PCM Outputs

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

Example: Six-Tower Coil Pack:

Coil Pack
A coil in a coil pack is turned ON (for example is coil charging) by the 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) 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.

Engine Cooling Fan Control







CCRM Applications: 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. The PCM controls the fan operation through the Fan Control (FC) output (single speed fan applications) or the Low Fan Control (LFC) and High Fan Control (HFC) outputs. Although the fan control, low speed fan control and high speed fan control relays are normally open relays, the FC/LFC circuit is wired through a voltage inverter inside the CCRM. The voltage inverter ensures that the PCM must turn ON (ground) the FC/LFC output to turn the fan OFF. This is done so the cooling fan will operate in the event of an open FC/LFC circuit.







Stand-Alone Fan Control Relay Applications: 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. The PCM determines engine cooling fan control requirements and controls the fan operation through the Low Fan Control (LFC) and High Fan Control (HFC) outputs.


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.

Fuel Pump

Low Speed Fuel Pump Relay Wiring:

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.

For applications with two speed fuel pumps, a normally closed low speed fuel pump relay 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): The Fuel Pump signal is a duty cycle command sent from the powertrain control module to the Fuel Pump Driver Module (FPDM). 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 Com)
For information on the Generator (Gen Com), refer to the description of PCM/Controlled Charging System.

Idle Air Control Solenoid
For information on the idle air control solenoid, 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.

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

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

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

Solid State Relay
For information on the solid state relay, refer to the description of the Secondary Air Injection Systems.

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

Contour/Mystique/Cougar (W/O Returnless Fuel System) and Mustang: The Wide Open Throttle Air Conditioning Cut-off (WAC) output is used by the PCM to disengage the A/C clutch when A/C compressor operation is not desirable. Under normal conditions, with the A/C OFF, the PCM will ground the WAC output, which opens the normally closed WOT A/C cut-off relay (this relay may be inside the constant control relay module). When the A/C demand switch is turned on, and the A/C cycling switch and A/C high pressure switch high pressure contacts are closed, voltage is supplied to the WOT A/C cut-off relay contacts and to the ACCS circuit. The voltage on the ACCS circuit indicates to the PCM that A/C is requested. The PCM will then verify that A/C clutch operation is desirable (for example, engine not cranking, overheated or not at WOT). If A/C clutch operation is desirable, the PCM will adjust idle speed as necessary and "unground" the WAC output. This closes the normally closed WOT A/C cut-off relay and for all vehicles except Contour/Mystique/Cougar, allows voltage to be supplied to the A/C clutch. For Contour/Mystique/Cougar, when the WOT A/C cut-off relay contacts are closed voltage is supplied to the A/C clutch relay. This will close the normally open contacts of the A/C clutch relay and allow voltage to be supplied to the A/C clutch.

All Others: For these applications, the wide open throttle A/C cutoff relay (may be referred to as the A/C relay) is normally open. 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 Town Car and Continental, 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, closing the relay contacts and sending voltage to the A/C clutch.

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