IAT
I have been going thru info at my disposal and it gives signals to the ecm
Hope this helps
The Powertrain Control Module (PCM) stores information in Keep Alive Random Access Memory (RAM) (a memory integrated circuit chip) about vehicle operating conditions, and then uses this information to compensate for component variability. Keep Alive RAM remains powered when the vehicle key is off so that this information is not lost.
PURPOSE
The 7.3L Direct Injection (DI) diesel engine uses a glow plug system which preheats air in the combustion chamber to improve cold engine starting.
OPERATION
The glow plug system is electronically controlled by the powertrain control module. The Powertrain Control Module (PCM) energizes the glow plugs immediately after the key is placed in the ON position and then determines how long the glow plugs will be on according to the engine oil temperature and the barometric pressure. The required time for the glow plugs to be energized decreases as the engine oil temperature and barometric pressure increase.
The glow plugs are self-regulating, and the PCM controls relay ON time.
The PCM protects the glow plugs by energizing them for short durations if the battery voltage is abnormally high.
COMPONENTS
The system consists of eight glow plugs, the glow plug relay, PCM, Engine Oil Temperature (EOT) sensor and Barometric Pressure (BARO) sensor.
1997 Ford Truck F 250 2WD HD Pickup V8-7.3L DSL Turbo VIN F
Vehicle Level Powertrain Management Computers and Control Systems Description and Operation Diesel Electronic Engine Control (EEC) System Diesel PCM Inputs
Diesel PCM Inputs
AIR CONDITIONING PRESSURE SWITCH
The A/C Pressure Switch (ACPSW) is used for A/C system pressure control. The normally open medium pressure contacts close at a predetermined A/C head pressure. This grounds the ACPSW circuit input to the Powertrain Control Module (PCM) . The PCM will then turn on the high speed fan to help reduce the pressure.
BRAKE LAMP SWITCH
The Brake Lamp 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.
CAMSHAFT POSITION SENSOR
The PCM receives engine rotational position information from the Camshaft Position (CMP) sensor. The CMP is a hall-effect device. The target wheel spokes and spaces are each 15 crank degrees, except for narrow spoke which indicates cylinder No. 1 and a wide spoke which indicates cylinder No. 4 (fires 5th). The NGS PID RPM is generated by the PCM from the CMP signal.
CLUTCH PEDAL POSITION SWITCH
The Clutch Pedal Position (CPP) switch is an input to the PCM indicating the clutch pedal position. The CPP sends battery voltage to the PCM when the clutch is engaged (foot off pedal) and zero voltage when the clutch is disengaged (pedal depressed).
INTAKE AIR TEMPERATURE SENSOR
The Intake Air Temperature (IAT) signal provides air temperature information to the PCM. The PCM uses the air temperature information to operate the Exhaust Back Pressure (EBP) system.
TRANSMISSION CONTROL SWITCH
The Transmission Control Switch signals the PCM with keypower whenever the transmission control switch is pressed. On vehicles with this feature, the Transmission Control Indicator Lamp (TCIL) lights when the transmission control switch is cycled to disengage overdrive.
VEHICLE SPEED SENSOR
The PCM uses the frequency signal generated by the Vehicle Speed Sensor (VSS) (and other inputs) to control such parameters as fuel injection, ignition control, transmission/transaxle shift scheduling and torque converter clutch scheduling.
4x4 LOW SWITCH
The 4x4 Low Switch sends a ground signal to the PCM when in 4x4L. This input is used to adjust the shift schedule.
ACCELERATOR PEDAL SENSOR
The Accelerator Pedal (AP) sensor provides the PCM with the driver's demand for power. The AP sensor is a three-wire potentiometer that receives Reference Voltage (VREF) from the PCM and returns a signal to the PCM directly proportional to the accelerator pedal position. The AP signal is used in calculating fuel quantity and also to control the Exhaust Back Pressure Regulator (EPR) .
IDLE VALIDATION SWITCH
The Idle Validation Switch (IVS) verifies when the accelerator pedal is in the idle position. This switch protects against in-range failure of the AP sensor.
EXHAUST BACK-PRESSURE SENSOR
The exhaust back-pressure is controlled by the PCM to provide more heat to the coolant for cab heating when ambient air temperature is below 7°C (45°F) and engine oil temperature is below 75°C (167°F) during low load, low speed operating conditions.
INJECTION CONTROL PRESSURE SENSOR
The Injection Control Pressure (ICP) sensor measures the oil pressure in the LH injection rail. The PCM uses this information to determine injection control pressure. The Injection Control Pressure sensor along with the Injection Control Pressure Regulator form a closed loop fuel pressure control system.
ENGINE OIL TEMPERATURE SENSOR
The Engine Oil Temperature (EOT) signal is used by the PCM to calculate fuel quantity, injection timing, glow plug operation and exhaust back-pressure.
MANIFOLD ABSOLUTE PRESSURE SENSOR
The Manifold Absolute Pressure (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.
BAROMETRIC PRESSURE SENSOR
The Barometric Pressure (BARO) sensor is a variable capacitor sensor that is supplied a 5-volt reference signal by the PCM and returns a linear analog voltage signal which indicates atmospheric pressure. This allows the PCM to compensate for altitude. The PCM uses this information to calculate injection timing and glow plug control.
PARKING BRAKE SIGNAL SWITCH
The Parking Brake Signal switch indicates when the parking brake is applied. The Parking Brake Signal switch is located under the instrument panel. The Parking Brake Signal switch will deactivate speed control if the parking brake is applied during speed control operation.
BRAKE PRESSURE APPLIED SWITCH
The Brake Pressure Applied (BPA) switch is a hydraulically-actuated pressure switch that senses brake pressure and provides a back-up to the stoplight switch to deactivate speed control. The switch is totally independent (mechanically and electrically) from the brake lamp switch.
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.
INJECTOR DRIVER MODULE FEEDBACK
The Injector Driver Module (IDM) provides an Electronic Feedback (EF) signal to the PCM which confirms that proper timing/duration of the PCM command was received by the IDM. The EF signal is also used to send diagnostic information about the IDM and fuel injector circuitry.
