Ford F150 Pickup. Instruction - part 1646

Fig. 82: Identifying EGR System Module Components & Circuits (2 Of 2)
Courtesy of FORD MOTOR CO.

SELF-DIAGNOSTIC SYSTEM

MALFUNCTION INDICATOR LIGHT

Malfunction Indicator Light (MIL) alerts the driver that PCM has detected an OBD-II emission related
component or system fault. When this occurs, an OBD-II DTC will be set. MIL is located on instrument cluster
and is labeled CHECK ENGINE, SERVICE ENGINE SOON or uses an ISO standard engine symbol. See Fig.
83 . Power is supplied to MIL whenever ignition switch is in RUN or START position. MIL will remain ON in
RUN or START mode as a bulb check during instrument cluster proveout for about 4 seconds. MIL will remain
on after bulb check for the following reasons:

PCM illuminates MIL for an emission related concern and a DTC will be present.

Instrument cluster will illuminate MIL if PCM does not send a control message to instrument cluster.

PCM is operating in Hardware Limited Operation Strategy (HLOS). See HARDWARE LIMITED
OPERATION STRATEGY under POWERTRAIN CONTROL MODULE under COMPUTERIZED
ENGINE CONTROLS.

MIL circuit is shorted to ground.

If MIL remains off (during bulb check), possible causes are; bulb is damaged or MIL circuit is open. To turn off
the MIL after a repair, a reset command from scan tool must be sent, or 3 consecutive drive cycles must be
completed without a fault. If MIL blinks at a steady rate, a severe misfire condition could possibly exist. If MIL
blinks erratically, an intermittent open in B+ circuit to bulb or an intermittent short to ground in MIL circuit
may exist. Also, PCM can reset while cranking if battery voltage is low.

NOTE:

All systems have self-diagnostic capabilities. For information on procedures for
entering self-test modes and reading diagnostic trouble codes, see SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.

2003 Ford Pickup F150

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

Fig. 83: ISO Standard Engine Symbol
Courtesy of FORD MOTOR CO.

ELECTRONIC THROTTLE CONTROL

DESCRIPTION

Torque based Electronic Throttle Control (ETC) is a strategy that delivers a transmission output shaft torque
(via throttle angle) based on driver demand (pedal position). It utilizes the Visteon Gen II electronic throttle
body (replaces throttle cable). See Fig. 84 . Torque based ETC strategy was developed mainly to improve fuel
economy. This is possible by not coupling the throttle angle to pedal position, which enables various fuel
economy schemes and technologies.

Torque based ETC enables aggressive automatic transmission shift schedules (earlier upshifts and later
downshifts). This is possible by adjusting the throttle angle to achieve the same wheel torque during shifts. In
other words, the engine shifts can result is an engine lugging condition (low RPM and low manifold vacuum)
while still delivering the same torque requested by the driver. It should be noted that the ETC system includes a
wrench light on the instrument cluster that illuminates when a fault is detected. Faults are also accompanied by
DTCS and the "Check Engine Soon" light.

2003 Ford Pickup F150

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

It also enables many fuel economy/emission improvement technologies such as:

VCT (deliver same torque during transitions)

Continuously Varying Transmission (CVT)

Hybrid Electric Vehicle (HEV)

Torque based ECT also results is a less intrusive vehicle and engine speed limiting, along with smoother
traction control. Other generic benefits of ETC are:

Eliminate cruise control actuators

Eliminate ISC Bypass actuator

Better airflow range

Packaging (no cable)

ELECTRONIC THROTTLE BODY

The Gen II electronic throttle body has the following characteristics:

1. The DC motor is driven by the PCM (requires two wires). The gear ratio from the motor to the throttle

plate shaft is 17:1.

2. There are two designs; parallel and in-series. The parallel design has the motor under the bore parallel to

the plate shaft. The motor housing is integrated into the main housing (in general this is more difficult to
package). The in-series design has a separate motor housing that protrudes out and offers more packaging
flexibility.

3. Two springs are used: one is used to close the throttle (main spring) and the other is in a plunger

assembly that results in a default angle with no power applied. This is for limp home reasons (force of
plunger spring is 2X main spring). Default angle is usually set to result in a top vehicle speed of 30 MPH
(typically 7 to 8 degrees from hard-stop angle).

4. The closed throttle plate hard stop is used to avoid the throttle from binding is the bore (about 0.75

degree). This hard stop is non-adjustable and is set to result in less airflow than the minimum engine
airflow required at idle.

5. Unlike cable type throttle bodies, the intent for the ETB is not to have a hole in the plate or use plate

sealant. The hole in the plate is not required with ETB because the required idle airflow is provided by the
plate angle, which also is the reason there is no IAC.

6. The system has two throttle position sensors. Redundant throttle position signals are required for monitor

reasons. TP1 has a negative slope (increasing angle, decreasing voltage) and TP2 has a positive slope
(increasing angle, increasing voltage). During normal operation the negative sloped TP sensor (TP1) is
used by the control strategy as the indication of throttle position. The TP assembly requires four wires:

5 V Reference Voltage

Signal Return (ground)

TP1 voltage with negative voltage slope (5-0)

TP2 voltage with positive voltage slope (0-5)

2003 Ford Pickup F150

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

ACCELERATOR PEDAL POSITION SENSORS

The ETC strategy uses pedal position sensors as an input to determine the driver demand.

1. There are three pedal position sensors required for safety monitor reasons. APP1 has a negative slope

(increasing angle, decreasing voltage) and APP2 & APP3 both have a positive slope (increasing angle,
increasing voltage). During normal operation APP1 is used as the indication of pedal position by the
strategy.

2. There are two VREF wires, two signal return wires and three signal wires (total of seven wires and pins)

between the PCM and APPS assembly.

2-5 V Reference Voltage.

2-Signal Return "ground".

APP1 voltage with negative voltage slope (5-0).

APP2 voltage with positive voltage slope (0-5).

APP3 voltage with positive voltage slope (0-5).

3. The pedal position signal is converted to pedal travel degrees (rotary angle) by the PCM. The software

then converts these degrees to counts, which is the input to the torque based strategy.

4. The three pedal position signals ensure a correct input to the PCM, if any one signal has a fault. The PCM

knows if a signal is wrong by calculating where it should be, inferred by the other signals. A safe value
will be substituted for a faulty signal if two out of the three signals are bad.

Fig. 84: Identifying Electronic Throttle Control Components
Courtesy of FORD MOTOR CO.

MISCELLANEOUS CONTROLS

2003 Ford Pickup F150

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

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