Ford F150 Pickup. Instruction — part 1624

Fig. 18: Identifying Hall Effect Camshaft Position Sensor
Courtesy of FORD MOTOR CO.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline

Fig. 19: Identifying Variable Reluctance Camshaft Position Sensor
Courtesy of FORD MOTOR CO.

Clutch Pedal Position Switch

Clutch Pedal Position (CPP) switch is mounted near clutch pedal. CPP switch is an input for Powertrain Control
Module (PCM) indicating clutch pedal position and, in some instruction transmission applications, both clutch
pedal position and gearshift position. PCM provides a 5-volt reference (VREF) signal to CPP and/or
Park/Neutral Position (PNP) switch (on CPP signal circuit). If CPP switch is closed (indicating clutch pedal
applied) and shift lever is in Neutral position, output voltage from PCM is grounded through signal return
circuit to PCM and one volt or less will be present. If CPP switch (or PNP switch, or both CPP and PNP
switches) is open, meaning clutch pedal is released (all systems), or shift lever is not in Neutral position (PNP
switch systems), CPP input signal to PCM will be about 5 volts, indicating a load on engine. PCM uses load
information for mass airflow and fuel calculations.

Crankshaft Position Sensor

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline

Crankshaft Position (CKP) sensor is a magnetic transducer mounted on engine block, next to crankshaft pulse
wheel. On all engines except 6.8L, trigger wheel has a total of 35 teeth spaced 10 degrees apart with one empty
space for a missing tooth. On 6.8L, trigger wheel has a total of 39 teeth spaced 9 degrees apart and one 9 degree
empty space for a missing tooth. By monitoring pulse wheel, CKP sensor indicates crankshaft position and
speed information to PCM. By monitoring missing tooth, CKP sensor is also able to identify piston travel to
synchronize ignition system and provide a way of tracking angular position of crankshaft relative to a fixed
reference.

Cylinder Head Temperature Sensor

Cylinder Head Temperature (CHT) sensor is mounted in an aluminum cylinder head and measures metal
temperature. CHT sensor is a thermistor which changes resistance proportionate to temperature changes.
Resistance increases as cylinder head temperature decreases and decreases as cylinder head temperature
increases. Thermistor type sensors are considered passive sensors. A passive sensor is connected to a voltage
divider network so that varying resistance of passive sensor causes a variation in total current flow.

Voltage that is dropped across a fixed resistor in series with sensor resistor determines voltage signal at PCM.
This voltage signal is equal to reference voltage minus the voltage drop across the fixed resistor. If CHT sensor
signal indicates an overheating condition, PCM will initiate a fail-safe cooling strategy based on information
from CHT sensor. For additional information, see FAIL-SAFE COOLING STRATEGY under
POWERTRAIN CONTROL SOFTWARE. Using both CHT sensor and fail-safe cooling, PCM prevents
damage by allowing air cooling of engine and limp home capability.

Differential Pressure Feedback EGR Sensor

See DIFFERENTIAL PRESSURE FEEDBACK EGR SYSTEM under EGR SYSTEMS.

Engine Coolant Temperature Sensor

Engine Coolant Temperature (ECT) sensor is a thermistor device in which resistance changes with temperature.
Electrical resistance of a thermistor decreases as temperature increases, and increases as temperature decreases.
Varying resistance affects voltage drop across sensor terminals and provides electrical signals to PCM
corresponding to temperature. Thermistor type sensors are considered passive sensors. A passive sensor is
connected to a voltage divider network so that varying resistance of passive sensor causes a variation in total
current flow. Voltage that is dropped across a fixed resistor in a series with sensor resistor determines voltage
signal at PCM. This voltage signal is equal to reference voltage minus voltage drop across fixed resistor. ECT
measures temperature of engine coolant and is threaded into an engine coolant passage. ECT sensor is similar in
construction to IAT sensor.

Engine Fuel Temperature Sensor

Engine Fuel Temperature (EFT) sensor inputs fuel temperature of fuel near fuel injectors to the PCM. EFT
sensor is a thermistor device which changes resistance proportionate to temperature changes. Resistance
increases as fuel temperature decreases and decreases as fuel temperature increases. Signal is used by PCM to
adjust fuel injector pulse width and meter fuel to each cylinder.

Engine Oil Temperature Sensor

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline

The Engine Oil Temperature (EOT) 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.

Thermistor-type sensors are considered passive sensors. A passive sensor is connected to a voltage divider
network so that varying the resistance of the passive sensor causes a variation in total current flow. Voltage that
is dropped across a fixed resistor in a series with the sensor resistor determines the voltage signal at the PCM.
This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.

The EOT sensor measures the temperature of the engine oil. The sensor is typically threaded into the engine oil
lubrication system near the oil filter. The PCM can use the EOT sensor input to determine the following:

z

On Variable Cam Timing (VCT) applications the EOT input is used to adjust the VCT control gains and
logic for camshaft timing.

z

The PCM can use EOT sensor input in conjunction with other PCM inputs to determine oil degradation.

z

The PCM can use EOT sensor input to initiate a soft engine shutdown. To prevent engine damage from
occurring as a result of high oil temperatures, the PCM has the ability to initiate a soft engine shutdown.
Whenever engine RPM exceeds a calibrated level for a certain period of time, the PCM will begin
reducing power by disabling engine cylinders.

Fan Speed Sensor

See VISTRONIC DRIVE FAN under OUTPUT SIGNALS.

Fuel Level Input

Fuel Level Input (FLI) is a hard wire signal input to PCM from Fuel Pump (FP) module. See description of FLI
under ENHANCED EVAPORATIVE EMISSION SYSTEM under EVAPORATIVE EMISSION
SYSTEMS.

Fuel Pump Monitor (With Fuel Pump Driver Module)

Fuel Pump Driver Module (FPDM) communicates diagnostic information to PCM through Fuel Pump Monitor
(FPM) circuit. This information is sent by FPDM as a duty cycle signal. The 3 duty cycle signals that may be
sent are listed in FUEL PUMP DRIVER MODULE DUTY CYCLE SIGNALS table. PCM uses this signal
to verify FPDM is powered and able to communicate on the FPM circuit.

FUEL PUMP DRIVER MODULE DUTY CYCLE SIGNALS

Duty Cycle
Percent

(1)

On Time

(ms)

Comments

(2)

FP_M

PID

25

250

(3)

FPDM Did Not Receive Fuel Pump (FP) Duty Cycle

Command From PCM, Or Duty Cycle Received Was Invalid

15-60

50

500

"All Ok" Output From FPDM. With This Input, PCM Can Verify

FPDM Is Powered And Able To Communicate On FPM Circuit

80-125

75

750

FPDM Has Detected Fault In Circuits Between Fuel Pump And

250-400

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline