A coil in a coil pack (Figure 47) 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) (Figure 48) 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 Camshaft Position (CMP) Failure Mode Effects Management (FMEM) .
Engine Crank/Engine Running
During engine crank the Powertrain Control Module (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.
During CMP Failure Mode Effects Management (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
The PCM monitors certain parameters (such as engine coolant temperature, vehicle speed, A/C on/off status, Air Conditioning (A/C) pressure, etc) to determine engine cooling fan needs. 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.
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, Continental, Town Car and Lincoln LS6/LS8 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 Standard Corporate Protocol (SCP) .
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 Engine Control (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 Fuel Pump Power (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 (Figure 49) 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 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
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.
Hydraulic Cooling Fan Drive
The system consists of an engine-driven pump with an integral solenoid (Figure 50) on the pump that is triggered by the powertrain control module (PCM). Fan speed is controlled by adjusting current to the solenoid, which then changes the fluid flow to the hydraulic motor. More current means the solenoid opens up, allowing higher pressure to increase the fan speed. The fan always turns due to solenoid current leakage, even in cold engine cases. The motor is driven by the pump. It contains a shaft on which the fan mounts. The motor also contains quick connect fittings for the high pressure lines. The cooler is similar to the power steering cooler (same purpose and function, to keep the fluid cool).
Thermostat 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 51)that has a resistive heater within the wax element. The heater is controlled by the PCM dependent on engine speed, throttle position, engine load, vehicle speed, 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 115°C (239°F) . Energizing the heater will reduce the opening temperature to about 80°C (176°F) and the fully open temperature to 110°C (230°F) .
Wide Open Throttle A/C Cut-Off
The wide open throttle A/C cutoff relay (may be referred to as the A/C clutch 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 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), A/C Cycling Switch (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 Wide Open Throttle A/C (WAC) output, closing the relay contacts and sending voltage to the A/C clutch.
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 2.22Hz 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.