Engine Controls - Pinpoint Tests - 6.0L Diesel: Other Ford Econoline E250

Connector Checks to Ground (B-)

Measure the resistance of all wiring harness connectors to ground (preferably the negative battery cable) to determine if a short to ground condition is present. It is important that during this test all accessories, including the dome light, be turned off. Current flow in the system will affect resistance readings. If the reading is fluctuating greatly, disconnect the battery and measure to the negative battery cable.

1. Signal return should measure less than 5 ohms.
2. The VREF and signal lines, with the processor connected, will normally measure greater than 50 k ohms.
3. Power ground on an actuator circuit should measure less than 5 ohms. The control side of an actuator circuit will also normally measure greater than 50 k ohms.

Connector Voltage Checks

The next step is to turn the ignition key to the ON position and measure if the expected voltages are present at the connector. On circuits with expected voltages this test will verify the integrity of that circuit. On circuits without an expected voltage this test will determine if that circuit is shorted or miswired to a voltage source.

1. Signal return should measure less than 2.5 volts.
2. VREF should measure 4.5-5.5 volts. If this is higher or lower than expected, disconnect sensors one at a time to determine if a sensor is biasing the circuit and refer to «PINPOINT TEST B: REFERENCE VOLTAGE»(ref-225542-S22793258852006031800000) pinpoint procedures.
3. Signal lines will measure either 0-.25 V if the circuit is designed to pull down when disconnected or a higher voltage (normally 4.6-5, or 12 V) if it is designed as a pull up circuit. A pull up signal circuit that measures the expected value normally indicates a good circuit.
4. Actuator circuits may be either on/off type circuits (normally 12 volts) or pulse width modulated circuits (12 volts controlled by a % duty cycle).
5. Communication circuits are similar to sensor circuits when disconnected in that they will be designed to either pull up or pull down when disconnected. Measuring the expected voltage of a communication circuit when disconnected will often discern its condition.

Circuit Function

With the ignition switch in the START or RUN position, voltage is applied to the coil of the powertrain control module (PCM) relay. The applied voltage energizes the relay and closes the internal relay contacts. With the relay contacts closed, vehicle power (VPWR) is supplied to the PCM.

Fault Detection

Vehicle power is monitored by the PCM. When the voltage is above or below a pre-calibrated value, an internal counter will increment until a DTC is set.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

Scheme 87

Scheme 88

1. P0560 = System Voltage
2. P0562 = System Voltage
3. P0563 = System Voltage High

Reference voltage (VREF) is a positive voltage (approximately 5.0 volts +/- 3%) that is an output by the powertrain control module (PCM). This consistent voltage is used by all 3-wire sensors. Signal return (SIG RTN) is a dedicated ground used by most sensors and some other inputs.

Note. Enter this pinpoint test only when a check for VREF has failed in the sensor pinpoint tests for 3-wire sensors and actuators.

Note. A VREF circuit shorted to ground will cause a no-start condition. No DTCs will be present due to the inability of the PCM to communicate with the scan tool.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

Remember

This pinpoint test is intended to diagnose only the following

Scheme 89

1. sensor harness circuits: SIG RTN, VREF
2. 3-wire sensors and actuators
3. PCM

Signal Functions

The normally closed clutch pedal position (CPP) switch detects when the clutch pedal is pressed (manual transmissions) to disable the speed control system and PTO and raised-idle mode. Switch actuation occurs as the clutch is initially pressed prior to disengaging the transmission at the top of travel.

Scheme 90

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

The crankshaft position (CKP) signal source is a variable reluctance sensor mounted in the right front side of the engine block. The sensor reacts to a target wheel on the crankshaft. The target wheel is a 60 minus 2 tooth steel disk with 58 evenly spaced teeth and a SYNC gap (a minus 2 slot wide tooth). The sensor produces pulses for each tooth edge that passes it. Crankshaft speed is derived from the frequency of the CKP sensor signal. The crankshaft position is determined by synchronizing the SYNC tooth with the SYNC gap signals from the target wheel. Diagnostic information on the CKP input signal is obtained by carrying out accuracy checks on frequency, and duty cycle with software strategies.

The powertrain control module (PCM) uses the CKP and camshaft position (CMP) signal to calculate engine speed and piston position. The CKP creates a signal used by the PCM to indicate cylinder identification in a particular bank. The CKP contains a permanent magnet that creates a magnetic field. The signal is created when the target wheel rotates and breaks the magnetic field created by the sensor. The engine will not operate without a CKP signal.

Engine Speed - Is determined by counting the 15 windows on the crankshaft gear each crankshaft revolution.

Injection Control Pressure - Engine speed is one of the controlling variables in the calculation of desired injection control pressure.

Exhaust Pressure - Exhaust pressure control is a function of engine speed and load.

Fuel Quantity Control/Torque Limiting - Engine torque and fuel is controlled and is dependent on engine speed. Fuel quantity is determined by engine speed.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

Note

This pinpoint test is intended to diagnose the following

Scheme 91

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Scheme 93

1. CKP sensor
2. harness circuits: CKP (+), CKP (-), CKP out and CKP shield
3. PCM

The manifold absolute pressure (MAP) sensor is a variable capacitance sensor that, when supplied with a 5-volt reference signal from the powertrain control module (PCM), produces an analog voltage signal that indicates pressure.

Smoke Control - The MAP signal is used to control smoke by limiting fuel quantity during acceleration until a specified boost pressure is obtained.

Dynamic Injection Timing - Optimizes injection timing for boost pressure measured.

Fault Detection/Management

A MAP signal that is detected by the PCM to be out of range or at an incorrect value for specific conditions will cause the PCM to ignore the MAP signal and operate the engine from an inferred boost pressure signal.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

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Scheme 95

The intake air temperature (IAT) sensor, located inside the mass air flow housing, is a thermistor-type sensor with a variable resistance that is inversely proportional to temperature changes. When interfaced with the powertrain control module (PCM), it produces a 0-5 volt analog signal that will measure temperature.

The IAT sensor's primary function is to measure intake air temperature to control timing and fuel rate when cold-starting. Continuous monitoring by the IAT sensor limits smoke emission.

An IAT signal that is detected out of range high or low by the PCM will cause the engine to ignore the IAT signal and assume an ambient temperature of 25 °C (77°F).

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

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Scheme 97

Circuit Functions

The intake air temperature 2 (IAT2) sensor is a thermistor-type sensor with a variable resistance that is inversely proportional to temperature changes. When interfaced with the powertrain control module (PCM), it produces a 0-5 volt analog signal that will measure temperature.

The primary function of the IAT2 sensor is to provide a feedback signal to the PCM indicating manifold air temperature.

The PCM continuously monitors the IAT2 sensor. If the PCM detects the signal voltage is higher or lower than expected, a DTC will be set.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

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Scheme 99

The barometric pressure (BARO) sensor is a cab-mounted variable capacitance sensor used to determine altitude. The BARO signal affects injection timing and fuel quantity to optimize engine operation and control smoke throughout all altitude conditions. The BARO signal is one of the variables used to calculate glow plug ON time. At higher altitudes, glow plug ON time is increased to reduce start-up smoke.

A BARO signal that is detected out of range high or low will cause the powertrain control module (PCM) to ignore the BARO signal and use the manifold absolute pressure (MAP) signal generated at low idle as an indication of barometric pressure.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

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Scheme 102

1. P0107 = BARO Sensor Low Input
2. P0108= BARO Sensor High Input NOTE: Compare BARO sensor value with local barometric values.

Early Build Applies To F-SuperDuty/Excursion - Early Build. Late Build Applies To E-Series Or F-SuperDuty/Excursion - Late Build.

Signal Function

The parking brake switch provides an input signal to the powertrain control module (PCM) indicating the current status of the parking brake (applied or released). The parking brake signal circuit is pulled to ground with the application of the parking brake.

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Scheme 104

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

The mass airflow (MAF) sensor measures the airflow rate into the engine and provides an analog signal to the powertrain control module (PCM) which is used to calculate air flow for the EGR monitor.

Current PCM implementation contains a mass airflow interface, which consists of a two pole, differential input, low pass filter. This filter is designed to pass an analog signal, originating from the mass air sensor, while rejecting unwanted ignition noise, high frequency electrical interference, and ground offsets.

The input to the interface is the analog voltage signal difference between MAF+ (mass airflow signal) and MAF- (mass airflow signal return). The MAF sensor outputs an analog voltage signal calibrated to 0.5 V at the lower limit of the flow range and 4.75 V at the upper limit of the flow range.

The intake air temperature (IAT) is also integrated into the MAF sensor. The PCM uses the IAT signal to control timing and fuel rate during cold starts.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

This pinpoint test is intended to diagnose the following

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Scheme 106

1. MAF sensor
2. harness circuits: MAF SIG, MAF RTN, vehicle power (VPWR), and power ground (PWR GND)
3. PCM

The engine coolant temperature (ECT) sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases, and increases as the temperature decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signals to the powertrain control module (PCM) corresponding to temperature.

The engine coolant sensor is used as the primary input to the electronic control system to enable adaptive cooling. This provides a means of providing adequate cooling in severe engine temperature conditions. The PCM will limit the fueling rate of the engine to provide cooling protection and prevent engine damage due to overheating.

The ECT sensor is located on the left side of the front cover. The PCM supplies a five volt reference signal that the ECT sensor uses to produce an analog voltage, indicating temperature. The PCM continuously monitors the signal of the ECT sensor to determine if the signal is within an expected range. If the PCM detects an out of range high or low, the PCM will ignore the ECT signal and substitute the EOT signal. If both ECT and EOT signals are out of range, the PCM will assume an engine coolant temperature of -34°C (-29°F) for starting and 82°C (180°F) for engine running conditions.

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Scheme 108

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

TEMPERATURE VS. RESISTANCE VALUES (APPROXIMATE)

The variable geometry turbocharger (VGT) is controlled by the powertrain control module (PCM). The PCM utilizes an exhaust pressure (EP) sensor to monitor the pressure and adjust the VGT solenoid duty cycle. The VGT solenoid receives a pulse width modulated (PWM) signal from the PCM that controls the solenoid on/off time. The VGT solenoid directs oil to a piston within the actuator housing. The direction of oil flow to the piston increases or decreases the exhaust pressure.

Sensor Bias

The VGT solenoid control is based on input sensors. The input sensors are used to calculate engine speed, desired fuel quantity, altitude, and exhaust pressure. The amount of voltage the sensor deviates from a calculated reference value (sensor bias) may cause a commanded versus actual pressure calculation error.

Detection/Management

The PCM monitors the exhaust pressure. A DTC is set when the difference between the commanded and the actual exhaust pressure is not within the calibrated limits.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

The engine oil temperature (EOT) sensor is a thermistor type sensor that has a variable resistance that changes when exposed to different temperatures. When interfaced with the powertrain control module (PCM), it produces a 0 to 5 volt analog signal that will deduce temperature.

Cranking Fuel Quantity/Timing Control - The EOT sensor signal is used to determine the timing and quantity of fuel required to optimize starting over all temperature conditions.

Idle Speed - At oil temperatures below 70°C (158 °F) low idle is incrementally increased to a maximum of 950 rpm.

Temperature Compensation - Fuel quantity and timing is controlled throughout the total operating range to ensure adequate torque and power is available.

Glow Plug Control - The Glow Plug Control Module (GPCM) and lamp ON times are controlled by engine oil temperature.

An EOT sensor signal that is detected out of range (high or low) by the PCM will cause the PCM to ignore the EOT sensor signal and assume an engine oil temperature of -20 °C (-4 °F) for starting and a temperature of 100 °C (212 °F) for engine-running conditions. The CHECK ENGINE light will also be illuminated as long as the condition exists.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

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Scheme 110

The fuel pump relay coil ground is controlled by the powertrain control module (PCM) with vehicle power (VPWR) supplied to the relay coil by the PCM power relay. Energizing the fuel pump relay closes the internal switch contacts and supplies B+ voltage through the inertia switch to the electric fuel pump. Fuel pump voltage is monitored by the PCM through the fuel pump monitor (FPM) circuit which is downstream of the inertia switch. When the ignition switch is turned on, the electric fuel pump will operate for approximately 20 seconds and will then be commanded off by the PCM if an RPM signal is not detected.

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The water in fuel (WIF) sensor is used to detect water in the fuel system and is located in the fuel control module. The WIF sensor is monitored by the powertrain control module (PCM). If the PCM detects water for more than 5 seconds, it will set continuous DTC P2269 and turn on the WATER IN FUEL indicator lamp (WIFIL). Route a hose from the fuel drain line to a 1 -qt clear container. Open the fuel control module drain valve. Close the valve when you have filled the container. Inspect fuel in the container. If no water or contaminants are in the container, you may have a circuit fault.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

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Scheme 118

Output Functions

Four High Side Driver Outputs (2 Right and 2 Left Bank) - The high side driver output function is to distribute energy to the correct bank based on a camshaft position output (CMPO) signal and provide regulated current to the injectors. The powertrain control module (PCM) commands the fuel quantity and the fuel injection control module (FICM) controls the duration of the injection event.

Low Side Driver Outputs - The low side driver outputs control the sequencing (firing order) of the engine.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

1. Key on.
2. Record the DTCs stored in KOEO On-Demand Self-Test and KOEO Injector Electrical Self-Test.
3. Access the Continuous DTCs.
4. Record the DTCs displayed.
5. CLEAR the DTCs.
6. DTCs are now cleared from memory. Repeat the KOEO On-Demand Self-Test and KOEO Injector Electrical Self-Test. Any DTCs that reappear are hard faults. If no DTCs reappear, then the fault is intermittent.

The fuel injection control module (FICM) is capable of detecting individual injector open and shorts to ground or voltage while the engine is running. The FICM is also capable of detecting right or left bank high side opens or shorts to ground. An on-demand injector self-test will allow the operator to verify operation of all injector solenoids with the engine off. FICM detected DTCs will not be transmitted if the inter-module (PCM to FICM) controller area network (CAN) is inoperative.

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Scheme 120

The injection control pressure (ICP) sensor is a variable capacitance sensor that, when supplied with a 5-volt reference signal from the powertrain control module (PCM), produces a linear analog voltage signal that indicates pressure.

The ICP sensor's primary function is to provide a feedback signal to indicate rail pressure so that the PCM can command the correct injector timing and pulse width and the correct injection control pressure for proper fuel delivery at all speed and load conditions.

Injection Control Pressure (ICP) Sensor Bias

The ICP sensor bias varies between sensors. The amount of voltage the sensor deviates from a calculated reference value (sensor bias) may cause an injection control pressure calculation error.

If the PCM detects an out of range high or low ICP sensor, the malfunction indicator (MIL) is illuminated and the PCM will function from an estimated injection control pressure (open loop control of injection control pressure).

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

Scheme 121

Scheme 122

The injection pressure regulator (IPR) is a pulse width modulated (PWM) variable position valve that regulates pressure in the injection control pressure (ICP) system. The IPR restricts the return flow path for oil from the high pressure pump. As the duty cycle increases, the IPR restriction to the drain increases, thus increasing the ICP. The IPR duty cycle is controlled by the powertrain control module (PCM) and is modulated from 0 to 65% dependent upon the desired injection control pressure.

An open or short to ground in the IPR control circuit can be detected by an on demand output circuit check performed during the KOEO test. An injection control pressure step test, in which the PCM commands and then measures specific preprogrammed pressures is performed during the KOER test.

The PCM is also capable of detecting whether desired injection control pressure is equal to measured injection control pressure while the engine is running. If the measured injection control pressure does not reasonably compare to the desired injection control pressure, the PCM ignores the measured ICP sensor signal and attempts to control the engine with the desired value. (If the problem was in the ICP sensor circuit this strategy causes minimal performance deterioration. If the problem is in the IPR control circuit, engine performance may be unsatisfactory).

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

Note. The engine will not operate with an IPR circuit that is not functioning.

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Scheme 124

The fuel injector control module (FICM) requires a 12-volt power source. The FICM receives power from the vehicle batteries through the FICM relay contacts each time the ignition key is turned on. As the ignition is turned ON, the FICM provides an internal ground to the coil side of the FICM relay. This closes the relay contacts and provides the FICM with necessary power.

Fault/Management

When the FICM continuously receives less than 7 volts or more than 16 volts, DTC P1378 or P1379 will set. DTC P1378 or P1379 may also cause DTCs P2552 and P0148 to set.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

Scheme 125

Scheme 126

The camshaft position (CMP) signal source is a magnetic pickup sensor mounted on the left front side of the engine block. The sensor reacts to a peg on a target wheel that is positioned on the camshaft. The peg will pass the sensor once per camshaft revolution and produce a single pulse correspondingly. Camshaft speed is calculated from the frequency of the CMP sensor signal. Diagnostic information on the CMP input signal is obtained by performing accuracy checks on signal levels, frequency and duty cycle with software strategies.

The powertrain control module (PCM) needs the crankshaft position (CKP) sensor and CMP signal to calculate engine speed and position. The CMP creates a signal that the engine control module (ECM) uses to indicate a particular bank. The CMP contains a permanent magnet that creates a magnetic field. The signal is created when the camshaft peg rotates past the sensor breaking the magnetic field. The engine will not operate without a CMP signal.

An inactive CMP signal during cranking is detectable by the PCM. An inactive CMP signal will cause a no-start condition. Electrical noise can also be detected by the PCM. If the level is sufficient to affect engine operation, a corresponding DTC will be set.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

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Scheme 129

The exhaust gas recirculation (EGR) actuator is a variable position valve that controls the amount of exhaust that enters the intake manifold. The EGR is controlled by the PCM using a pulse width modulated signal that varies from 0-100%. The EGR actuator consists of two components, a valve with actuator (solenoid) and a position sensor to monitor valve movement. The EGR sensor is a potentiometer sensor. When the EGR receives a 5-volt reference signal and a ground from the PCM, a linear analog voltage signal from the sensor will indicate position of the EGR valve.

The PCM will detect an open or short in the EGR control circuit after the KOEO test has run and set a DTC. The EGR actuator can be tested for a stuck or sticking valve by performing an output state low test while monitoring EGRP percentage.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

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Scheme 131

The exhaust pressure (EP) sensor is a variable capacitance sensor. A 5-volt reference signal from the powertrain control module (PCM) is utilized by the EP sensor to produce a linear analog voltage signal indicating exhaust pressure. The PCM uses the EP sensor input to control the variable geometry turbocharger (VGT) and the exhaust gas recirculation (EGR) systems.

The PCM will ignore an out-of-range high or low EP signal. If an out-of-range signal is detected, the EGR system will close and the PCM will default the VGT to calculated reference values.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

Scheme 132

Scheme 133

Scheme 134

1. P0470 = Exhaust Pressure Sensor
2. P0471 = Exhaust Pressure Sensor Range/Performance
3. P0472 = Exhaust Pressure Sensor Low Input
4. P0473 = Exhaust Pressure Sensor High Input

EP SENSOR SPECIFICATIONS - KPa/EP(Volts)

EP SENSOR SPECIFICATIONS - In-Hg/PSI

The 6.0L diesel speed control function is integrated into the powertrain control module (PCM). The momentary -contact steering wheel mounted switches are hardwired to the PCM. Pressing and releasing the ON switch turns the system on. Pressing and releasing the SET/ACCEL switch with the system on and a vehicle speed greater than 40 km/h (25 mph) activates the system. Tapping the SET/ACCEL or COAST switches increases or decreases the vehicle speed by 1.6 km/h (1 mph) per tap. If the respective switch is pressed and held, vehicle speed will accelerate or decelerate until the switch is released. Pressing and releasing the OFF switch or turning the ignition switch to the OFF position will deactivate the system. Standby mode is achieved with the application of the brake pedal. Pressing the RESUME switch with the system in standby mode will increase the vehicle speed until the last set speed is achieved.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

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Scheme 137

The powertrain control module (PCM) stores the vehicle operating conditions in random access memory (RAM) and utilizes this information to compensate for component variability. The keep-alive power (KAPWR) circuit supplies battery voltage (B+) to the PCM to maintain the memory contents when the ignition switch is off.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

Scheme 138

Enter this pinpoint test only when directed here.

This pinpoint test is intended to diagnose only the following

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Scheme 140

1. controller area network (CAN) communication circuits
2. harness circuits: chassis ground, power ground (PWR GND), battery voltage (VBAT), reference voltage (VREF)
3. powertrain control module (PCM) CAUTION: The PCM harness connectors must be properly seated and the connector latch properly attached to eliminate possible driveability concerns or a no start condition. Installing the PCM connectors on an angle may cause an improper connection, misdiagnosis and damaged components. Install the connector until the lever pivots and seats itself. Apply light pressure to get the connector into position on the PCM and then fully seat the connector. NOTE: Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension. NOTE: When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

The accelerator pedal position (APP) sensor provides the powertrain control module (PCM) with the driver's demand for power. The PCM determines the APP by processing input signals from the APP sensor.

The APP signal is used in calculating desired fuel quantity, injection timing and injection control pressure.

Any detected malfunction of the APP sensor will not illuminate the malfunction indicator lamp (MIL).

An APP signal that is detected out of range high or low by the PCM will cause the engine to ignore the APP signal and will only allow the engine to operate at low idle.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

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Note. Base idle should be no lower than 0.5 volt.

The visctronic drive fan (VDF) is an electrically actuated viscous clutch that consists of three main elements

1. a working chamber
2. a reservoir chamber
3. an actuator (electromechanical valve and speed sensor)

The actuator valve controls the fluid flow from the reservoir into the working chamber. Once viscous fluid is in the working chamber, "shearing" of the 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 fan speed. Fan speed is measured through a Hall-Effect sensor and is monitored by the PCM during closed loop operation.

The PCM optimizes fan speed based on engine coolant temperature (ECT), engine oil temperature (EOT), transmission fluid temperature (TFT), intake air temperature (IAT), or air conditioning requirements. When an increased demand for fan speed is requested for vehicle cooling, the PCM will monitor the fan speed through the Hall-Effect sensor. If a fan speed increase is required, the PCM will output the PWM signal to the fluid port, providing the required fan speed increase.

During KOER Self-Test, the PCM commands 100% duty cycle. A DTC is set if the PCM detects the voltage on the valve control circuit is not within the expected range or if the fan speed is less than a calibrated value.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

This Pinpoint Test is intended to diagnose the following

1. visctronic drive fan
2. fan speed sensor
3. harness circuits
4. powertrain control module (PCM)

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The brake pedal position (BPP) switch provides a 12-volt input signal to the powertrain control module (PCM) whenever the brake pedal is applied. The BPP switch input is used to deactivate the speed control system and the auxiliary powertrain control module (APCM).

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Scheme 148

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

The variable geometry turbo (VGT) actuator is a variable position valve that controls vane position in the turbine housing. The VGT is located on top of the turbocharger. The valve position is controlled by switching voltage source inside of the PCM.

The PCM continuously monitors the VGT circuit for an open or short.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

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Scheme 150

This pinpoint test is intended to diagnose only the following

1. harness circuits: KEY PWR, GND, BUS+, BUS
2. auxiliary powertrain control (APCM)

The injector control pressure is determined by the injection pressure regulator (IPR). The IPR is a variable position valve that controls injection control pressure. The powertrain control module (PCM) uses many input variables to determine the desired control pressure.

Battery voltage is supplied to the IPR when the ignition is in the ON position. Valve position is controlled by switching the output signal circuit to ground. The ON/OFF time is modulated from 0% to 65% dependent upon the desired control pressure.

The ICP sensor bias varies between sensors. The amount of voltage the sensor deviates from a calculated reference value (sensor bias) may cause an injection control pressure calculation error.

An open or shorted to ground control circuit can be detected by an on demand output circuit check performed during the KOEO test. When the starter is engaged and the engine fails to start, the IPR command will increase toward its maximum until the engine starts. The normal range for the IPR at idle is between 16-24%. An above 24% range indicates high effort to achieve idle. A below 16% indicates low effort to achieve idle.

The PCM is capable of detecting whether desired injection control pressure is equal to the measured injection control pressure while the engine is running. If the measured injection control pressure does not reasonably compare to the desired injection control pressure the PCM ignores the measured ICP sensor signal and attempts to control the engine with the desired value. (If the problem was in the sensor circuit, this strategy causes little performance deterioration. If the problem is in the control circuit, engine performance will probably still be unsatisfactory).

An injection control pressure step test, in which the PCM commands and then measures calibrated pressures, is performed during the KOER test.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

The engine will not operate with an IPR circuit that is not functioning.

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Scheme 152

The injection control pressure (ICP) sensor is a variable capacitance sensor that, when supplied with a 5-volt reference signal from the powertrain control module (PCM), produces a linear analog voltage signal that indicates pressure.

The ICP sensor's primary function is to provide a feedback signal to indicate rail pressure so that the PCM can command the correct injector timing and pulse width and the correct injection control pressure for proper fuel delivery at all speed and load conditions.

The ICP sensor bias varies between sensors. The amount of voltage the sensor deviates from a calculated reference value (sensor bias) may cause an injection control pressure calculation error.

If the PCM detects an out of range high or low ICP sensor, the malfunction indicator (MIL) is illuminated and the PCM will function from an estimated injection control pressure (open loop control of injection control pressure).

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

Scheme 153

Scheme 154

The injection control pressure (ICP) sensor is a variable capacitance sensor. A 5-volt reference voltage provided by the powertrain control module (PCM) is utilized by the sensor to produce a linear analog voltage proportional to hydraulic pressure.

The PCM monitors the ICP sensor signal to control the injection pressure regulator (IPR) duty cycle. The PCM will modulate the IPR based on the ICP signal to adjust the injector timing and injection pressure providing optimum fuel delivery at all speed, load, and temperature conditions.

If the PCM detects an out of range high or low ICP sensor, the malfunction indicator (MIL) is illuminated and the PCM will function from an estimated injection control pressure (open loop control of injection control pressure).

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

Scheme 155

Scheme 156

The misfire detection monitor is an on-board strategy designed to monitor engine misfire and identify the specific cylinder in which the misfire occurred. Misfire is detected using the crankshaft and camshaft position sensors. To determine if a misfire has occurred the powertrain control module (PCM) monitors deceleration of the crankshaft and compares the information received to engine speed and engine load. If a misfire event is determined, the PCM uses crankshaft position and the camshaft sensor signal information to determine which cylinder misfired.

The misfire detection monitor will be enabled only when certain engine conditions are satisfied. If the PCM is unable to detect which cylinder is misfiring or multiple cylinders are misfiring the PCM will set a random misfire DTC.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

The fuel injector control module (FICM) requires a 12-volt power source. The FICM receives power from the vehicle batteries through the FICM relay contacts each time the ignition is turned on. The powertrain control module (PCM) communicates with the FICM utilizing controller area network (CAN) protocol. The CAN protocol is an international standards organization (ISO) standard for serial data communication. The CAN standard includes a physical layer using differential transmission on a twisted pair of wires and a data link layer that defines a few different message types, arbitration rules for bus access and methods for fault detection and fault confinement.

The PCM monitors the communication circuits to the FICM for an open or short circuit.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

Scheme 157

Scheme 158

Scheme 159

The diesel engine power monitor (DEPM) strategy resides in the transmission control module (TCM) located inside the powertrain control module (PCM). The function of the DEPM is to monitor engine RPM when there is no power demand from the accelerator pedal position (APP) sensor.

Under normal engine idle operation, the DEPM RPM value must always be higher than engine RPM. In the event that the engine RPM does exceed the DEPM limit, the DEPM will disable the crank and cam output signal sent by the PCM to the fuel injection control module (FICM).

The fuel injection control module monitor (FICMM) input line informs the diesel engine power monitor (DEPM) when the injectors are turned on and when the injectors are turned off. When the FICMM line is either shorted or open, the monitor strategy assumes that the fuel injectors are always turned on and sets DTC P2552. When DTC P2552 is set, the DEPM may, in some instances, set DTC P0148. When DTC P0148 is set, DTCs P2614 (CMPO failure) and P2617 (CKPO failure) may also set. If DTCs P2614 or P2617 are set with P0148, do not attempt to diagnose the CMPO or CKPO circuits. DTCs P1378 or P1379 (FICM voltage) may also cause DTCs P2552, P0148, P2614 and/or P2617 to set.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

Scheme 160

Scheme 161

The powertrain control module (PCM) compares the BARO sensor and the MAP sensor reading at idle.

When the difference between the BARO sensor and MAP sensor is greater than a specified value, an increment counter advances until a DTC is set.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

The intake air temperature (IAT) sensor is a thermistor-type sensor with a variable resistance that changes when exposed to different temperatures. When interfaced with the powertrain control module (PCM), it produces a 0-5 volt analog signal that will measure temperature.

The 6.0L diesel utilizes two IAT sensors. The IAT sensor is integrated into the mass airflow (MAF) sensor.

The IAT2 sensor or manifold air temperature (MAT) sensor is located in the intake manifold. The IAT2 sensor provides a manifold air temperature signal to the PCM.

The PCM compares IAT2 to IAT at initial key on. When the difference between IAT2 and IAT is greater than the specified value for a given time, a DTC is set.

The exhaust gas recirculation (EGR) throttle position (EGRTP) actuator modifies the air flow into the intake manifold by controlling a throttle plate within the throttle body. A pulse width modulated (PWM) signal from the powertrain control module (PCM) is used to control the rotary motion of the EGRTP actuator. The throttle plate position is determined by an input signal from the EGR throttle position (EGRTP) sensor.

The EGRTP sensor is a rotary position sensor. A 5-volt reference voltage supplied by the PCM, is utilized by the sensor to provide an input signal that is proportional to the angle of the throttle plate.

Note. The PCM will activate the EGRTP actuator and perform a full sweep of the throttle plate for each key cycle with the IAT temperature greater than 0 °C (32 °F).

The PCM continuously monitors the intake throttle system. A DTC is set when a circuit fault is detected, there is a difference between commanded and actual EGRTP, the closed position is less than the minimum voltage of 3.85 volts at key on or the open position is greater than the minimum voltage of 0.93 volts at key on.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

Scheme 162

Scheme 163

Scheme 164

The BPA switch provides a backup signal for the brake pedal position (BPP) switch. If the BPP switch signal is lost, the BPA switch will provide the brakes-applied signal to deactivate the speed control system.

Note. Visually inspect the harness connectors for corrosion, damage, proper mating and correct pin tension.

Note. When the PCM is disconnected additional DTCs will be set. Clear all DTCs after restoring the vehicle.

Scheme 165

Scheme 166