Operation CHARM: Car repair manuals for everyone.
Home >> Lincoln >> 2011 >> MKZ FWD V6-3.5L >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Description and Operation >> Powertrain Control Hardware

Powertrain Control Hardware

POWERTRAIN CONTROL HARDWARE

Powertrain Control Module (PCM)
The center of the engine control (EC) system is a microprocessor called the PCM. The PCM receives input from sensors and other electronic components (switches, relays). Based on the information received and programmed into its memory, the PCM generates output signals to control various relays, solenoids and actuators. There are several different types of PCMs in use for this model year. Refer to the Vehicle PCM Application Table below for PCM types and their applications.







PCM Locations
For PCM removal and installation procedures, refer to the Computers and Control Systems, Electronic Engine Controls.
- Crown Victoria, Grand Marquis, Town Car - engine compartment, driver side, fender mounted.
- E-Series - engine compartment, driver side, near the cowl (access from the engine compartment).
- Edge, Expedition, F-150, F-Series Super Duty, MKX, Navigator - passenger side of the engine compartment, mounted to the cowl.
- Explorer - engine compartment, center position, mounted to the cowl under the cowl panel grille.
- Fiesta - engine compartment, driver side, near the battery.
- Flex, MKS, MKT, Taurus - engine compartment, passenger side, mounted to the cowl under the cowl panel grille.
- Focus, Transit Connect - engine compartment, driver side, front of battery.
- Fusion, Milan, MKZ - engine compartment, driver side, under battery, mounted to the cowl.
- Mustang - front of engine compartment, passenger side, near the battery junction box (BJB).



























Fuel Pump Control Module

NOTE: The Mustang 5.4L uses 2 fuel pump control modules to control fuel for the fuel delivery system. The PCM outputs only one fuel pump duty cycle on the fuel pump control (FPC) circuit. Both fuel pump control modules use this circuit. The PCM individually monitors the fuel pump control modules through the FPM and FPM2 circuits. The fuel pump control module located on the driver side of the luggage compartment is referred to as Fuel Pump Control Module 1 and the fuel pump control module located on the passenger side of the luggage compartment, is referred to as Fuel Pump Control Module 2.

The fuel pump control module receives a duty cycle signal from the PCM and controls the fuel pump operation in relation to this duty cycle. The PCM requests low or high speed fuel pump operation depending on engine fuel demand. The fuel pump control module controls the fuel pump by switching the fuel pump power circuit ON and OFF at the required duty cycle. The fuel pump control module sends diagnostic information to the PCM on the fuel pump monitor (FPM) circuit. For additional information on the fuel pump control and the fuel pump monitor, refer to Fuel Systems.

On vehicles with gasoline direct fuel injection, the high pressure fuel system may be under vacuum after several hours of cold soak. Fuel vapor may collect at the fuel injection pump, causing a long start condition. To prevent this, the fuel pump relay is energized for 1 or 2 seconds, depending on application, as soon as the dome light is commanded ON. This causes the fuel pump control module and the fuel pump to cycle for 1 or 2 seconds and purge any trapped air or fuel vapor from the high pressure fuel system.

Fuel Pump Driver Module (FPDM)
The FPDM receives a duty cycle signal from the PCM and controls the fuel pump operation in relation to this duty cycle. This results in variable speed fuel pump operation. The FPDM controls the fuel pump by switching the fuel pump return circuit ON and OFF at the required duty cycle. The FPDM sends diagnostic information to the PCM on the FPM circuit. For additional information on the fuel pump control and the fuel pump monitor, refer to Fuel Systems.

Keep Alive Memory (KAM)
The PCM stores information about vehicle operating conditions in the KAM (a memory integrated circuit chip) and then uses this information to compensate for component variability. The KAM remains powered when the ignition is in the OFF position so the information is not lost.

Power and Ground Signals

Accelerator Pedal Position Reference Voltage (APPVREF2) - Fiesta
APPVREF2 is a consistent positive voltage (5 volts plus or minus 0.5 volt) supplied by the instrument panel cluster (IPC). APPVREF2 is dedicated to the APP2 sensor.

Accelerator Pedal Position Reference Voltage (APPVREF) - All Others
APPVREF is a consistent positive voltage (5 volts plus or minus 0.5 volt) supplied by the PCM. APPVREF is internally bussed within the PCM and is dedicated to the APP sensor.

Accelerator Pedal Position Return (APPRTN2) - Fiesta
APPRTN2 is a return path for APPVREF2 supplied by the (IPC). APPRTN2 is dedicated to the APP2 sensor.

Accelerator Pedal Position Return (APPRTN) - All Others
APPRTN is a return path for APPVREF and is internally bussed within the PCM. APPRTN is dedicated to the APP sensor.

Electronic Throttle Control Reference Voltage (ETCREF)
ETCREF is a consistent positive voltage (5 volts plus or minus 0.5 volt) supplied by the PCM. ETCREF is internally bussed within the PCM and is dedicated to the electronic throttle body throttle position sensor (ETBTPS).

Electronic Throttle Control Return (ETCRTN)
ETCRTN is a return path for ETCREF and is internally bussed within the PCM. ETCRTN is dedicated to the electronic throttle body throttle position sensor (ETBTPS).

Gold Plated Pins

NOTE: Gold plated terminals should only be replaced with new gold plated terminals.

Some engine control hardware has gold plated pins within the connectors and mating harness connectors to improve electrical stability for low current draw circuits and to enhance corrosion resistance. The engine control (EC) components equipped with gold terminals vary by vehicle application.

Keep Alive Power (KAPWR)
KAPWR provides a constant voltage input independent of ignition switch state to the PCM. This voltage is used by the PCM to maintain the KAM.

Mass Airflow Return (MAF RTN)
The MAF RTN is a dedicated analog signal return from the MAF sensor. It serves as a ground offset for the analog voltage differential input by the MAF sensor to the PCM.

Power Ground (PWRGND)
The PWRGND circuit(s) is connected directly to the battery negative (B-) terminal. PWRGND provides a return path for the PCM vehicle power (VPWR) circuits.

Signal Return (SIGRTN)
SIGRTN is a dedicated return path for VREF applied components.

Starter Motor Request (SMR) Circuit
The SMR circuit provides the PCM with a signal from the ignition switch to the PCM. The input is pulled high when the ignition is in the START position and the transmission range sensor ignition lockout circuit allows the starter to engage.

Variable Reluctance Sensor Return (VRSRTN)
The VRSRTN circuit is a dedicated return path for variable reluctance (VR) type sensors.

Vehicle Buffered Power (VBPWR)
VBPWR is a regulated voltage supplied by the PCM to vehicle sensors. These sensors require a constant 12 volts for operation and cannot withstand VPWR voltage variations. VBPWR is regulated to VPWR minus 1.5 volts and is also current limited to protect the sensors.

Vehicle Power (VPWR)
VPWR is the primary source of PCM power. VPWR is switched through the PCM power relay and is controlled by the ignition switch.

Vehicle Reference Voltage (VREF)
VREF is a consistent positive voltage (5 volts plus or minus 0.5 volt) provided by the PCM. VREF is typically used by 3-wire sensors and some digital input signals.

Powertrain Control Module - Vehicle Speed Output (PCM-VSO)
The PCM-VSO speed signal subsystem generates vehicle speed information for distribution to those electrical/electronic modules and subsystems that require vehicle speed data. This subsystem senses the transmission output shaft speed with a sensor. The data is processed by the PCM and distributed as a hardwired signal or as a message on the vehicle communication network.

The key features of the PCM-VSO system are to:
- infer vehicle movement from the OSS sensor signal.
- convert transmission output shaft rotational information to vehicle speed information.
- compensate for tire size and axle ratio with a programmed calibration variable.
- use a transfer case speed sensor (TCSS) for four wheel drive (4WD) applications.
- distribute vehicle speed information as a multiplexed message and/or an analog signal.

The signal from a non-contact shaft sensor, such as an OSS or TCSS, mounted on the transmission (automatic, manual, or 4WD transfer case) is sensed directly by the PCM. The PCM converts the OSS or TCSS information to 8,000 pulses per mile, based on a tire and axle ratio conversion factor. This conversion factor is programmed into the PCM at the time the vehicle is assembled and can be reprogrammed in the field for servicing changes in the tire size and axle ratio. The PCM transmits the computed vehicle speed and distance traveled information to all vehicle speed signal users on the vehicle. VSO information can be transmitted by a hardwired interface between the vehicle speed signal user and the PCM, or by a speed and odometer data message through the vehicle communication network data link.

The PCM-VSO hardwired signal waveform is a DC square wave with a voltage level of 0 to VBAT. Typical output operating range is 1.3808 Hz per 1 km/h (2.22 Hz per mph).
pro multis · About Operation CHARM