PCM Outputs

NOTE: Transmission outputs which are not described here are discussed at Transmission System.

Canister Vent Solenoid
For information on the canister vent solenoid, refer to the description of the Evaporative Emission System.

Coil Pack

Six-Tower Coil Pack:

A coil in a coil pack (Figure 49) is turned on (for example is coil charging) by the Powertrain Control Module (PCM), and is turned off when firing two spark plugs at once. The spark plugs are paired so that as one spark plug fires on the compression stroke, the other spark plug fires on the exhaust stroke. The next time the coil is fired the order is reversed. The next pair of spark plugs fire according to the engine firing order.

Coil On Plug

Coil On Plug:

The Coil On Plug (COP) (Figure 50) ignition operates similar to standard coil pack ignition except each plug has one coil per plug. COP has three different modes of operation: engine crank, engine running, and CMP Failure Mode Effects Management (FMEM).

Engine Crank/Engine Running
During engine crank the PCM will fire two spark plugs simultaneously. Of the two plugs simultaneously fired one will be under compression the other will be on the exhaust stroke. Both plugs will fire until camshaft position is identified by a successful camshaft position sensor signal. Once camshaft position is identified, only the cylinder under compression will be fired.

CMP FMEM
During CMP FMEM the COP ignition works the same as during engine crank. This allows the engine to operate without the PCM knowing if cylinder one is under compression or exhaust.

Electric Motor EGR System (EEGR)
For information on the EEGR system, refer to the description and operation section. Electric Exhaust Gas Recirculation (EEGR) System Monitor.

EGR System Module (ESM)
For information on the ESM system, refer to the description and operation section. Electric Exhaust Gas Recirculation (EEGR) System Monitor.

EGR Vacuum Regulator Solenoid
For information on the EGR Vacuum Regulator (EVR) solenoid, refer to the description of the Exhaust Gas Recirculation Systems.

Electric Secondary Air Injection Pump
For information on the electric secondary air injection pump, refer to the description of the Secondary Air Injection Systems.

Evaporative Emission Canister Purge Valve
For information on the Evaporative Emission (EVAP) canister purge valve, refer to the description of the Evaporative Emission Systems.

Fan Control

Crown Victoria/Grand Marquis, Town Car: FCV Duty Cycle Output From PCM (negative Duty Cycle):

LS6/LS8, Thunderbird: FCV Duty Cycle Output From PCM, Part 1:

LS6/LS8, Thunderbird: FCV Duty Cycle Output From PCM, Part 2:

The PCM monitors certain parameters (such as engine coolant temperature, vehicle speed, A/C on/off status, A/C pressure, etc) to determine engine cooling fan needs.

For Variable Speed Electric Fan(s):
The PCM controls the fan speed and operation using a duty cycle output on the Fan Control - Variable (FCV) circuit. The fan controller (located at or integral to the engine cooling fan assembly) receives the FCV command and operates the cooling fan at the speed requested (by varying the power applied to the fan motor).

For Relay Controlled Fans:
The PCM controls the fan operation through the Fan Control (FC) (single speed fan applications), Low Fan Control (LFC), Medium Fan Control (MFC) and/or High Fan Control (HFC) outputs.

2.0L Focus (With A/C) And Taurus/Sable: PCM FC Output State For Cooling Fan Speeds Chart:

ESCAPE: PCM FC Output State For Cooling Fan Speeds Chart:

For three speed fans, although the PCM output circuits are called low, medium and high fan control (FC), cooling fan speed is controlled by a combination of these outputs. Refer to the table.

Fuel Cap Off Indicator Lamp
The Fuel Cap Off Indicator Lamp (FCIL) is an output signal that is controlled by the PCM and will illuminate when the strategy determines that there is a failure in the vapor management system due to the fuel filler cap not being sealed properly. This would be detected by the inability to pull vacuum in the fuel tank, after a fueling event.

NOTE: The Escape, Windstar, Mustang, Thunderbird, Town Car, Lincoln LS6/LS8, Expedition and Navigator do not have a dedicated (separate) output wire from the PCM to the instrument cluster. The PCM commands the FCIL on and off through the BUS +/- circuits (SCP).

Fuel Pump

Applications Using a Fuel Pump Relay for Fuel Pump On/Off Control

The Fuel Pump (FP) is a PCM output signal that is used to control the electric fuel pump. With the electronic EC power relay contacts closed, Vehicle Power (VPWR) is sent to the coil of the fuel pump relay. For electric fuel pump operation, the PCM grounds the FP circuit, which is connected to the coil of the fuel pump relay. This energizes the coil and closes the contacts of the relay, sending B+ through the FP PWR circuit to the electric fuel pump. When the ignition key is turned on, the electric fuel pump runs for about one second, but is then turned off by the PCM if engine rotation is not detected.

Low Speed Fuel Pump Relay Wiring:

For applications with two speed fuel pumps, a normally closed low speed fuel pump relay (Figure 51) is wired into the fuel pump ground circuit. With the low speed fuel pump relay contacts in the normally closed position, there is no extra resistance in the ground circuit for high speed operation. For low speed fuel pump operation, the PCM will ground the Low Fuel Pump (LFP) circuit, which opens the relay contacts. With the relay contacts open, the fuel pump ground circuit now passes through a resistor that is wired into the circuit.

Fuel Pump Driver Module Applications (and Applications with Fuel Pump Functions Incorporated in Rear Electronic Module)

NOTE: For the Thunderbird and LS6/LS8, the Fuel Pump Driver Module (FPDM) functions are incorporated in the Rear Electronic Module (REM). Fuel pump operation is the same as applications using the stand-alone FPDM. The REM will, however, communicate diagnostic information through the BUS +/- circuits (SCP) instead of using a Fuel Pump Monitor (FPM) circuit.

Fuel Pump Duty Cycle Output From PCM Chart:

The Fuel Pump (FP) signal is a duty cycle command sent from the powertrain control module (PCM) to the fuel pump driver module (FPDM) (Table 2). The FPDM uses the FP command to operate the fuel pump at the speed requested by the PCM or to turn the pump off.

Fuel Injectors
For information on the fuel injectors, refer to the description of the Fuel Systems.

Fuel Pressure Regulator Control Solenoid
For information on the Fuel Pressure Regulator Control (FPRC) solenoid, refer to the description of the Fuel Systems.

Generator Communication (Gen Corn)
For information on the generator (Gen Com), refer to the description of PCM/Controlled Charging System.

High Fan Control
For information on high fan control, refer to Fan Control.

Idle Air Control Solenoid
For information on the idle air control solenoid, refer to the description of the Intake Air Systems.

Intake Manifold Runner Control
For information on the intake manifold runner control, refer to the description of the Intake Air Systems.

Intake Manifold Swirl Control
For information on the intake manifold swirl control, refer to the description of the Intake Air Systems.

Intake Manifold Tuning Valve
For information on the intake manifold tuning valve, refer to the description of the Intake Air Systems.

Low Fan Control
For information on low fan control, refer to Fan Control.

Medium Fan Control
For information on medium fan control, refer to Fan Control.

Secondary Air Injection Bypass Solenoid
For information on the secondary air injection bypass solenoid, refer to the description of the Secondary Air Injection Systems.

Thermostat Heater Control

Thermostat Assembly With Heater Control:

The primary objective for the thermostat heater control is for improvement in fuel economy and thermal efficiency. The system consists of a high temperature (98°C/208°F in lieu of a 90°C/194°F) thermostat (Figure 52) that has a resistive heater within the wax element. The heater is controlled by the PCM dependent on engine speed, throttle position, engine load, barometric pressure, air charge temperature, transmission oil temperature and engine coolant temperature.

During low speed, low load and low air charge temperature conditions, the thermostat heater is OFF and the engine is allowed to operate at an elevated coolant temperature. This should result in lower internal friction and higher thermal efficiency, both leading to improved fuel economy.

During high speed, high load, high temperature conditions (air charge, transmission oil or engine coolant), the PCM output is energized with a duty cycle to the thermostat heater. This heats the wax and forces the thermostat to rapidly open wider allowing extra coolant to flow from the radiator. This will reduce the coolant temperature and improve with performance demand.

It should be noted that the heater is only capable of supplying a SMALL amount of additional heat to the wax element; it is NOT capable of opening the thermostat alone. The thermostat is 100% duty cycle for short calibrated time and than the duty cycle is reduce to a maximum of 70% on and 30% off.

Approximately, unheated, the thermostat will begin to open at a coolant temperature of 98°C (208°F) and will be fully open at approx. 108°C (226°F). Energizing the heater will reduce the opening temperature to about 68°C (154°F) and the fully open temperature to 103°C (217°F).

Transmission Control Indicator Lamp
The Transmission Control Indicator Lamp (TCIL) is an output signal from the PCM that controls the lamp on/off function depending on the engagement or disengagement of overdrive. Refer to Transmission Control Switch in Hardware PCM Inputs.

Wide Open Throttle A/C Cut-Off (WAC)
The wide open throttle A/C cutoff relay (may be referred to as the A/C clutch relay) is wired normally open (normally closed for Aviator). There is no direct electrical connection between the A/C switch or EATC Module and the A/C clutch. The PCM will receive a signal indicating that A/C is requested (for some applications, this message is sent through the BUS + and BUS - circuits). When A/C is requested, the PCM will check other A/C related inputs that are available (such as ACP (SW), ACCS). If these inputs indicate A/C operation is OK, and the engine conditions are OK (such as coolant temperature, engine rpm, throttle position), the PCM will ground the WAC output (unground for Aviator), closing the relay contacts and sending voltage to the A/C clutch.

Vapor Management Valve (VMV)
For information on the vapor management valve (EVAP canister purge valve), refer to the description of the Evaporative Emission Systems.

Visctronic Drive Fan (VDF)

Visctronic Drive Fan (VDF) Clutch:

The primary purpose for the Visctronic Drive Fan (VDF) (Figure 53) clutch is to optimize fan energy (i.e. improved fuel economy) while meeting cooling performance requirements. Successful optimization will also minimize objectionable fan noise. The operation is similar to the existing viscous fan clutch, except viscous fluid flow is controlled by a Pulse Width Modulated (PWM) solenoid versus a bi-metal temperature sensor on the front of the clutch.

The VDF consists of three main elements, a working chamber, a reservoir chamber, and a Fan Speed Sensor (FANSS). A fluid port valve controls fluid flow from the reservoir into the working chamber. Once viscous fluid is in the working chamber, "shearing" of the fan clutch fluid will result in fan rotation. The valve is activated via a pulse width modulated (PWM) output signal from the PCM. By opening and closing the fluid port valve, the PCM can control approximate fan speed. Fan speed is monitored via a Hall-Effect sensor and is read by the PCM for closed loop operation.

The PCM will optimize the VDF fan speed based upon CHT, TFT, or IAT cooling requirements. When either of these inputs is demanding increased fan speed for vehicle cooling, the PCM will monitor the Hall Effect Fan Speed Sensor (FAN SS), and output the resultant PWM signal to the fluid port valve thus controlling to the required fan speed.

Powertrain Control Module - Vehicle Speed Output (VSO)
The PCM-VSO (Powertrain Control Module - Vehicle Speed Output) speed signal subsystem generates vehicle speed information for distribution to the vehicle's 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 hard-wired signal or as a multiplexed data message.

The key features of the PCM-VSO system are to:
^ Infer vehicle movement from the output shaft sensor signal
^ Convert transmission output shaft rotational information to vehicle speed information
^ Compensate for tire size and axle ratio with a programmed calibration variable
^ Utilize a transfer case sensor for four wheel drive applications
^ Distribute vehicle speed information as a multiplexed message and/or an analog signal

The signal from a non-contact shaft sensor (Output Shaft Sensor--OSS or Transfer Case Shaft Sensor--TCSS) mounted on the transmission (automatics, manuals, or 4X4 transfer cases) is sensed directly by the PCM. The PCM converts the OSS or TCSS information to 8000 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 the vehicle speed signal users on the vehicle. VSO information can be transmitted by a hard-wired interface between the vehicle speed signal user and the PCM, or by Speed and Odometer SCP multiplexed data messages.

The VSO hard-wired signal wave form is a DC square wave with a voltage level of 0 to VBAT. Typical output operating range is 2.22 Hz per MPH (1.3808 Hz pr 1 Km/h). Multiplexed data for speed and distance data are transmitted as separate SCP messages over the SCP multiplex link.