Ford F150 Pickup. Instruction — part 1627

Fig. 24: Identifying Thermal Manifold Absolute Pressure Sensor
Courtesy of FORD MOTOR CO.

Throttle Position Sensor

Throttle Position (TP) sensor is a rotary potentiometer sensor that provides a signal to PCM that is linearly
proportional to throttle plate/shaft position. TP sensor housing has a 3-blade electrical connector that may be
gold plated. The gold plating increases corrosion resistance on terminals and increases connector durability. TP

2003 Ford Pickup F150

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

sensor is mounted on throttle body and has 4 operating conditions: closed throttle (idle or deceleration), part
throttle (cruise or moderate acceleration), wide open throttle (includes maximum acceleration or de-choke on
crank), and throttle angle rate. TP sensor signal affects air/fuel ratio, injector timing, idle speed, EGR flow and
ignition timing.

Transmission Control Switch

Transmission Control Switch (TCS) may also be referred to as overdrive (O/D) cancel switch. The TCS signals
the PCM with keypower whenever the TCS is pressed. TCS position is controlled by vehicle operator. If
overdrive is disengaged, O/D OFF indicator located on instrument panel, or Transmission Control Indicator
Light (TCIL) located on shift lever, will illuminate.

Vehicle Speed Sensor

Vehicle Speed Sensor (VSS) is a variable reluctance or Hall Effect type sensor that generates a waveform with a
frequency that is proportional to vehicle speed. When vehicle is moving slowly, sensor produces a low
frequency signal. As vehicle speed increases, sensor produces a higher frequency signal. PCM uses this signal
to control fuel injection, ignition timing and transaxle/transmission shift and Torque Converter Clutch (TCC)
scheduling.

4x4 Mode Switch

Generic Electronic Module (GEM) provides PCM with an indication of 4x4L. This input is used to adjust
transmission shift scheduling. A 5-volt module pull-up indicates 4x4H or 2WD. See Fig. 25 .

2003 Ford Pickup F150

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

Fig. 25: Identifying 4x4 Mode Switch
Courtesy of FORD MOTOR CO.

2003 Ford Pickup F150

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

OUTPUT DEVICES

Vehicles are equipped with different combinations of computer controlled components. Not all components
listed are used on every vehicle. For theory and operation on each output component, refer to system indicated
after component.

Canister Vent Solenoid

See FUEL EVAPORATIVE SYSTEM under EVAPORATIVE EMISSION SYSTEMS.

Coil Pack

A coil in a coil pack is turned on (coil charging) by PCM, and is turned off when 2 spark plugs are fired
simultaneously. Spark plugs are paired so that one spark plug fires on the compression stroke and other spark
plug fires on exhaust stroke. Next time coil is fired, order is reversed and next pair of spark plugs fire according
to engine firing order.

Coil On Plug

Coil On Plug (COP) ignition operates similar to a standard coil pack ignition except each spark plug has one
coil per spark plug. See Fig. 26 . COP has 3 different modes of operation:

z

Engine Cranking

During engine cranking, PCM will fire 2 spark plugs simultaneously. One spark plug will fire on
compression stroke and the other spark plug fires on exhaust stroke. Both spark plugs will fire until
camshaft position is identified by a successful camshaft sensor signal.

z

Engine Running

Once camshaft position is identified and engine is running, only spark plug with cylinder under
compression will be fired.

z

CMP Failure Mode Effects Management (CMP FMEM)

During CMP FMEM, COP ignition operates similar to engine cranking mode. This allows engine to
operate without requiring PCM to know if cylinder is on compression or exhaust stroke.

NOTE:

Transmission related PCM outputs are not listed here. For a complete listing of
transmission related PCM inputs, see appropriate DIAGNOSIS article in
AUTOMATIC TRANSMISSIONS.

2003 Ford Pickup F150

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