Engine Controls - Theory & Operation - Diesel: Other Ford Excursion I

MANIFOLD INTAKE AIR HEATER STARTING AID SYSTEM

The Manifold Intake Air Heater (MIAH) system consists of the following components: intake air heating element, intake air heater relay, Engine Oil Temperature (EOT) sensor, Intake Air Temperature (IAT) sensor, Powertrain Control Module (PCM) and starter switch. MIAH improves starting and helps reduce White smoke and odor during cold weather conditions and on extended idles.

The PCM will activate the system when ambient air temperature is below 32°F (0°C), oil temperature is less than 131°F (55°C) and battery voltage is more than 11.7 volts. MIAH will stay on for 30 minutes as long as engine idles and previous conditions are met. MIAH will only activate once per "key on event". If MIAH is activated, then vehicle is driven, MIAH will not activate again when engine is brought back to idle.

Econoline

Turbocharger is a non-wastegate controlled turbocharger. The turbocharger consists of a gas turbine and air compressor wheel mounted on opposite ends of a common shaft. The wheels are enclosed by housings. The shaft is enclosed by a center housing. Internal components of turbocharger are oil and air cooled. Engine oil is circulated through the center housing that acts as a heat barrier between the hot turbine and cold compressor. The shaft bearings are a sleeve type and are lubricated by engine oil.

High velocity engine exhaust gases drive the turbine shaft assembly at speeds up to 130,000 RPM. Filtered air entering the compressor side of the turbocharger is compressed and delivered to the cylinder heads at a pressure higher than atmosphere. More air being delivered to intake manifold portion of cylinder head results in more power, fuel efficiency and a better ability to maintain power at altitude.

Turbocharger is supplied with pressurized oil from the engine's main oil gallery through a passage in the turbocharger pedestal. Oil then drains back through another passage in the turbocharger pedestal into the oil pan. This eliminates the need for external lubrication supply and return lines.

Split ring seals are installed at each end of the common shaft between the shaft bearing and wheel assembly to prevent lubricating oil from entering the turbine or compressor area. The pressurized oil entering the turbocharger is also used to actuate the exhaust backpressure warm-up system. This system consists of an actuator and a butterfly valve. Warm-up system only operates during cold weather warm-up cycle.

Excursion & Pickup

The Garret TP-38 turbocharger is an electronically controlled wastegate turbocharger. An analog Manifold Absolute Pressure (MAP) sensor provides manifold pressure readings to Powertrain Control Module (PCM). PCM compares MAP readings, vehicle speed signals and calculated load value and sends a signal to solenoid control valve which operates the wastegate actuator. Wastegate actuator provides proper positioning for wastegate valve which provides proper boost pressure.

The turbocharger consists of a gas turbine and air compressor wheel mounted on opposite ends of a common shaft. The wheels are enclosed by housings. The shaft is enclosed by a center housing. Internal components of turbocharger are oil and air cooled. Engine oil is circulated through the center housing that acts as a heat barrier between the hot turbine and cold compressor. The shaft bearings are a sleeve type and are lubricated by engine oil.

High velocity engine exhaust gases drive the turbine shaft assembly at speeds up to 130,000 RPM. Filtered air entering the compressor side of the turbocharger is compressed and delivered to the cylinder heads at a pressure higher than atmosphere. More air being delivered to intake manifold portion of cylinder head results in more power, fuel efficiency and a better ability to maintain power at altitude.

Turbocharger is supplied with pressurized oil from the engine's main oil gallery through a passage in the turbocharger pedestal. Oil then drains back through another passage in the turbocharger pedestal into the oil pan. This eliminates the need for external lubrication supply and return lines.

Split ring seals are installed at each end of the common shaft between the shaft bearing and wheel assembly to prevent lubricating oil from entering the turbine or compressor area. The pressurized oil entering the turbocharger is also used to actuate the exhaust backpressure warm-up system. This system consists of an actuator and a butterfly valve. Warm-up system only operates during cold weather warm-up cycle.

COMPUTERIZED ENGINE CONTROLS

The EEC-V system provides control of engine and automatic transmission through the PCM. EEC-V system has an On-Board Diagnostics (OBD-II) monitoring system. For additional information, see SELF-DIAGNOSTICS - EEC-V - DIESEL article.

POWERTRAIN CONTROL MODULE

During system operation, PCM transmits electrical reference signals to engine sensors and analyzes return signals to determine engine and A/T operating conditions. If PCM perceives that a sensor, circuit or actuator has failed, it will initiate Failure Mode Effects Management (FMEM) strategy, allowing vehicle to continue to be driven. PCM is located in left rear of engine compartment, near brake master cylinder. The PCM controls malfunction indicator light and communicates with scan tool via data link connector, allowing for PCM to be reprogrammed by flash electrically erasable programmable read only memory.

INJECTOR DRIVER MODULE

The IDM interfaces with PCM to energize fuel injectors. IDM receives 2 digital control signals from PCM: camshaft position signal (for cylinder identification) and Fuel Delivery Command Signal (FDCS). FDCS is used by IDM to control injection timing and duration. CMP signal provides synchronization to engine's first and fifth injector (firing order, cylinders No. 1 and 4). IDM also verifies that FDCS and CMP occur at valid timing intervals for synchronization. IDM is located in left side of engine compartment and has a 40-pin connector.

Note. Components are grouped into 2 categories. The first category is INPUT DEVICES , covering components which control or produce voltage signals monitored by PCM. The second category is OUTPUT DEVICES , covering components controlled by PCM.

ENGINE TIMING

The PCM controls both duration and timing of injection event with Fuel Delivery Control Signal (FDCS). Signal duration, or fuel pulse width, is shown as FUEL_PW PID on scan tool. PCM controls fuel plunger injection pressure and fuel volume by varying injection oil pressure with Injection Pressure Regulator (IPR). The command to IPR is a 12-volt, Pulse Width Modulated (PWM) signal (controlled on ground side). Injection oil pressure command is shown as NGS PID IPR which is the percentage ON of pulse width modulated signal. Injection oil pressure is shown as NGS PID ICP. PCM receives engine rotational position information from Camshaft Position (CMP) sensor. CMP is a Hall effect device. It outputs 12 volts to PCM whenever it detects iron of a spoked target wheel in front of it, and it outputs zero volt whenever it detects space between spokes. The target wheel spokes and spaces are each 15 crank degrees, except for narrow spoke which indicates cylinder No. 1 and a wide spoke which indicates cylinder No. 4 (fires 5th). Scan tool RPM PID is generated by PCM from CMP signal.

INPUT DEVICES

Vehicles are equipped with different combinations of input devices. Not all devices are used on all models. To determine the input device usage on a specific model, see appropriate wiring diagram in WIRING DIAGRAMS article. The following input signals are available.

Accelerator Position Sensor (Econoline)

The Accelerator Position (AP) sensor is a 3-wire potentiometer that receives VREF from PCM, and returns a signal to PCM proportional to accelerator pedal position. AP sensor signal is used in calculating fuel quantity. AP sensor input is used by PCM to control exhaust backpressure regulator. AP sensor is mounted above accelerator pedal. (Scheme 83) The AP sensor is not serviced separately. If sensor is defective, accelerator pedal assembly must be replaced. If PCM detects a fault with AP sensor signal, PCM will cause MIL to illuminate. An AP signal that is detected out of range (high or low), will cause PCM to only allow engine to operate at low idle only.

Scheme 83

A/C Pressure Switch

Note. The ACPSW may also be referred to as refrigerant containment switch.

The A/C Pressure Switch (ACPSW) is located in the high pressure (discharge) side of A/C system. Normally closed contacts in ACPSW open when A/C head pressure reaches maximum level, which turns off A/C by opening the A/C demand circuit and prevents A/C high pressure relief valve from opening. PCM modifies automatic transmission shift scheduling when A/C is on and KOER On-Demand Self-Test and Cylinder Contribution Test (CCT) are aborted. On Excursion, vehicle may be equipped with optional Electronic Automatic Temperature Control (EATC) system.

Analog Manifold Absolute Pressure Sensor

The Manifold Absolute Pressure (MAP) sensor is a variable capacitor sensor. MAP sensor provides a voltage signal to PCM that is proportional to intake manifold pressure to enable PCM to determine engine load and calculate fuel quantity. MAP sensor signal is also used to reduce smoke from exhaust by limiting fuel quantity during acceleration until a specified boost pressure is obtained. MAP sensor signal is used to indicate turbocharger boost pressure. MAP sensor is mounted to cowl in engine compartment.

Barometric Pressure Sensor

The Barometric Pressure (BARO) sensor is a variable capacitor that processes a signal indicating atmospheric pressure. Variations in atmospheric pressure (changes in altitude) modify an electrical signal which is monitored by PCM to calculate injection timing and glow plug control. If PCM detects a fault with BARO sensor, it will assume a default value of 14.5 psi (100 kPa). BARO sensor is located inside of PCM and cannot be replaced separately. PCM must be replaced to replace BARO sensor.

Brake Pressure Applied Switch

Note. BPA switch may also be referred to as deactivator switch or redundant speed control deactivator switch.

The Brake Pressure Applied (BPA) switch is a normally closed hydraulically controlled pressure switch that is located on the brake master cylinder. BPA switch senses brake fluid pressure and provides a back up to the brakelight switch signal to deactivate cruise (speed) control. The BPA switch is independent (mechanically and electrically) from the brakelight switch. BPA switch actuates after the brakelight switch is actuated.

All vehicles with hydraulic brakes have a single BPA switch. Normally, a brakes-applied signal from BPP switch will disengage speed control. If BPP switch signal is lost, BPA switch will supply brakes-applied signal to speed control servo.

Brakelight Switch

Note. Brakelight switch may also be referred to as Brake Pedal Position (BPP) switch.

The Brakelight switch is wired to brakelight circuit and PCM. Brakelight switch is located above brake pedal and signals PCM when brake pedal is applied. Brakelight switch input signal is used primarily for Torque Converter Clutch (TCC) lock/unlock strategy, cruise (speed) control and auxiliary idle control (if equipped). If all brakelights burn out, a pull-up resistor in PCM provides high voltage at PCM for fail-safe operation.

Camshaft Position Sensor

The Camshaft Position Sensor (CMP) sensor is a Hall Effect sensor that generates a digital frequency signal. PCM uses this signal to determine engine speed and position of camshaft. A target wheel (camshaft drive gear) has a narrow spoke which indicates cylinder No. 1 and a wide spoke which indicates cylinder No. 4 (5th in firing order). The RPM PID is generated by PCM from CMP signal. CMP sensor is located right front of engine, above crankshaft pulley.

Clutch Pedal Position Switch

The Clutch Pedal Position (CPP) switch detects when clutch pedal is depressed. CPP sends battery voltage to PCM when clutch pedal is released and zero voltage when clutch pedal is applied. PCM uses CPP switch signal to disable speed control system and Power Take-Off (PTO) raised idle mode. CPP switch is located at top of clutch pedal.

Digital Transmission Range Sensor

The digital Transmission Range (TR) sensor is located on side of transmission at manual lever. The digital TR sensor opens or closes a set of 4 switches that are monitored by PCM. The internal switch signal corresponds with position of gear shift lever. Digital TR sensor sends neutral/start signal to PCM. Malfunction of digital TR sensor may cause harsh engagements and firm shift feel. Improper shifting or shift selection and no engine cranking may also result.

Electronic Air Filter Minder Indicator

Although the electronic air filter minder sensor is an instrument cluster input and not a PCM input, it can create an engine performance concern if faulty. On Excursion and F250-550, an electronic air filter minder sensor is located in air inlet box and is wired to instrument cluster from the sensor. When restriction in air inlet system reaches an amount that indicates restriction, the sensor's internal switch will close and air filter minder indicator will illuminate.

Electronic Throttle Control (Except Econoline)

The Electronic Throttle Control (ETC) combines the Accelerator Pedal (AP) sensor and Idle Validation Switch (IVS) into a single unit. AP sensor function provides PCM with driver's demand for power. ETC sensor portion is a 3-wire potentiometer that receives VREF from PCM and returns a signal to PCM proportional to accelerator pedal position. ETC signal is used in calculating fuel quantity. Also, ETC input is used by PCM to control Exhaust Back-Pressure (EBP) regulator. EBP system is not used on F650-750. Idle validation function verifies when accelerator pedal is in idle position. This switch protects against in-range failure of ETC sensor. A PCM detected fault of ETC sensor will illuminate MIL in instrument cluster. An ETC signal that is detected out of range (high or low) will cause PCM to only allow engine to operate at low idle.

Engine Coolant Temperature Sensor

The Engine Coolant Temperature (ECT) sensor is a thermistor which sends coolant temperature signal to PCM. ECT sensor resistance changes in response to coolant temperature. ECT sensor resistance decreases as temperature increases. ECT sensor is located on top of water pump assembly.

Engine Oil Temperature Sensor

The Engine Oil Temperature (EOT) sensor is a thermistor mounted to oil reservoir whose resistance decreases as engine oil temperature increases. PCM uses EOT signal to calculate fuel quantity, injection timing, glow plug operation and exhaust backpressure. When ambient temperatures are less than 122°F (50°C), low idle speed is increased to a maximum of 1300 RPM to warm up engine. If PCM detects an EOT sensor fault, it will assume an engine oil temperature of 68°F (20°C) for starting purposes and 212°F (100°C) for operating purposes. MIL will illuminate as long as fault exists. EOT is located on top left side of engine. (Scheme 84)

Scheme 84

Exhaust Backpressure Sensor

The Exhaust Backpressure (EBP) sensor is a variable capacitor that is supplied VREF by PCM and returns a linear analog voltage signal that indicates exhaust backpressure in right side exhaust manifold. PCM uses this signal along with the EBP regulator to form a closed loop exhaust backpressure control system. When ambient air temperature is less than 45°F (7°C) and engine oil temperature is less than 167°F (75°C), EBP valve restricts exhaust flow, providing more heat to engine coolant for cab heating during low load and low speed operating conditions. If PCM detects an EBP fault, it will disable exhaust backpressure control. EBP sensor is located on top front of engine. (Scheme 84)

Idle Validation Switch

The PCM uses Idle Validation Switch (IVS) signal to verify when accelerator pedal and shaft is in idle position. Any detected malfunction of IVS will illuminate MIL and engine will operate at low idle only. IVS is not serviced separately. IVS is part of accelerator pedal assembly. (Scheme 83) If IVS is defective, accelerator pedal assembly must be replaced.

Injection Control Pressure Sensor

The Injection Control Pressure (ICP) sensor is a variable capacitor that is sent VREF by PCM and returns a linear analog voltage signal that indicates measured oil pressure in left side injection rail. PCM uses this signal to command correct injector timing, pulse width and injection control pressure for proper fuel delivery at all speed and load conditions. ICP sensor is used along with ICP regulator to form a closed loop fuel pressure control system. If PCM detects an inoperative ICP sensor, PCM will control injection control pressure from a PCM-estimated injection control pressure. ICP sensor is located on top of engine near rear of generator.

Injector Driver Module Feedback

The Injector Driver Module (IDM) provides an EF signal to PCM which confirms that proper timing and duration of PCM command was received by IDM. The EF signal is also used to send diagnostic information about IDM and fuel injector circuitry to PCM.

Intake Air Temperature Sensor

The Intake Air Temperature (IAT) sensor is a thermistor which sends intake air temperature signal to PCM. The IAT sensor resistance changes in response to air temperature. As air temperature increases, IAT sensor resistance decreases and as air temperature decreases, IAT sensor resistance increases. IAT sensor is located under air filter housing. PCM uses IAT sensor information to operate Exhaust Backpressure (EBP) system and determines cold idle set point. During long idle periods in cold weather, set point will increase engine RPM.

Manifold Air Temperature Sensor (Except Econoline)

The MAT sensor is a thermistor which sends intake air temperature signal to PCM. The MAT sensor resistance changes in response to air temperature and PCM adjusts fuel and timing accordingly. The MAT sensor resistance decreases as air temperature increases. MAT sensor is located in compressor manifold downstream from intercooler.

Parking Brake Signal Switch

Note. Parking brake switch may also be referred to as park brake switch or Parking Brake Applied (PBA) switch.

The parking brake signal switch is located on top of parking brake pedal. When parking brake is applied, parking brake signal switch sends a signal to PCM to disable cruise (speed) control operation. On Econoline, Excursion and F250-550, parking brake signal switch is located under instrument panel. On F650-750 with hydraulic brakes, parking brake switch is mounted under hand brake boot. On F650-750 with air brakes, switch is located in engine compartment, near center of vehicle.

Speed Control Command Switches

Speed control command switches are momentary switches which send one of several resistance values to PCM to select speed control functions. Switches are located on steering wheel.

Transmission Control Switch

The Transmission Control Switch (TCS) is located on end of automatic transmission gearshift lever. When TCS is pressed, Transmission Control Indicator Light (TCIL) illuminates and key power is sent to PCM. Overdrive gear is then disabled by PCM.

Vehicle Speed Sensor

On Econoline, Vehicle Speed Sensor (VSS) is mounted in extension housing of transmission. VSS is a variable reluctance or Hall Effect type sensor that generates a waveform with a frequency proportional to vehicle speed. PCM uses the frequency signal generated by VSS (and other inputs) to control fuel injection, transmission shift and Torque Converter Clutch (TCC) scheduling. On Excursion and F250-550, VSS is mounted in rear differential housing. The speed sensor ring is located inside of differential housing between ring gear and differential carrier assembly. VSS signal is sent from Generic Electronic Module (GEM) to PCM with a vehicle speed signal.

4x4 Low Switch

The 4x4 low switch is located on transfer case cover. The 4x4 low switch sends a ground signal to instrument cluster when in 4x4L. Using Standard Corporate Protocol (SCP), instrument cluster provides a 4x4 status signal to PCM. PCM modifies shift schedule with output signals to transmission Electronic Pressure Control (EPC) solenoid.

OUTPUT DEVICES

Note. For theory and operation on components, refer to indicated system.

Exhaust Backpressure Regulator

Note. The Exhaust Backpressure (EBP) regulator may also be referred to as exhaust backpressure solenoid.

The EBP regulator and EBP piston are contained in turbocharger mounting pedestal. EBP valve is a variable position valve that controls exhaust backpressure during cold ambient temperatures to reduce warm-up period. Turbocharger pressurized lube oil is routed to EBP solenoid, which regulates oil pressure and actuates EBP piston. EBP piston operates EBP valve in exhaust housing. Powertrain control module uses the measured exhaust backpressure, intake air temperature and engine load to determine the desired exhaust backpressure. If EBP regulator is defective, turbocharger must removed to access EBP regulator.

Glow Plug Control (California Emissions)

Note. On Glow Plug Control Module (GPCM) equipped vehicles, WAIT TO START light "on" time is independent from GPCM "on" time.

The glow plug system is composed of solid state GPCM, glow plugs and associated wiring. Glow plug "on" time is controlled by PCM and is a function of engine oil temperature, barometric pressure and battery voltage. Glow plug "on" time varies between 1-120 seconds. In addition to PCM control, GPCM internally limits glow plug operation to 180 seconds regardless of PCM commanded "on" time. Power to glow plugs is provided though GPCM solid state drivers directly from battery. Failures detected by GPCM are passed to PCM using a serial communication signal. GPCM is located on top of engine. (Scheme 84)

Glow Plug Control (Federal Emissions)

Glow plugs are used to improve cold engine starting and to eliminate White smoke. PCM uses Engine Oil Temperature (EOT) sensor and Barometric Pressure (BARO) sensor to determine how long glow plugs will be on. (Scheme 85) PCM energizes glow plugs longer if engine is very cold or if barometric pressure is low at high altitudes. An open in glow plug relay circuit will not allow glow plugs to operate. A glow plugs "always on" condition can be caused by a short circuit. Glow plug relay is located on top of engine. (Scheme 84)

Scheme 85

Glow Plug Indicator

The Glow Plug Light (GPL) is located in instrument cluster and is used to prompt operator when engine is ready to be cranked and started. When light goes out, vehicle is ready to start. As a bulb check, GPL is commanded on at every key cycle even though glow plug system may not be required. "On" time normally varies between 1-10 seconds. WAIT TO START indication is independent of glow plug relay "on" time as glow plug system can stay on after indicator goes off. On Excursion and F250-550, GPL indicator is controlled by instrument cluster, based on electronic information from PCM. PCM sends an electronic signal command, through Standard Corporate Protocol (SCP) communications to cluster on how long to keep indicator on. Instrument cluster performs diagnostics for GPL circuit. On Econoline, indicator lamp is turned on by PCM and performs diagnostics for GPL circuit.

Injection Pressure Regulator

See FUEL CONTROL under FUEL SYSTEMS.

Malfunction Indicator Light

See MALFUNCTION INDICATOR LIGHT under SELF-DIAGNOSTIC SYSTEM.

Manifold Intake Air Heater

See MANIFOLD INTAKE AIR HEATER under EMISSION SYSTEMS.

Speed Control Indicator

Econoline and F250-550 models have a speed control (cruise control) indicator light in instrument cluster that will illuminate when speed control is engaged. PCM illuminates indicator by providing a ground path.

Tachometer

The tachometer is controlled by instrument cluster. The instrument cluster receives electronic information from PCM for engine speed (RPM), through Standard Corporate Protocol (SCP) communications. The electronic signal is a buffered representation of Camshaft Position Sensor (CMP) signal. An open or short circuit of tachometer output wiring will result in an inoperative tachometer.

Transmission Solenoids

See TRANSMISSION SOLENOIDS under MISCELLANEOUS CONTROLS.

Water in Fuel Indicator

Excursion and F250-550 models are equipped with a WATER IN FUEL indicator which is controlled by instrument cluster. The instrument cluster receives electronic information from PCM for water in fuel status, through Standard Corporate Protocol (SCP) communications. If water in fuel sensor senses water in the fuel separator/housing, PCM sends an SCP message to instrument cluster to illuminate WATER IN FUEL indicator.

Fuel Pump

Fuel is supplied by an electric fuel pump. Fuel pump is located on driver's side frame rail. Fuel is drawn from fuel tank through the primary filter (screen on fuel tank sending unit) by electric fuel pump. (Scheme 86) Pressurized fuel, about 45-80 psi (310-552 kPa) is supplied to secondary filter located in fuel filter housing on top of engine by means of electric fuel pump and pressure regulator valve. Pressure regulator relieves fuel pressure by sending fuel back to fuel tank. Only filtered fuel going through fuel filter will go to cylinder heads. A fuel check valve is located on each cylinder head to prevent fuel pressure spikes in fuel rail.

Scheme 86

Fuel Filter

Fuel filter uses a replaceable element design. Filter is located in fuel filter/water separator housing on top of engine.

Fuel/Filter Water Separator

Fuel/filter water separator is located on top of engine. Water should be drained from separator whenever WATER IN FUEL indicator light is illuminated or every 5000 miles. WATER IN FUEL indicator light will illuminate when about one quart of water has accumulated.

Injection Control

The pressure control system uses hydraulically-actuated injectors to pressurize the fuel inside of injectors. Engine oil is used to actuate injectors. Oil is drawn from oil pan through the pick-up tube by engine oil pump. Engine oil pump is a rotor-type pump driven by crankshaft. Oil is fed through passages in front cover to an oil reservoir mounted on top on front cover. The oil reservoir makes a constant supply of oil available to the high pressure oil pump mounted on top of engine. (Scheme 87) Injection Pressure Regulator (IPR) controls oil pump injection oil pressure between 450-3000 psi (3102-20,685 kPa). See INJECTION PRESSURE REGULATOR.

High pressure oil is sent to oil galleries machined in cylinder heads. An Injection Control Pressure (ICP) sensor is mounted on one of the oil galleries and sends an analog voltage signal to PCM for feedback control of oil pressure. When an injector is electrically energized, a poppet valve is opened by an electronic solenoid mounted on injector. (Scheme 88) Oil pressure is then allowed to flow into injector and act on the amplifier piston. When injection is ended, pressure on top of amplifier piston is vented by the poppet valve through the top portion of injector. Oil is then directed by oil troughs mounted on injector to a push tube hole to return to crankcase.

Scheme 87

Scheme 88

Injection Pressure Regulator (IPR) controls injection oil pressure. An electrical signal sent to a solenoid creates a magnetic field which applies a variable force on a valve servo to control pressure. Fuel quantity delivered to combustion chamber is proportional to injection control pressure. An open circuit will result in minimum oil pressure and a no-start situation. A short circuit results in maximum oil pressure. A mechanical pop-off valve limits oil pressure to 4000 psi (27,580 kPa). IPR is located on top of engine. (Scheme 84)

Fueling Corrections

The PCM adjusts injector output based on oil temperature information received from Engine Oil Temperature (EOT) sensor. Turbo boost information is received from Manifold Absolute Pressure (MAP) sensor and Barometric (BARO) pressure sensor. These corrections are necessary to meet emissions requirements and to optimize power. Engine Coolant Temperature (ECT) sensor is used as primary input to electronic control system to enable adaptive cooling. This provides a means of providing adequate cooling in severe engine temperature conditions. When ECT is greater than 225°F (107°C), fueling rate of engine is modified to provide cooling protection and prevent engine damage due to overheating. Outputs of these sensors are displayed on scan tool as EOT (temperature), MAP (boost pressure), BARO (pressure), and BARO V (volts). MGP shows boost.

The Manifold Intake Air Heater (MIAH) is designed to reduce White smoke from exhaust during long idling periods and during start-up in cold ambient temperatures. MIAH system consists of the MIAH, Powertrain Control Module (PCM), PCM power relay and MIAH relay assembly. The following conditions must be met prior to PCM activating MIAH

1. Ambient temperature must be less than 32°F (0°C).
2. Engine oil temperature must be less than 131°F (55°C).
3. Vehicle power (VPWR) must be 11.8-15.0 volts.
4. Parking brake must be applied on M/T models.
5. Gearshift lever must be in Park or Neutral on A/T models.
6. Glow plugs must be off.

The Malfunction Indicator Light (MIL) will illuminate when ignition switch is turned to ON position (bulb check), or when systems related to EEC-V diesel system malfunction during normal engine operation. For additional information, see SELF-DIAGNOSTICS - EEC-V - DIESEL article.

Transmission solenoids are used to shift transmission gear ratios, apply Torque Converter Clutch (TCC) and provide coasting on deceleration. Ground signal is controlled by PCM. Power is supplied to solenoids from power relay. For additional information, see FORD 4R100 DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.