Engine Controls - Pinpoint Tests - 6.0L Diesel: Other Ford Econoline E350 Super Duty

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 increments until a DTC is set.

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

VREF is a consistent positive voltage (approximately 5.0 volts +/- 10%) that is provided by the powertrain control module (PCM). This voltage is typically used by 3-wire sensors. SIG RTN is a dedicated return path for VREF applied components.

Note. Enter this pinpoint test only when a check for VREF has failed in the sensor pinpoint tests for 3-wire sensors and actuators. Refer to SYSTEM WIRING DIAGRAMS for the specific sensors and pin locations connected to VREF.

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

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

This pinpoint test is intended to diagnose only the following

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

Signal Functions

The CPP switches indicate the state of the clutch pedal. CPP switch A is a normally open switch that indicates clutch disengagement (bottom of travel). CPP switch B is a normally closed switch that indicates clutch engagement (top of travel). The application and release of the clutch pedal disables the speed control system, the cold idle kicker, or the power take-off (PTO) system, if enabled.

Scheme 177

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

The 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. The 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 the frequency and duty cycle with software strategies.

The powertrain control module (PCM) uses the CKP and camshaft position (CMP) signals to calculate the 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.

This pinpoint test is intended to diagnose the following

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

Scheme 178

The 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 the fuel quantity during acceleration until a specified boost pressure is obtained.

Dynamic Injection Timing - Optimizes injection timing for the 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 causes 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.

Scheme 179

The IAT 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 measures temperature.

The IAT sensor's primary function is to measure the 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.

Scheme 180

Circuit Functions

The 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 measures temperature.

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

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

Scheme 181

The 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 causes 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 the barometric pressure.

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

Scheme 182

Signal Function

The PBA 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.

Scheme 183

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

The 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 exhaust gas recirculation (EGR) monitor.

The current PCM implementation contains a mass airflow interface, which consists of a 2-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 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.

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

This pinpoint test is intended to diagnose the following

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

Scheme 184

The ECT sensor is a thermistor-type 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 limits 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 engine cover. The PCM supplies a 5-volt reference signal that the ECT sensor uses to produce an analog voltage, indicating the 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 ignores the ECT signal and substitutes the EOT signal. If both the ECT and EOT signals are out of range, the PCM assumes an engine coolant temperature of -34°C (-29°F) for starting and 82°C (180°F) for engine running conditions.

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

TEMPERATURE VS. RESISTANCE VALUES (APPROXIMATE)

The 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 indicates the oil 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 determined by the engine oil temperature.

Detection/Management

An EOT sensor signal that is detected out of range (high or low) by the PCM causes 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 lamp remains illuminated as long as the fault condition exists.

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

TEMPERATURE VS. RESISTANCE VALUES (APPROXIMATE)

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. The 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 operates for approximately 20 seconds and is then commanded off by the PCM if an RPM signal is not detected.

Scheme 185

The WIF sensor is used to detect water in the fuel system and is located in the fuel conditioning module. The WIF sensor is monitored by the powertrain control module (PCM). If the PCM detects water for more than 4 minutes, it sets continuous DTC P2269 and turns on the WATER IN FUEL indicator lamp.

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

Scheme 186

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. Inspect the FICM harness for damage, chafing and correct routing within the engine compartment and around engine components. Inspect the harness connectors for corrosion, damage, proper mating, and correct pin tension.

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.

Note. FICM detected DTCs will not be transmitted if the inter-module (PCM to FICM) controller area network (CAN) is inoperative.

The fuel injection control module (FICM) is capable of detecting individual injector opens 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 allows the operator to verify operation of all injector solenoids with the engine off.

Scheme 187

Tests Procedure

1. P1 PRELIMINARY DIAGNOSIS Carry out a visual inspection. Retrieve and record any continuous and on-demand DTCs. Record the freeze frame data. Clear the DTCs. Carry out the «INJECTOR ELECTRICAL SELF-TEST (CLICK TEST)»(ref-232983-S19106006222006052300000) . Refer to . Are any DTCs retrieved? Yes No For DTCs P0261, P0264, P0267, P0270, P0273, P0276, P0279, or P0282, GO to P2 . For DTCs P0262, P0265, P0268, P0271, P0274, P0277, P0280, or P0283, GO to P4 . For DTCs P0301, P0302, P0303, P0304, P0305, P0306, P0307, or P0308, GO to P7 . For DTCs P0263, P0266, P0269, P0272, P0275, P0278, P0281, or P0284, GO to P15 . UNABLE to duplicate the condition. CHECK for a loose connection, and damaged or corroded terminals. WIGGLE the harness attempting to recreate the fault. REPAIR as necessary. REFER to «SYMPTOM CHARTS - 6.0L DIESEL»(ref-232981) if a driveability concern exists.
2. P2 DIAGNOSTIC TROUBLE CODES (DTCs) P0261, P0264, P0267, P0270, P0273, P0276, P0279, OR P0282 Possible causes: open circuit coil to coil short fuel injector FICM connector loose FICM Key OFF. Disconnect the suspect fuel injector. Visually inspect the suspect injector pins. Measure the resistance between the suspect fuel injector pins, component side as follows: Pins 1 and 2 - 0.2 to 3.0 ohms Pins 3 and 4 - 0.2 to 3.0 ohms Pins 1 and 3 - greater than 10,000 ohms Pins 1 and 4 - greater than 10,000 ohms Pins 2 and 3 - greater than 10,000 ohms Pins 2 and 4 - greater than 10,000 ohms Are the resistances within specifications? Yes No GO to P3 . INSTALL a new fuel injector in question. CLEAR the DTCs. REPEAT the self-test.
3. P3 CHECK THE FUEL INJECTOR CIRCUITS FOR AN OPEN Disconnect the FICM. Measure the resistance between the suspect fuel injector pins 1, 2, 3, and 4, harness side and the FICM connector pins, harness side. Are the resistances less than 5 ohms? Yes No INSTALL a new FICM. REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
4. P4 DIAGNOSTIC TROUBLE CODES (DTCs) P0262, P0265, P0268, P0271, P0274, P0277, P0280, OR P0283 Possible causes: circuit short to voltage circuit short to ground fuel injector FICM Key OFF. Disconnect the suspect fuel injector to simulate the opposite DTC. Carry out the Injector Electrical Self-Test. Is DTC P0261, P0264, P0267, P0270, P0273, P0276, P0279, or P0282 indicated? Yes No GO to P2 . GO to P5 .
5. P5 CHECK THE FUEL INJECTOR CIRCUITS FOR A SHORT TO GROUND Key OFF. Disconnect the FICM. Measure the resistance between the suspect injector pins 1, 2, 3, and 4, harness side and ground. Are the resistances greater than 10,000 ohms? Yes No GO to P6 . REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
6. P6 CHECK THE FUEL INJECTOR CIRCUITS FOR A SHORT TO VOLTAGE Key ON, engine OFF. Measure the voltage between the suspect injector pins 1, 2, 3, and 4, harness side and ground. Is any voltage indicated? Yes No REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test. INSTALL a new FICM. CLEAR the DTCs. REPEAT the self-test.
7. P7 CHECK FOR CONTINUOUS MEMORY FAULT DTCs Check for continuous memory DTCs. Are DTCs P0301, P0302, P0303, P0304, P0305, P0306, P0307, or P0308 present? Yes No INSPECT the valve train, pistons, and for other base engine concerns. REPAIR as necessary. REFER to ENGINE . If OK, REFER to «PERFORMANCE DIAGNOSTIC PROCEDURES»(ref-232985-S24085002442006052300000) to continue diagnosis. GO to P8
8. P8 CARRY OUT THE KOEO SELF-TEST AND THE INJECTOR ELECTRICAL SELF-TEST Carry out the KOEO and Injector Electrical self-tests. Are any DTCs present? Yes No REFER to «DIAGNOSTIC TROUBLE CODE (DTC) DESCRIPTIONS»(ref-232985-S41991792642006052300000) . GO to P9 .
9. P9 CHECK FOR KOER DTCS Carry out the KOER self-test. Are any DTCs present? Yes No REFER to «DIAGNOSTIC TROUBLE CODE (DTC) DESCRIPTIONS»(ref-232985-S41991792642006052300000) . GO to P10 .
10. P10 CHECK THE FUEL SUPPLY PRESSURE Check the fuel system pressure. Refer to «DIAGNOSTIC SUBROUTINES - 6.0L DIESEL»(ref-232985) . Is the fuel pressure within specification? Yes No GO to P11 . REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.
11. P11 CHECK FOR FUEL AERATION Carry out the «FUEL AERATION TEST»(ref-232985-S39406171352006052300000) . Is the fuel aerated? Yes No REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test. GO to P12 .
12. P12 CHECK FOR OIL AERATION Carry out the Oil Aeration Test. Refer to «DIAGNOSTIC SUBROUTINES - 6.0L DIESEL»(ref-232985) . Is the oil aerated? Yes No CHANGE the oil. REPEAT the Oil Aeration Test. If oil aeration is present again, REFER to ENGINE . GO to P13 .
13. P13 CARRY OUT THE INJECTOR ENHANCED DIAGNOSTICS Carry out «INJECTOR INTERRUPT FOR ENHANCED DIAGNOSTICS»(ref-232985-S15703435622006052300000) . Refer to . Is a weak cylinder identified? Yes No If all 4 cylinders on one bank are identified, CHECK the following: Oil rail check valve for restriction Fuel inlet check valve FICM Compression/head gaskets Fuel contamination If multiple or individual cylinders are identified, CHECK the dual mass flywheel. If individual cylinders are identified, CHECK the following: Wiring to the injector Injector hold-down bolt Injector copper gasket presence Faulty injector If the 2 rear cylinders are identified on either bank as weak, CHECK the following: AWA fitting in the oil rail Compression/head gasket Any individual cylinder concern can be seen in the conditions listed above. If any two adjacent cylinders are identified as weak, CHECK the compression/head gasket. GO to P14 .
14. P14 CHECK THE CRANKCASE PRESSURE Carry out the «CRANKCASE PRESSURE TEST»(ref-232985-S41936086192006052300000) . Is the crankcase pressure greater than specification? Yes No REPAIR as necessary. REFER to ENGINE . INSTALL a new PCM. CLEAR the DTCs. REPEAT the self-test.
15. P15 DTCs P0263, P0266, P0269, P0272, P0275, P0278, P0281, OR P0284: CHECK THE FUEL SYSTEM PRESSURE Check the fuel system pressure. Refer to «ELECTRIC FUEL PUMP PRESSURE»(ref-232985-S29486071042006052300000) . Is the fuel pressure within specification? Yes No GO to P16 . REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.
16. P16 CRANKCASE AND COMPRESSION TESTS Carry out the «CRANKCASE PRESSURE TEST»(ref-232985-S41936086192006052300000) . Carry out a cylinder compression test on the suspect cylinder. Are any concerns present? Yes No REPAIR as necessary. REFER to ENGINE . GO to P17 .
17. P17 CARRY OUT A VISUAL INSPECTION Carry out a visual inspection for the following mechanical concerns: pushrods rocker arms valves valve springs Are any concerns present? Yes No REPAIR as necessary. REFER to ENGINE . INSPECT the fuel injector and O-rings. If the fuel injector and O-rings are OK, INSTALL a new fuel injector. CLEAR the DTCs. REPEAT the self-test.

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

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 lamp (MIL) is illuminated and the PCM functions 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.

Scheme 188

The IPR is a pulse width modulated (PWM) variable position valve that regulates the 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% depending upon the desired injection control pressure.

Scheme 189

An open or short to ground in the IPR control circuit can be detected by an on-demand output circuit check carried out during the key on engine off (KOEO) self-test. An injection control pressure step test, in which the PCM commands and then measures specific preprogrammed pressures is carried out during the key on engine running (KOER) self-test.

The PCM is also capable of detecting whether the 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. The engine will not operate with an IPR circuit that is not functioning.

Scheme 190

1. R1 PRELIMINARY DIAGNOSIS FOR DTC P2623 NOTE: The DTC will not set during crank mode. Carry out a visual inspection. Retrieve and record all DTCs. Record the freeze frame data. Clear all DTCs. Carry out the on-demand self-test. Is DTC P2623 present? Yes No GO to R2 . UNABLE to duplicate the condition. CHECK for a loose connection, and damaged or corroded terminals. WIGGLE the harness attempting to recreate the fault. REPAIR as necessary. REFER to «SYMPTOM CHARTS - 6.0L DIESEL»(ref-232981) if a driveability concern exists.
2. R2 CHECK THE IPR SOLENOID RESISTANCE Key OFF. Disconnect the IPR. Measure the resistance between the IPR solenoid pin 1, component side and the IPR solenoid pin 2, component side. Is the resistance between 3.0 and 15.0 ohms? Yes No GO to R3 . INSTALL a new IPR. CLEAR the DTCs. REPEAT the self-test.
3. R3 CHECK THE IPR SOLENOID VOLTAGE Key ON, engine OFF. Measure the voltage between the IPR solenoid VPWR circuit pin 1, harness side and ground. Is the voltage greater than 10.5 volts? Yes No GO to R4 . REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
4. R4 CHECK THE IPR CONTROL CIRCUIT FOR A SHORT TO POWER Key OFF. Disconnect the PCM engine connector. Key ON, engine OFF. Measure the voltage between the IPR solenoid control circuit pin 2, harness side and ground. Is any voltage indicated? Yes No REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. GO to R5 .
5. R5 CHECK THE IPR CONTROL CIRCUIT FOR A SHORT TO GROUND Key OFF. Measure the resistance between the IPR solenoid control circuit pin 2, harness side and ground. Is the resistance greater than 10,000 ohms? Yes No GO to R6 . REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
6. R6 CHECK THE IPR CONTROL CIRCUIT FOR AN OPEN Measure the resistance between the PCM engine connector pin 2, harness side and the IPR solenoid control circuit pin 2, harness side. Is the resistance less than 5 ohms? Yes No INSTALL a new PCM. CLEAR the DTCs. REPEAT the self-test. REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test

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

Fault/Management

When the FICM continuously receives less than 7 volts or more than 16 volts, DTC P1378 or P1379 are 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.

Scheme 191

The 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 passes the sensor once per camshaft revolution and produces a single pulse correspondingly. The camshaft speed is calculated from the frequency of the CMP sensor signal. Diagnostic information on the CMP input signal is obtained by carrying out accuracy checks on signal levels, frequency, and duty cycle with software strategies.

The powertrain control module (PCM) requires a crankshaft position (CKP) sensor and CMP signal to calculate engine speed and piston position. The CMP sensor creates a signal that the PCM uses to indicate the left or right bank. The engine will not operate without a CMP signal.

An inactive CMP signal during cranking is detectable by the PCM. An inactive CMP signal causes 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 is set.

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

The 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 2 components, a valve with an 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 indicates the position of the EGR valve.

The PCM detects 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 carrying out the output state low test while monitoring the exhaust gas recirculation position (EGRP) percentage.

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

Scheme 192

The EP sensor is a variable capacitance sensor. A 5-volt reference signal from the powertrain control module (PCM) is used by the EP sensor to produce a linear analog voltage signal indicating the 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 closes and the PCM defaults the VGT to calculated reference values.

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

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+ switch with the system on and a vehicle speed greater than 40 km/h (25 mph) activates the system. Tapping the SET+ or SET- switches increases or decreases the vehicle speed by 1.6 km/h (1 mph) per tap. If the respective switch is pressed and held, the vehicle speed accelerates or decelerates until the switch is released. Pressing and releasing the OFF switch or turning the ignition switch to the OFF position deactivates the system. Standby mode is achieved with the application of the brake pedal. Pressing the RESUME switch with the system in standby mode increases 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.

Scheme 193

The powertrain control module (PCM) stores the vehicle operating conditions in keep alive memory (KAM) and uses 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.

Scheme 194

The APP sensor provides 3 independent input signals to the powertrain control module (PCM) indicating the driver's demand for power and is based upon the rotation angle of the pedal. The PCM determines the APP position by processing and uses the input signals to calculate the desired fuel quantity, injection timing, and the correct injection control pressure.

Any detected malfunction of the APP sensor illuminates the electronic throttle control (wrench) indicator. A PCM detected fault on one of the 3 sensor signals will permit normal operation. A fault with 2 sensor signals only allows the engine to operate at idle.

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

Scheme 195

Scheme 196

Scheme 197

Note. Base idle should not be less than 0.5 volt.

The 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 results 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 the fan speed. Fan speed is measured through a Hall effect sensor, and is monitored by the PCM during closed loop operation.

The PCM optimizes the fan speed based on the 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 monitors the fan speed through the Hall effect sensor. If a fan speed increase is required, the PCM outputs the PWM signal to the fluid port, providing the required fan speed increase.

During the KOER self-test, the PCM commands a 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.

The 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 power take-off (PTO) system (if equipped).

Scheme 198

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

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

Scheme 199

The PTO system provides an input signal to the powertrain control module (PCM) indicating there is an additional load being applied to the engine. The PCM disables the on-board diagnostic (OBD) monitors and increases the engine RPM based on the PTO system or auxiliary idle control input.

The following entry conditions are required to enable the PTO or auxiliary idle control

1. accelerator pedal released
2. automatic transmission in PARK or manual transmission in NEUTRAL with the clutch pedal released
3. brake pedal released
4. engine at normal operating temperature
5. parking brake applied

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

The injector control pressure (ICP) is controlled by the injection pressure regulator (IPR). 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 switch is in the ON position. The valve position is controlled by switching the output signal circuit to ground. The ON/OFF time is modulated from 0% to 65%, depending upon the desired control pressure.

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.

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 increases 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 or higher commanded ICP to achieve idle. A below 16% indicates low effort to achieve idle.

The PCM is capable of detecting whether the 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 is 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. The engine will not operate with an IPR circuit that is not functioning.

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

The primary function of the ICP sensor is to provide a feedback signal to indicate the oil rail pressure so the PCM can command the correct injector timing, pulse width, and 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 lamp (MIL) is illuminated and the PCM functions 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.

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

The PCM monitors the ICP sensor signal to control the injection pressure regulator (IPR) duty cycle. The PCM modulates 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 lamp (MIL) is illuminated and the PCM functions 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.

Scheme 200

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 the crankshaft position and the camshaft sensor signal information to determine which cylinder misfired.

The misfire detection monitor is 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 sets a random misfire DTC.

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

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

Scheme 201

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 the 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 the engine RPM. In the event that the engine RPM does exceed the DEPM limit, the DEPM disables the crankshaft and camshaft output signals sent by the PCM to the FICM.

The fuel injection control module monitor (FICMM) input line informs the diesel engine power monitor (DEPM) when the injectors are turned on and 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 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.

Scheme 202

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.

The 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 measures temperature.

The 6.0L diesel uses 2 IAT sensors. For vehicles with a mass air flow (MAF) sensor, the IAT sensor is integrated into the MAF sensor. For vehicles without a MAF sensor, the IAT sensor is a stand alone 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 the IAT2 signal to IAT signal 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 BPA switch provides a backup signal for the brake pedal position (BPP) switch. If the BPP switch signal is lost, the BPA switch provides 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.

Scheme 203

The low idle engine speed is between 600 and 750 RPM. The EGR valve position is greater than.08 volts. The mass fuel desired (MFDES) is between 4 and 16mg/stk, at low idle for a minimum of 30 seconds. No EP, BAP, MAP, pressure signal, IAT, IAT2 temperature signal, VDF fan P0480, or EGR related faults. Fault condition: IAT2 exceeds a calibrated temperature for more than 30 seconds, based on IAT temperature.

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

The anti-lock brake system (ABS) module provides the vehicle speed signal to the powertrain control module (PCM). The vehicle speed signal is used by the PCM to calculate cruise control and power take-off control strategies.

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

Scheme 204

The variable geometry turbocharger (VGT) is controlled by the powertrain control module (PCM). The PCM uses 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 the 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.

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.

The PCM receives the FLI message through the controller area network (CAN) from the instrument cluster. The FLI message is one of several required inputs used by the PCM to enable the misfire detection monitor.