Diesel PCM Inputs
DIESEL PCM INPUTS
Accelerator Pedal Position (APP) Sensor
The accelerator pedal position (APP) sensor is a three-track potentiometer that is used to calculate fuel quantity. The sensor receives VREF voltage from the powertrain control module (PCM) and provides a variable voltage signal directly proportional to the accelerator pedal position. A PCM detected fault of one of the three sensor track signals will illuminate the malfunction indicator (MIL) and permit normal operation. A fault with two sensor signals will illuminate the MIL and only allow the engine to operate at idle.
Air Conditioning Pressure Switch
Air Conditioning Pressure Switch:
The A/C Pressure Switch (ACPSW) is used for additional A/C system pressure control. The ACPSW 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.
An Excursion may be equipped with the optional Electronic Automatic Temperature Control (EATC).
Analog Manifold Absolute Pressure Sensor
Analog Manifold Absolute Pressure (MAP) Sensor:
The analog Manifold Absolute Pressure (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 intake manifold pressure. The sensor voltage increases as pressure increases. The MAP sensor allows the PCM to determine engine load 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 utilized by the PCM for EGR system calculations and control.
A MAP signal fault detected by the PCM will cause the PCM to calculate an estimated manifold pressure based on known engine conditions.
Barometric Pressure Sensor
Barometric Pressure (BARO) Sensor:
The Barometric Pressure (BARO) 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. The BARO sensor is located behind the lower steering column opening finish panel.
A BARO sensor fault will result in an out-of-range signal to the PCM.
Brake Pedal Position (BPP) Switch
Brake Lamp Switch:
The Brake Pedal Position (BPP) switch signals the PCM with a battery positive voltage (B+) signal whenever the vehicle 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 Brake Pedal Position switch has failed.
Brake Pressure Applied Switch
Brake Pressure Applied Switch:
NOTE: The Brake Pressure Applied Switch is present on vehicles equipped with speed control.
All vehicles have a single Brake Pressure Applied (BPA) switch. A BPA switch provides a backup for the Brake Pedal Position (BPP) switch. Normally, a brakes-applied signal from the BPP switch will disengage the speed control. If the BPP switch signal is lost, the BPA switch will then supply the brakes-applied signal to the speed control system.
Camshaft Position Sensor
Camshaft Position (CMP) Sensor:
The Camshaft Position (CMP) sensor is a variable reluctance sensor, which will respond to a rotating trigger protruding from the camshaft. The trigger is a single 9.525 mm diameter peg approximately 18 camshaft degrees wide, projecting 3-5 mm from the camshaft. The sensor will produce a sine wave in response to the peg as it passes the sensor. The sensor output is required to determine camshaft position.
Clutch Pedal Position Switch
Clutch Pedal Position (CPP) Switch:
The Clutch Pedal Position (CPP) switch is an input to the Powertrain Control Module (PCM) indicating the clutch pedal position. The CPP sends battery voltage to the PCM when the clutch is engaged (foot off of pedal) and zero voltage when the clutch is disengaged (pedal depressed).
Cold Idle Kicker
Cold Idle kicker provides an increase in idle speed during cold engine warm up, of up to 1100 rpm (normally 700 rpm for manual, 625 RPM for auto), for a faster warm-up to operating temperature during extended idle conditions. This is accomplished by the PCM, which monitors the EOT sensor input and adjusts the RPM accordingly, to a maximum of 1100 RPM.
The idle speed is increased proportionately when the engine oil temperature is below 70°C (158°F) and the engine has been at idle for more than 2 minutes.
Crankshaft Position Sensor
Crankshaft Position (CKP) Sensor:
The Crankshaft Position (CKP) sensor is a variable reluctance sensor which will respond to a rotating actuator positioned on the crankshaft. The actuator is a 60-2 tooth steel disk with 58 evenly spaced teeth and a minus 2 tooth slot. The sensor will produce a sine wave for each tooth edge of the actuator. The sensor's output is required to determine crankshaft speed, position and acceleration.
Engine Coolant Temperature (ECT) Sensor
Engine Coolant Temperature (ECT) Sensor:
The Engine Coolant Temperature (ECT) sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases, and 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 will adjust fueling rates to protect the engine from damage due to overheating.
Engine Oil Temperature Sensor
Engine Oil Temperature (EOT) Sensor:
The Engine Oil Temperature (EOT) sensor is a thermistor whose resistance decreases as engine oil temperature increases. The Engine Oil Temperature signal is used by the PCM to calculate fuel quantity, injection timing and glow plug operation.
At low ambient air temperatures, and oil temperature below 70°C (158°F), low idle is increased to a maximum of 1300 rpm to increase engine warm-up. Fuel quantity and timing is controlled throughout the total operating range to provide adequate torque and power.
An Engine Oil Temperature signal detected out of range, high or low, by the PCM will cause the PCM to substitute a temperature based on ECT to be used for operating purposes.
Exhaust Pressure Sensor
Exhaust Pressure (EP) Sensor:
The Exhaust Pressure (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 EP sensor signal is no longer used. The PCM utilizes the MAF and other temperature inputs to calculate exhaust pressure.
Fan Speed Sensor (FSS)
The fan speed sensor is a Hall-Effect sensor integral to the vistronic drive fan (VDF). The powertrain control module (PCM) will monitor the sensor input and control the VDF speed based upon engine coolant temperature (ECT), transmission fluid temperature (TFT) and intake air temperature (IAT) requirements. When an increase in fan speed for vehicle cooling is requested, the PCM will monitor the FSS signal and output the required pulse width modulated (PWM) signal to a fluid port valve within the VDF.
Injection Control Pressure Sensor
Injection Control Pressure (ICP) Sensor:
The Injection Control Pressure (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 sensor measures the oil pressure in the high pressure pump cover, and the PCM uses this information to determine injection control pressure. The ICP sensor along with the Injection Control Pressure Regulator form a closed loop fuel pressure control system.
If the PCM detects an inoperative ICP sensor, the PCM will control injection control pressure from a PCM-estimated injection control pressure.
Intake Air Temperature (IAT) Sensor
The intake air temperature (IAT) sensor is a thermistor device. The electrical resistance of a thermistor decreases as the temperature increases, and 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 utilizes two IAT sensors. The IAT sensor is integrated into the mass air flow (MAF) sensor. The powertrain control module (PCM) uses the IAT signal to control timing and fuel rate during cold starts and provide an input to the Cold Idle kicker.
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 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 powertrain control module (PCM).
Mass Air Flow Sensor
Mass Air Flow (MAF) Sensor:
Note: Moisture or other contamination of the MAF sensing element can cause incorrect ait flow input to the PCM resulting in EGR or VGT DTC's.
The mass air flow (MAF) sensor provides an analog voltage signal to the PCM proportional to the intake air mass. The MAF sensor utilizes 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 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 for exhaust pressure calculator and exhaust gas recirculation (EGR) diagnostics.
Output Shaft Speed Sensor
Output Shaft Speed (OSS) Sensor:
The Output Shaft Speed (OSS) sensor detects the speed of the transmission output shaft. The sensor uses variations in a magnetic field caused by a tone wheel to generate a pulse train output corresponding to shaft speed. The OSS sensor gear uses a repetitive pattern of three different angler displacements between teeth. The magnetic sensor element may be a Hall effect sensor or a 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 Signal Switch
The Parking Brake Signal switch indicates when the parking brake is applied. On F-250/550 and Excursion, the Parking Brake Signal switch is located under the instrument panel. The Parking Brake Signal switch will deactivate speed control if the brake is applied during speed control operation and provides a brake input for the Cold Idle kicker.
Power Monitor
The Diesel Engine Power Monitor (DEPM) strategy resides in the Transmission Control Module located inside of the PCM. The function of the DEPM is to monitor engine rpm when there is no power demand from the APP sensor.
Under normal engine idle operation, the DEPM value must always be higher than engine rpm. In the event that rpm does increase to its calibrated idle speed value following completion of deceleration fuel shutoff, due to the injectors not turning off, the DEPM will disable crank and cam output signals, sent by the PCM to the FICMM. The FICMM input line informs the DEPM when the injectors are turned on and when the injectors are turned off. When the FICMM line is either shorted or open, the monitor strategy assumes that the fuel injectors are always turned on and sets a DTC.
Speed Control Command Switches
The Speed Control Command switches are momentary switches which are located on the steering wheel. They consist of one ON-OFF switch and one SET/ACCEL-COAST-RESUME switch. These switches, when pressed, select one of several resistance values which is sent to the PCM to select speed control functions.
Transmission Tow/Haul Control Switch
Column-Shift Transmission Tow/Haul Control Switch:
The Transmission Tow/Haul Control switch signals the PCM with key power whenever the transmission tow/haul control switch is pressed. On vehicles with this feature, the tow/haul indicator illuminates (refer to Transmission and Drivetrain for more information and diagnostics) when the transmission tow/haul control switch is cycled to engage and disengage the tow/haul strategy. The operator of the vehicle controls the position of the transmission tow/haul control switch.
4x4 Low Switch
The 4x4 Low Switch sends a ground signal to the instrument cluster when in 4x4 low. This input is used to adjust the shift schedule.
Using Standard Corporate Protocol (SCP), the cluster provides a 4x4 status signal to the PCM.