pattern of 3 different angular displacements between the teeth. The magnetic sensor element may be a Hall effect sensor or magnetic pick-up. Due to the open collector design and the RC timing involved in the pull-up, the rising edge of the OSS sensor gear is not a reliable edge for critical timing, only the falling edge. The pull-up resistor is located in the PCM to provide a current for the sensor. This applies specifically to the automatic transmission.

Parking Brake Switch
The parking brake switch signal indicates when the parking brake is applied. On all vehicles, the parking brake switch is located under the instrument panel. The parking brake switch deactivates the speed control if the brake is applied during speed control operation and provides a brake input for the cold idle kicker.

Passive Anti-Theft System (PATS)
The PATS prevents engine operation without the correctly encoded key.

Tachometer

Tachometer:

The tachometer is controlled by the instrument cluster. The PCM sends an engine speed message through the CAN to the instrument cluster indicating the engine RPM.

Transmission Control Switch (TCS)

Typical Column-Shift Transmission Control Switch (TCS):

On automatic transmission equipped vehicles, the TCS provides an input signal to the PCM whenever the switch is pressed. For F-Super Duty, the tow/haul indicator illuminates when the TCS is cycled to engage and disengage the tow/haul strategy. For E-Series, the overdrive cancel indicator illuminates when the TCS is cycled to engage or disengage the overdrive function of the transmission.

Visctronic Drive Fan (VDF)

Visctronic Drive Fan (VDF):

The VDF is an electrically actuated viscous clutch that consists of 3 main elements:
- a working chamber
- a reservoir chamber
- an actuator (electromechanical valve and speed sensor)

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 via a pulse width module (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 diagnostic trouble code (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.

Water-in-Fuel Indicator

Water-In-Fuel Indicator:

The water-in-fuel indicator is controlled by the instrument cluster. The cluster receives electronic information from the PCM through the CAN. If the water-in-fuel sensor indicates that there is water in the fuel separator/housing (located within the fuel conditioning module), the PCM sends a message to illuminate the water-in-fuel indicator.

4x4 Low Switch
The 4x4 low switch provides a signal to the instrument cluster when 4x4 low is selected. This input is used to adjust the shift schedule. Using the controller area network (CAN) (F-Super Duty) the instrument cluster provides a four wheel drive (4WD) status signal to the PCM.