The crankshaft position (CKP) sensor signal indicates the crankshaft speed and position. The CKP sensor is connected directly to the Powertrain Control Module (PCM), and consists of the following circuits
- The 12-volt reference circuit.
- The low reference circuit.
- The CKP sensor signal circuit.
If the PCM detects that the CKP sensor signal is inconsistent for 120 seconds, DTC P0336 sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 2 This step verifies that the malfunction is present.
- 3 This step inspects for electromagnetic interference (EMI) on the CKP sensor circuits.
Scheme 564
Scheme 565
The camshaft position (CMP) sensor works in conjunction with a 1 X reluctor wheel on the camshaft. The Powertrain Control Module (PCM) provides a 12-volt reference to the CMP sensor as well as a low reference and a signal circuit.
As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor. The sensors internal circuitry detects this and produces a signal which the PCM reads.
The CMP uses this 1 X signal is used by the PCM to determine if the cylinder is at Top Dead Center (TDC) is on the firing stroke or the exhaust stroke. The PCM can determine TDC for all cylinders by using the CKP sensor 24 X signal alone. The engine will start without a CMP signal as long as the PCM receives the CKP sensor 24 X signal. A slightly longer cranking time may be a symptom of this condition. The system attempts synchronization and looks for an increase in engine speed indicating that the engine started. If the PCM does not detect an increase in engine speed, the PCM assumes that the PCM incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position. If the PCM detects that a CMP to CKP mis-match has occurred DTC P0341 sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 3 This step inspects for electromagnetic interference (EMI) on the CMP sensor circuits.
- 6 Damage to the face of the sensor could indicate foreign material passing between the CMP sensor and the reluctor wheel. This condition would cause this DTC to set. Damage to the reluctor wheel would affect the CMP sensor output.
Scheme 566
The camshaft position (CMP) sensor works in conjunction with a 1 X reluctor wheel on the camshaft. The Powertrain Control Module (PCM) provides a 12 volt reference to the CMP sensor as well as a low reference and a signal circuit.
As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor. The sensors internal circuitry detects this and produces a signal which the PCM reads.
The CMP sensor 1 X signal is used by the PCM to determine if the cylinder at Top Dead Center (TDC) is on the firing stroke or the exhaust stroke. The PCM can determine TDC for all cylinders by using the CKP sensor 24 X signal alone. The engine will start without a CMP signal as long as the PCM receives the CKP sensor 24 X signal. A slightly longer cranking time may be a symptom of this condition. The system attempts synchronization and looks for an increase in engine speed indicating that the engine started. If the PCM does not detect an increase in engine speed, the PCM assumes that the PCM incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position. If the PCM detects that a CMP signal is constantly low, DTC P0342 sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 5 This step tests the CMP sensor signal circuit. Applying a voltage causes the CMP sensor high to low and low to high parameter to increase if the circuit and the PCM are operating properly.
Scheme 567
Scheme 568
The camshaft position (CMP) sensor works in conjunction with a 1 X reluctor wheel on the camshaft. The Powertrain Control Module (PCM) provides a 12-volt reference to the CMP sensor as well as a low reference and a signal circuit.
The CMP sensor determines whether a cylinder is on a firing stroke or on an exhaust stroke. As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor. The sensors internal circuitry detects this and produces a signal which the PCM reads.
The CMP sensor 1 X signal is used by the PCM to determine if the cylinder at Top Dead Center (TDC) is on the firing stroke or the exhaust stroke. The PCM can determine TDC for all cylinders by using the CKP sensor 24 X signal. A slightly longer cranking time may be a symptom of this condition. The system attempts synchronization and looks for an increase in engine speed indicating that the engine started. If the PCM does not detect an increase in engine speed, the PCM assumes that the PCM incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position. If the PCM detects that the CMP signal is constantly high, DTC P0343 sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 5 This step tests the CMP sensor signal circuit. Applying a voltage causes the CMP sensor high to low and low to high parameter to increase if the circuit and the PCM are operating properly.
Scheme 569
Scheme 570
The ignition system on this engine uses an individual ignition coil for each cylinder. The Powertrain Control Module (PCM) controls the ignition system operation. The PCM controls each coil using one of 8 Ignition Control (IC) circuits. The PCM commands the IC circuit low when a spark event is requested. This causes the IC module to energize the ignition coil to create a spark at the spark plug. Each ignition coil has the following circuits
- The Ignition Control (IC) circuit.
- The ignition 1 voltage circuit.
- A ground circuit.
- A reference low circuit.
The sequencing and timing are PCM controlled. This DTC sets when the IC circuit is out of range.
The numbers below refer to the step numbers in the diagnostic procedure.
- 3 This step verifies the integrity of the IC circuit and the PCM output.
- 4 This step tests for a short to ground on the IC circuit.
Scheme 571
Scheme 572
The Powertrain Control Module (PCM) tests the Exhaust Gas Recirculation (EGR) system during deceleration. The PCM does this by momentarily commanding the EGR valve to open while monitoring the signal circuit of the Manifold Absolute Pressure (MAP) sensor. When the EGR valve is opened, the PCM will expect to see a predetermined increase in MAP. If the expected increase in MAP is not detected, the PCM records the amount of MAP difference that was detected and adjusts a calibrated fail counter towards a calibrated fail threshold level. The number of EGR flow test counts required to exceed the fail threshold may vary according to the amount of detected EGR flow error.
Normally, the PCM will only allow one EGR flow test during an ignition cycle. TO aid in verifying a repair, the PCM will allow up to 13 EGR flow test counts during the first ignition cycle following a code clear event. Between 8-13 EGR flow test counts should be sufficient for the PCM to determine adequate EGR flow and pass the EGR flow test. If the PCM detects an EGR flow error, DTC P0401 sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 2 MAP sensor faults must be diagnosed first. A skewed MAP sensor reading could cause this DTC to set.
Scheme 573
The Powertrain Control Module (PCM) monitors the EGR position sensor parameter of the Exhaust Gas Recirculation (EGR) valve to ensure that the valve responds properly to commands from the PCM. The PCM compares the EGR position sensor parameter with the desired EGR position parameter when the valve is commanded open. If the PCM detects a difference of 12 percent between the EGR position sensor parameter and desired EGR position parameter for a calibrated amount of time, DTC P0404 will set.
The Exhaust Gas Recirculation (EGR) valve position sensor is monitored by the Powertrain Control Module (PCM). The 5-volt reference circuit, low reference circuit and the EGR valve position signal circuit are used by the PCM to determine the EGR valve position. If the EGR valve position sensor signal voltage is pulled below a calibrated value, DTC P0405 sets.
The engine systems uses a 3-way catalytic converter (TWC) to control emissions of Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides Of Nitrogen (NOx). The catalyst within the TWC promotes a chemical reaction, which oxidizes the HC and CO that are present in the exhaust system. This reaction converts these chemicals into harmless water vapor and carbon dioxide. The catalyst also reduces the NOx which converts into nitrogen. The Powertrain Control Module (PCM) monitors this process using Heated Oxygen Sensors (HO2S) bank 1 sensor 2 and HO2S bank 2 sensor 2, which are located in the exhaust stream past the TWC. These sensors are referred to as catalyst monitor sensors. The catalyst monitor sensors produce an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalysts ability to effectively convert the exhaust emissions. If the catalyst is functioning correctly, the catalyst monitor signals will be far less active than that of the signals which are produced by the fuel control HO2S 1 bank 1 and fuel control HO2S bank 2. This indicates that the TWC oxygen storage capacity is at an acceptable threshold. When the response time of the catalyst monitors are close to that of the fuel control sensors, the ability of the catalyst to store oxygen is considered to be below an acceptable threshold. If the PCM detects this condition, DTC P0420 catalyst low efficiency for bank 1 or DTC P0430 catalyst low efficiency for bank 2 sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 6 This step inspects for conditions than can cause the 3-way catalytic converter efficiency to appear degraded.
- 8 A catalytic converter which has been discolored may be due to an engine running rich, lean or had a previous severe misfire. Verifying the fuel trim percentages may be of assistance in determining if such a condition exists.
Scheme 574
Scheme 575
This diagnostic tests the Evaporative Emission (EVAP) system for a small leak when the key is turned OFF and the correct conditions are met.
Heat is transferred into a vehicle fuel tank while the vehicle is operating. When the vehicle is turned OFF, a change in the fuel tank vapor temperature occurs, which may result in corresponding pressure changes in the fuel vapor space. This change is monitored by the control module using the fuel tank pressure sensor input. The control module then makes a judgement on the integrity of the system. With a 0.020 inch (0.51 mm) leak in the system, the amount of pressure change observed is significantly less than that of a sealed system.
If the control module detects a pressure change less than a calibrated amount, DTC P0442 sets.
The numbers below refer to the step number in the diagnostic procedure.
- 3 Introducing smoke in 15 second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
- 5 This step verifies that repairs are complete and that no other condition is present.
Scheme 576
Scheme 577
An ignition voltage is supplied directly to the Evaporative (EVAP) emission canister purge valve. The EVAP canister purge valve is pulse width modulated (PWM). The scan tool displays the amount of ON time as a percentage. The control module monitors the status of the driver. The control module controls the EVAP canister purge valve ON time by grounding the control circuit via an internal switch called a driver. If the control module detects an incorrect voltage for the commanded state of the driver, this DTC sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 2 This step tests if the concern is active. The EVAP purge valve is PWM. You should hear a clicking sound when the purge valve is commanded to 50 percent. The clicking sound should stop when the EVAP purge valve is commanded to 0 percent. The rate at which the valve cycles should increase when the commanded state is increased, and decrease when the commanded state is decreased. Repeat the commands as necessary.
- 5 This step verifies that the control module is providing ground to the EVAP purge valve.
- 6 This step tests if a ground is constantly being applied to the EVAP purge valve.
Scheme 578
Scheme 579
This DTC tests the Evaporative Emission (EVAP) system for a restricted or blocked EVAP vent path. The control module commands the EVAP canister purge solenoid ON and the EVAP canister vent solenoid ON. This allows vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the EVAP canister purge solenoid OFF and the EVAP canister vent solenoid OFF. The control module monitors the Fuel Tank Pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 inches H2O in a calibrated time, this DTC sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 3 This test determines if the failure is present or intermittent.
Scheme 580
Scheme 581
An ignition voltage is supplied to the Evaporative Emission (EVAP) canister vent valve. The control module grounds the EVAP canister vent valve control circuit to close the valve be means of an internal switch called a driver. The scan tool displays the commended state of the EVAP canister vent valve as ON or OFF. The control module monitors the status of the driver. If the control module detects an incorrect voltage for the commanded state of the driver, this DTC sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 2 A click should be heard or felt when the valve operates. Ensure that both the ON and the OFF states are commanded. Repeat the commands as necessary.
- 5 This step verifies that the control module is providing ground to the EVAP vent valve.
- 6 This step tests if the EVAP vent valve control circuit is grounded.
Scheme 582
Scheme 583
The Fuel Tank Pressure (FTP) sensor measures the difference between the air pressure or vacuum in the evaporative emission (EVAP) system, and the outside pressure. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. If the FTP sensor signal voltage goes below a calibrated value, this DTC sets.
If FTP sensor signal voltage is 1.5 volts or more the FTP has negative pressure/vacuum. If the FTP sensor signal voltage is 1.5 volts or less the FTP has positive pressure.
The number below refers to the step number in the diagnostic procedure.
- 5 This step tests for the proper operation of the circuit in the high voltage range.
- 6 The 5-volt reference circuit for the FTP sensor is routed through connector C152. This area may provide a good test point for diagnosing concerns with this circuit.
- 7 The FTP sensor signal circuit is routed through connector C152. This area may provide a good test point for diagnosing concerns with this circuit.
Scheme 584
Scheme 585
The Fuel Tank Pressure measures the difference between the air pressure or vacuum in the Evaporative Emission (EVAP) system, and the outside air pressure. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal circuit voltage varies depending on EVAP system pressure or vacuum. If the FTP sensor signal voltage increases above a calibrated value, this DTC sets.
If FTP sensor signal voltage is 1.5 volts or more the FTP has negative pressure/vacuum. If the FTP sensor signal voltage is 1.5 volts or less the FTP has positive pressure.
The number below refers to the step number in the diagnostic procedure.
- 2 If DTC P0641 or P0651 is set, the 5-volt reference circuit maybe shorted to a voltage.
Scheme 586
Scheme 587
The control module tests the Evaporative Emission (EVAP) system for a large leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the EVAP system vacuum level. When the conditions for running are met, the control module commands the EVAP canister purge valve OPEN and the EVAP vent valve CLOSED. This allows engine vacuum to enter the EVAP system. At a calibrated time, or vacuum level, the control module commands the EVAP canister purge valve closed, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum level. If the system is unable to achieve the calibrated vacuum level, or the vacuum level decreases too rapidly, this DTC sets.
The number below refers to the step number in the diagnostic procedure.
- 3 Introducing smoke in 15 second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
- 5 This step verifies proper operation of the Fuel Tank Pressure (FTP) sensor.
- 6 A normal operating FTP sensor should increase above 5 inches of H2O and stop between 6 and 7 inches of H2O.
Scheme 588
Scheme 589
Scheme 590
This DTC tests for undesired intake manifold vacuum flow to the Evaporative Emission (EVAP) system. The control module seals the EVAP system by commanding the EVAP canister purge valve OFF and the EVAP canister vent valve ON. The control module monitors the Fuel Tank Pressure (FTP) sensor to determine if a vacuum is being drawn on the EVAP system. If vacuum in the EVAP system is more than a predetermined time, this DTC sets.
If the control module command is ON the EVAP purge valve is OPEN and the EVAP canister vent valve is CLOSED. If the control module command is OFF the EVAP purge valve is CLOSED and the EVAP canister vent valve is OPEN.
The Throttle Actuator Control (TAC) system uses vehicle electronics and components to calculate and control the position of the throttle plate. In order to decrease idle speed the TAC system closes the throttle plate reducing airflow into the engine. In order to increase idle speed the TAC system opens the throttle plate allowing more airflow into the engine. If the actual idle RPM does not match the desired idle RPM within a calibrated time, this DTC set.
The number below refers to the step number in the diagnostic procedure.
- 2 This test determines if the engine can achieve the commanded RPM. If the engine does not reach the commanded RPM, the test determines whether the RPM is too high or too low.
Scheme 591
This diagnostic applies to internal microprocessor integrity conditions within the Powertrain Control Module (PCM). This diagnostic also addresses if the PCM is not programmed.
The numbers below refer to the step numbers in the diagnostic procedure.
- 2 A DTC P0602 indicates the PCM is not programmed.
Scheme 592
The Powertrain Control Module (PCM) provides 5 volts to the following sensors
- The Engine Oil Pressure (EOP) sensor.
- The Exhaust Gas Recirculation (EGR) valve.
- The Manifold Absolute Pressure (MAP) sensor.
These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the PCM. Therefore a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The PCM monitors the voltage on the 5-volt reference circuit. If the PCM detects that the voltage is out of tolerance, DTC P0641 sets.
The Malfunction Indicator Lamp (MIL) is located on the Instrument Panel Cluster (IPC). The MIL informs the driver than an emission system fault has occurred and that the engine control system requires service. The control module monitors the MIL control circuit for conditions that are incorrect for the commanded state of the MIL. For example, a failure condition exists if the control module detects low voltage when the MIL is commanded OFF, or high voltage when the MIL is commanded ON. If the control module detects an improper voltage on the MIL control circuit, DTC P0650 will set.
The numbers below refer to the step numbers in the diagnostic procedure.
- 4 This step tests for a short to ground in the MIL control circuit. With the Powertrain Control Module (PCM) disconnected and the ignition ON, the MIL should be OFF.
- 5 This step tests for a short to voltage on the MIL control circuit. With the fuse removed, there should be no voltage on the MIL control circuit.
Scheme 593
Scheme 594
The Powertrain Control Module (PCM) provides 5 volts to the following sensors
- The Air Conditioning (A/C) pressure sensor.
- The Fuel Tank Pressure (FTP) sensor, if equipped.
These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the PCM. Therefore a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The PCM monitors the voltage on the 5-volt reference circuit. The PCM detects that the voltage is out of tolerance, DTC P0651 sets.
The Malfunction Indicator Lamp (MIL) requests circuit signals the Engine Control Module (ECM) that the Transmission Control Module (TCM) is requesting MIL illumination.
The numbers below refer to the step numbers in the diagnostic procedure.
- 2 If the TCM has DTCs set that are requesting MIL illumination, those DTCs must be diagnosed first.
Scheme 595
The Transmission Control Module (TCM) Malfunction Indicator Lamp (MIL) request circuit signals the Powertrain Control Module (PCM) that the TCM is requesting MIL illumination.
The Manifold Absolute Pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits
- 5-volt circuit.
- Low reference circuit.
- MAP sensor signal circuit.
The Powertrain Control Module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The PCM should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a Wide Open Throttle (WOT). The MAP sensor is also used in order to determine the Barometric Pressure (BARO). This occurs when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range. If the PCM detects a MAP sensor signal voltage that is intermittently high, DTC P1106 sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 3 This step attempts to pinpoint the location of the intermittent fault.
Scheme 596
The Manifold Absolute Pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits
- 5-volt reference circuit.
- Low reference circuit.
- MAP sensor signal circuit.
The Powertrain Control Module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The PCM should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a Wide Open Throttle (WOT). The MAP sensor is also used in order to determine the Barometric Pressure (BARO). This occurs when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range. If the PCM detects a MAP sensor signal voltage that is intermittently low, DTC P1107 sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 3 This step attempts to pinpoint the location of the intermittent t fault.
Scheme 597
The Intake Air Temperature (IAT) sensor is a variable resistor, sometimes called a thermistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The Powertrain Control Module (PCM) supplies 5 volts to the IAT signal circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance lowers. With high sensor resistance, the PCM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the IAT signal circuit. If the PCM detects an intermittent high IAT signal voltage, indicating a low temperature, DTC P1111 sets.
The Intake Air Temperature (IAT) sensor is a variable resistor, sometimes called a thermistor. The IAT sensor has a signal circuit and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The Powertrain Control Module (PCM) supplies 5 volts to the IAT signal circuit. When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor resistance lowers. With high sensor resistance, the PCM detects a high voltage on the IAT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the IAT signal circuit. If the PCM detects an intermittent low IAT signal voltage, indicating a high temperature, DTC P1112 sets.
The Engine Coolant Temperature (ECT) sensor is a variable resistor, sometimes called a thermistor, that measures the temperature of the engine coolant. The Powertrain Control Module (PCM) supplies 5 volts to the ECT signal circuit. When the ECT is cold, the sensor resistance is high. When the ECT increases, the sensor resistance lowers. With high sensor resistance, the PCM detects a high voltage on the ECT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the ECT signal circuit. If the PCM detects an excessively low ECT signal voltage, which is a high temperature indication, this Diagnostic Trouble Code (DTC) will set.
The Engine Coolant Temperature (ECT) sensor is a variable resistor, sometimes called a thermistor, that measures the temperature of the engine coolant. The Powertrain Control Module (PCM) supplies 5 volts to the ECT signal circuit. When the ECT is cold, the sensor resistance is high. When the ECT increases, the sensor resistance lowers. With high sensor resistance, the PCM detects a high voltage on the ECT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the ECT signal circuit, if the PCM detects an excessively high signal voltage, which is a low temperature indication, this Diagnostic Trouble Code (DTC) will set.
The Accelerator Pedal Position (APP) sensor is mounted on the accelerator pedal assembly. The sensor is actually 2 individual APP sensors within 1 housing. Two separate signal circuits are used in order to connect the accelerator pedal sensor assembly, and the Throttle Actuator Control (TAC) module
- A 5-volt reference circuit.
- A low reference circuit.
- A signal circuit.
If only 1 APP sensor DTC is set, the redundant APP systems allow the TAC system to continue operating normally. This DTC sets if the Powertrain Control Module (PCM) detects a condition with more than 1 APP sensor. One APP sensor DTC will not cause the Reduced Engine Power message to be displayed. 2 APP sensor DTCs for the same sensor also will not cause the Reduced Engine Power message to be displayed. However, if two or more DTCs are set involving more than 1 APP sensor, this DTC will set and the Reduced Engine Power message is displayed.
The number below refer to the step number in the diagnostic procedure.
- 2 When the problems are corrected which are causing the APP sensor DTCs to set, the status of this DTC will change to history.
Scheme 598
Heated Oxygen Sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compared the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The Powertrain Control Module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV. When the engine is first started the PCM operates in open loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and closed loop is achieved, the HO2S generates a voltage within a range of 0-1000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream. This diagnostic will only run once per ignition cycle. The PCM monitors the number or rich-to-lean and lean-to-rich transitions. A transition is defined as, the HO2S voltage changes from above 600 mV to below 250 mV or from below 250 mV to above 600 mV. If the PCM detects that the number or transitions were less than a specified value, DTCs P1133 or P1153 will set.
The numbers below refer to the step numbers in the diagnostic procedure.
- 2 If the voltage is varying above and below the specified value, the condition is not present.
Scheme 599
Scheme 600
The secondary fuel pump is located in the rear fuel tank. The secondary fuel pump is powered by a secondary fuel pump relay. Fuel is transferred from the rear fuel tank to the front fuel tank in order to ensure all of the usable fuel volume is available to the primary fuel pump. The secondary fuel pump relay supply voltage is received from the primary fuel pump relay when the primary fuel pump is energized. The Diagnostic Trouble Code (DTC) sets when the Powertrain Control Module (PCM) commands the secondary fuel pump ON and a predetermined change in both the front and rear fuel level sensors does not occur.
The numbers below refer to the step numbers in the diagnostic procedure.
- 2 This step tests the supply voltage circuit of the secondary fuel pump relay.
- 4 This step verifies the secondary fuel pump operation. Listen for an audible sound as the secondary fuel pump relay harness connector is jumpered.
- 5 This step verifies that there is adequate fuel in the rear fuel tank. The rear fuel tank sensor voltage must be above 1 volt in order to continue.
- 7 This step tests the secondary fuel pumps ability to transfer fuel. The rear fuel level sensor voltage should decrease while the secondary fuel pump is ON.
- 8 This step tests for a short to ground on the control circuit of the secondary fuel pump relay. If the test lamp illuminates, a short to ground is indicated.
- 9 This step tests for a short to voltage on the control circuit of the secondary fuel pump relay. If the test lamp illuminates, a short to voltage is indicated.
- 10 This step verifies the secondary fuel pump relay operation. An audible click should be heard as the secondary fuel pump relay control circuit is grounded. The secondary fuel pump should turn ON as the fuel pump relay control circuit is grounded.
Scheme 601
Scheme 602
Scheme 603
Scheme 604
The PCM uses the ECT sensor to monitor the engine for an over temperature condition. This condition occurs when the coolant temperature is above 270°F (132°C). When an over temperature condition is present, DTC P1258 will set. The PCM will disable two groups of four cylinders by turning OFF the fuel injectors. By switching between the two groups of cylinders, the PCM is able to reduce the temperature of the coolant.
The Powertrain Control Module (PCM) detects engine misfire events by monitoring variations in crankshaft rotation speed. Wheel speed changes caused by rough road conditions can cause changes in crankshaft speed. By monitoring the wheel speed sensors, the Anti-Lock Brake System (ABS) can determine if the vehicle is operating on a rough road. If the ABS is detecting a rough road condition severe enough to effect misfire detection, a rough road signal is sent to the PCM on the serial data circuit. If DTC P0300 is set and the rough road information is not available due to an ABS malfunction, DTC P1380 will set.
The Powertrain Control Module (PCM) detects engine misfire events by monitoring variations in the crankshaft rotation speed. Wheel speed changes caused by rough road conditions can cause changes in crankshaft speed. By monitoring the wheel speed sensors, the Anti-Lock Brake System (ABS) can determine if the vehicle is operating on a rough road. If the ABS is detecting a rough road condition severe enough to effect misfire detection, a rough road signal is sent to the PCM on the serial data circuit. If DTC P0300 is set and the rough road information is not available due to and ABS malfunction, DTC P1381 will set.
The number below refers to the step number in the diagnostic procedure.
- 1 This step will diagnose a malfunction in the serial data circuits.
Scheme 605
The Powertrain Control Module (PCM) monitors the Exhaust Gas Recirculation (EGR) valve pintle position input to ensure that the valve responds properly to commands from the PCM. When the ignition switch is turned ON, the PCM learns the EGR learned minimum position. The PCM compares the EGR learned minimum position to the EGR position sensor when the EGR valve is commanded closed. If the EGR position sensor indicates that the EGR valve is still open when the PCM is commanding the EGR valve closed, this DTC will set.
The numbers below refer to the step numbers in the diagnostic procedure.
- 2 This step verifies that the malfunction is present.
Scheme 606
Scheme 607
The Powertrain Control Module (PCM) uses the following readings in order to calculate the predicted Mass Air Flow (MAF) rate
- The Throttle Position (TP).
- The Barometric (BARO) pressure.
- The Intake Air Temperature (IAT).
- The engine RPM.
The PCM compares the predicted MAF value to the actual MAF value, and to the speed density calculation in order to verify the proper throttle operation.
The number below refers to the step number in the diagnostic procedure.
- 5 Locating and repairing an individual condition may correct more than 1 DTC.
Scheme 608
The commanded Throttle Position (TP), based on Accelerator Pedal Position (APP) and possibly other limiting factors, is compared to the actual TP. The 2 values should be within a calibrated range of each other. Both the Powertrain Control Module (PCM) and the Throttle Actuator Control (TAC) module redundantly monitor the commanded and actual TP. This DTC sets if the PCM detects an out-of-range condition between commanded and actual pedal position.
The numbers below refer to the step numbers in the diagnostic procedure.
- 5 If the TP indicated angle does not follow the movement of the throttle blade, and no TP sensor DTCs are set, there is a mechanical condition with the throttle shaft or the TP sensor.
- 16 Locating and repairing an individual condition may correct more than 1 DTC.
Scheme 609
Scheme 610
The predicted Throttle Position (TP), based on Accelerator Pedal Position (APP) and other limiting factors, is compared to the Actual throttle position. The 2 values should be within a calibrated range of each other. Both the Powertrain Control Module (PCM) and the Throttle Actuator Control (TAC) module redundantly monitor the predicted and actual throttle position. This DTC sets if the PCM detects an out of range condition between the predicted and actual throttle position.
The numbers below refer to the step numbers in the diagnostic procedure.
- 7 If the TP indicated angle does not follow the movement of the throttle blade, and no TP sensor DTCs are set, there is a mechanical condition with the throttle shaft or the TP sensor.
- 18 Locating and repairing an individual condition may correct more than 1 DTC.
Scheme 611
Scheme 612
The Throttle Actuator Control (TAC) module and the Powertrain Control Module (PCM) communicate via a dedicated serial data circuit. This serial data circuit is separate from any other serial data circuit on the vehicle. Accurate transmitting and receiving of serial data requires not only good circuit integrity but also adequate system voltage. This diagnostic test monitors the accuracy of the serial data transmitted between the TAC module and the PCM. If the PCM detects a loss of data or invalid data, this DTC sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 2 This step determines if the IGN relay is supplying a voltage to the ETC fuse.
- 5 Increasing the engine speed to 3000 RPM aids in locating a shorted throttle actuator motor control circuit. Depending on the polarity of the throttle actuator motor transistors, this DTC may not set with a fault in the control circuits. The throttle actuator motor is a bi-directional DC motor. Raising the engine speed changes the polarity of the transistors in the throttle actuator motor. This occurs because 1 set of the transistors are low, 0 volts, and the other set are high, battery voltage. Therefore, if 1 set of transistors are at a low voltage and the corresponding circuit is shorted low, DTC P1518 will not set. When the polarity of the transistors change this DTC sets. If this DTC does not Fail This ignition, continue to monitor this DTC status while moving related harnesses and connectors.
- 29 Locating and repairing an individual condition may correct more than 1 DTC.
Scheme 613
Scheme 614
Scheme 615
Scheme 616
The Throttle Actuator Control (TAC) module contains data which is essential for proper TAC system operation. The TAC module continuously tests the integrity of this data. When the TAC module is unable to write or read data to and from random access memory (RAM), or the TAC module is unable to correctly read data from the flash memory or and internal TAC module processor fault is detected, this DTC sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 4 Locating and repairing an individual condition may correct more than 1 DTC.
Scheme 617
The Accelerator Pedal Position (APP) sensor 1 is a potentiometer type sensor with the following 3 circuits
- A 5-volt reference circuit.
- A low reference circuit.
- A signal circuit.
The control module provides the APP sensor a 5-volt reference circuit and a low reference circuit. The APP sensor then provides the control module a signal voltage proportional to pedal movement. The APP sensor 1 signal voltage is low at rest and increases as the pedal is depressed. When the control module detects that the APP sensor 1 signal or APP sensor 5-volt reference voltage is outside the predetermined range, this DTC sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 12 This test isolates whether the short is to another TAC system circuit in the harness or within the TAC module.
- 26 When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
Scheme 618
Scheme 619
Scheme 620
The Accelerator Pedal Position (APP) sensor 1 is a potentiometer type sensor with the following 3 circuits
- A 5-volt reference circuit.
- A low reference circuit.
- A signal circuit.
The control module provides the APP sensor a 5-volt reference circuit and a low reference circuit. The APP sensor then provides the control module a signal voltage proportional to pedal movement. The APP sensor 1 signal voltage is low at rest and increases as the pedal is depressed. The APP sensor 2 signal voltage is also low at rest and increases as the pedal is depressed. When the control module detects that the APP sensor 1 signal and the APP sensor 2 signal circuits are out of correlation, this DTC sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 2 This step determines if a communication condition exists.
- 5 This step isolates an internal APP sensor failure. The condition may only occur at a certain accelerator pedal position. Monitoring the APP angles for sensor 2 and sensor 3 is an accurate way of verifying the actual position of the pedal. The APP angles for all 3 sensors should be within a set percent of each other. If the pedal is at rest, the APP angle for all 3 sensors should be 0 percent. If the pedal is fully depressed, all APP angles should be 100 percent.
- 6 The APP sensor 1 shares a common 5-volt reference circuit with the throttle position (TP) sensor 1. Monitoring the TP sensor 1 voltage aids in diagnosing the APP sensor 5-volt reference and low reference circuits. If the scan tool displays near 0 volts, the circuits are OK.
- 9 With the TAC module still connected, this test will help determine a short to the signal circuit either within the TAC module or wiring.
- 10 This step determines whether the TAC module or a short circuit is causing the condition.
- 19 When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set addition DTCs. Remember this if you review the stored information in Capture Info.
Scheme 621
Scheme 622
Scheme 623
The Accelerator Pedal Position (APP) sensor 2 is a potentiometer type sensor with the following 3 circuits
- A 5-volt reference circuit.
- A low reference circuit.
- A signal circuit.
The control module provides the APP sensor a 5-volt reference circuit and a low reference circuit. The APP sensor then provides the control module a signal voltage proportional to pedal movement. The APP sensor 1 signal voltage is low at rest and increases as the pedal is depressed. When the control module detects that the APP sensor 2 signal or the APP sensor 5-volt reference voltage is outside the predetermined range, this DTC sets.
The numbers below refer to the step numbers in the diagnostic procedure.
- 2 The throttle position (TP) senor 2 and the APP sensor 2 share a common 5-volt reference source. Diagnose DTC P0220 first if P0220 is also set.
- 18 This test determines whether or not the TAC module can recognize a change in signal voltage.
- 19 There are 2 separate 5-volt reference sources within the TAC module. The TP sensor 1 and APP sensor 1 share one 5-volt reference source. The TP sensor 2 and the APP sensor 2 share another common 5-volt reference source. The test determines whether the signal circuit is shorted to any one of the 5-volt reference circuits. If a short exists, the corresponding sensor voltage will be pulled low.
- 20 The previous step found the signal circuit and a 5-volt reference circuit shorted together. This test isolates whether the short is in the harness or within the TAC module.
- 26 When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
Scheme 624
Scheme 625
Scheme 626
The Throttle Position (TP) sensors 1 and 2 are potentiometer type sensors each with 3 circuits
- A 5-volt reference circuit.
- A low reference circuit.
- A signal circuit.
The TP sensor are used to determine the throttle plate angle for various engine management systems. The control module provides each TP sensor a 5-volt reference circuit and a low reference circuit. The TP sensors then provide the control module with signal voltage proportional to throttle plate movement. Both TP sensor signal voltages are low at closed throttle and increase as the throttle opens. When the control module detects that TP sensor 1 signal and TP sensor 2 signals disagree or signal voltages are outside the predetermined range, this DTC set.
The numbers below refer to the step numbers in the diagnostic procedure.
- 21 When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Remember this if you review the stored information in Capture Info.
Scheme 627
Scheme 628
See also:
• SENSOR OPERATING RANGE CHARTS - TRUCKS