Manifold Absolute Pressure (MAP) Sensor Circuit Diagram. Scheme 77
Manifold Absolute Pressure (MAP) Sensor Output Voltage - Graph. Scheme 78
General Description
The manifold absolute pressure (MAP) sensor senses manifold absolute pressure (vacuum) and converts it into electrical signals. The MAP sensor outputs low signal voltage at high-vacuum (throttle valve closed) and high signal voltage at low-vacuum (throttle valve wide open).
If a signal voltage from the MAP sensor is a set value or less, the powertrain control module (PCM) detects a malfunction and a DTC is stored.
The manifold absolute pressure (MAP) sensor senses manifold absolute pressure (vacuum) and converts it into electrical signals. The MAP sensor outputs low signal voltage at high-vacuum (throttle valve closed) and high signal voltage at low-vacuum (throttle valve wide open). If a signal voltage from the MAP sensor is a set value or more, the powertrain control module (PCM) detects a malfunction and a DTC is stored.
Two engine coolant temperature sensors and one intake air temperature sensor are used by the powertrain control module (PCM).
When the engine stops and enough time has passed, the temperature of the engine will equal the ambient temperature.
When an inappropriate temperature is detected after comparing the temperature readings of each sensor, a malfunction in the corresponding sensor is detected and a DTC is stored.
The intake air temperature (IAT) sensor is a thermistor that detects intake air temperature, and it is used for A/F feedback control to compensate for the atmospheric density fluctuations that accompany changes in intake air temperature. The IAT sensor resistance varies depending on temperature. The output voltage and the sensor resistance increase as the intake air temperature decreases. Conversely, the output voltage and the sensor resistance decrease as the intake air temperature increases. If the IAT sensor output voltage is excessively low, the powertrain control module (PCM) detects a mal-function and a DTC is stored.
The intake air temperature (IAT) sensor is a thermistor that detects intake air temperature, and it is used for A/F feedback control to compensate for the atmospheric density fluctuations that accompany changes in intake air temperature.
The IAT sensor resistance varies depending on temperature. The output voltage and the sensor resistance increase as the intake air temperature decreases. Conversely, the output voltage and the sensor resistance decrease as the intake air temperature increases. If the IAT sensor output voltage is excessively high, the powertrain control module (PCM) detects a mal-function and a DTC is stored.
The powertrain control module (PCM) supplies voltage to the engine coolant temperature (ECT) signal circuit (about 5 V) through a pull-up resistor. As the engine coolant cools, ECT sensor 1 resistance increases, and the PCM detects a high signal voltage. As the engine coolant warms, ECT sensor 1 resistance decreases, and the PCM detects a low signal voltage. If the ECT output voltage after driving a set time after starting the engine does not reach a set temperature, or when the difference between the ECT output voltage when driving and the output voltage of the ECT after the engine is stopped a set time does not change a certain amount, the PCM detects a malfunction and a DTC is stored.
Engine coolant temperature (ECT) sensor 1 is used for air/fuel ratio feedback control, ignition timing control, idle speed control, and other functions. The ECT sensor 1 resistance varies depending on the engine coolant temperature. As the engine coolant cools, the ECT sensor 1 resistance increases, and the powertrain control module (PCM) detects a high signal volt-age. As the engine coolant warms, the ECT sensor 1 resistance decreases, and the PCM detects a low signal voltage. If the ECT sensor 1 output voltage is less than a set value when the engine coolant temperature is high, the PCM detects a mal-function and a DTC is stored.
Engine coolant temperature (ECT) sensor 1 is used for air/fuel ratio feedback control, ignition timing control, idle speed control, and other functions. The ECT sensor 1 resistance varies depending on the engine coolant temperature. As the engine coolant cools, the ECT sensor 1 resistance increases, and the powertrain control module (PCM) detects a high signal volt-age. As the engine coolant warms, the ECT sensor 1 resistance decreases, and the PCM detects a low signal voltage. If the ECT sensor 1 output voltage is more than a set value when the engine coolant temperature is low, the PCM detects a mal-function and a DTC is stored.
Throttle position (TP) sensor A is a semiconductor type, and it is attached to the throttle body and shaft to determine throttle valve position.
The throttle valve position signal from TP sensor A is transmitted to the powertrain control module (PCM) for target position feedback control.
If the signal from TP sensor A is less than a fixed value for a set time, the PCM detects a TP sensor A malfunction and stores a DTC.
Throttle position (TP) sensor A is a semiconductor type, and it is attached to the throttle body and shaft to determine throttle valve position.
The throttle valve position signal from TP sensor A is transmitted to the powertrain control module (PCM) for target position feedback control.
If the signal from TP sensor A is more than a fixed value for a set time, the PCM detects a TP sensor A malfunction and stores a DTC.
The powertrain control module (PCM) supplies voltage to the engine coolant temperature (ECT) signal circuit (about 5 V) through a pull-up resistor. As the engine coolant cools, the ECT sensor 1 resistance increases, and the PCM detects a high signal voltage. As the engine coolant warms, the ECT sensor 1 resistance decreases, and the PCM detects a low signal voltage.
If the ECT sensor 1 output voltage does not reach a specified temperature at which closed-loop control for stoichiometric air/ fuel ratio starts within a set time, depending on the initial coolant temperature after starting the engine, the PCM detects a malfunction and a DTC is stored.
The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) has a linear signal output in relation to the oxygen concentration. The powertrain control module (PCM) computes the air/fuel ratio from rear A/F sensor output voltage and uses the fuel feedback control to improve exhaust emissions. The PCM measures the response characteristics against the rear A/F sensor output, and if the average inversion cycle time is less than the specified value, it detects a deteriorated response and stores a DTC.
The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold, and it detects oxygen content in the exhaust gas. The rear A/F sensor outputs voltage to the powertrain control module (PCM). The PCM controls fuel injection time by comparing the target air/fuel ratio with the rear A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. The heater is controlled by the PCM and is energized when the sensor element temperature is low. It heats the sensor to stabilize the detection of oxygen content. The PCM monitors the rear A/F sensor heater output (return check). A malfunction is detected if the return signals do not meet the command value (for heater activation) in the PCM for a set time period or more and a DTC is stored.
A heater for the zirconia element is embedded in the rear secondary heated oxygen sensor (secondary HO2S (bank 1, sensor 2)), and it is controlled by the powertrain control module (PCM). When activated, it heats the sensor to stabilize and speed up the detection of oxygen content when the exhaust gas temperature is cold.
If the rear secondary HO2S heater draws more or less than a specified amperage, the PCM detects a malfunction and a DTC is stored.
The front air/fuel ratio (A/F) sensor (bank 2, sensor 1) has a linear signal output in relation to the oxygen concentration. The powertrain control module (PCM) computes the air/fuel ratio from the front A/F sensor output voltage and uses the fuel feedback control to improve exhaust emissions. The PCM measures the response characteristics against the front A/F sensor output, and if the accumulated value within the specified time is less than the specified value, it detects a deteriorated response and stores a DTC.
The front air/fuel ratio (A/F) sensor (bank 2, sensor 1) is installed in the exhaust manifold, and it detects oxygen content in the exhaust gas. The front A/F sensor outputs voltage to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the front A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. The heater is controlled by the PCM and is energized when the sensor element temperature is low. It heats the sensor to stabilize the detection of oxygen content. The PCM monitors the front A/F sensor heater output (return check). A malfunction is detected if the return signals do not meet the command value (for heater activation) in the PCM for a set time period or more and a DTC is stored.
A heater for the zirconia element is embedded in the front secondary heated oxygen sensor (secondary HO2S (bank 2, sensor 2)) and is controlled by the powertrain control module (PCM). When activated, it heats the sensor to stabilize and speed up the detection of oxygen content when the exhaust gas temperature is cold.
If the front secondary HO2S heater draws more or less than a specified amperage, the PCM detects a malfunction and stores a DTC.
Throttle position (TP) sensor B is a semiconductor type, and it is attached to the throttle body and shaft to determine throttle valve position. The throttle valve position signal from TP sensor B is transmitted to the powertrain control module (PCM) for target position feedback control. If the signal from TP sensor B is less than a fixed value for a set time, the PCM detects a TP sensor B malfunction and stores a DTC.
Throttle position (TP) sensor B is a semiconductor type, and it is attached to the throttle body and shaft to determine throttle valve position. The throttle valve position signal from TP sensor B is transmitted to the powertrain control module (PCM) for target position feedback control. If the signal from TP sensor B is more than a fixed value for a set time, the PCM detects a TP sensor B malfunction and stores a DTC.
The crankshaft vibrates slightly when each cylinder fires. If a misfire occurs, the crankshaft rotation speed changes rapidly. The powertrain control module (PCM) monitors the crankshaft rotation speed based on the output pulses from the crankshaft position (CKP) sensor. By monitoring changes in the crankshaft rotation speed, the PCM counts the number of misfires and determines which cylinder is misfiring. If more than one DTC from P0301 through P0306 has been stored while misfires in multiple cylinders are detected, a malfunction is detected and a DTC is stored.
There are two types of misfire detection.
Type 1 (1 drive cycle): When the number of misfires per 200 engine revolutions reaches the level that damages the three way catalyst (TWC), a DTC is stored and the MIL blinks. When the misfire ceases, the MIL remains on steady instead of blinking.
Type 2 (2 drive cycles): When the number of misfires per 1,000 engine revolutions reaches the level that affects exhaust emissions, a DTC is stored and the MIL comes on.
The crankshaft vibrates slightly when each cylinder fires. If a misfire occurs, the crankshaft rotation speed changes rapidly. The powertrain control module (PCM) monitors engine misfiring based on the output pulses from the crankshaft position (CKP) sensor, counts the number of misfires, and determines which cylinder is misfiring. If a misfire is detected, a DTC is stored.
There are two types of misfire detection.
Type 1 (1 drive cycle): When the number of misfires per 200 engine revolutions reaches the level that damages the three way catalyst (TWC), a DTC is stored and the MIL blinks. When the misfire ceases, the MIL remains on steady instead of blinking.
Type 2 (2 drive cycles): When the number of misfires per 1,000 engine revolutions reaches the level that affects exhaust emissions, a DTC is stored and the MIL comes on.
The knock sensor is mounted on the engine block and detects engine knock. The vibrations caused by knocking are converted into electrical signals through the piezo ceramic element. The powertrain control module (PCM) controls the ignition timing based on the electrical signals. If the signals from the knock sensor do not vary for a set time period, the PCM detects a malfunction and stores a DTC.
Crankshaft position (CKP) sensor A consists of a rotor and a semiconductor that detects rotor position. When the engine starts, the rotor turns and the magnetic flux in the semiconductor changes. The changes of magnetic flux are converted into pulsing signals to the powertrain control module (PCM). CKP sensor A detects injection/ignition timing for each cylinder and engine speed.
If no pulsing signals are detected from CKP sensor A, a malfunction is detected and a DTC is stored.
Crankshaft position (CKP) sensor A consists of a rotor and a semiconductor that detects rotor position. When the engine starts, the rotor turns and the magnetic flux in the semiconductor changes. The changes of magnetic flux are converted into pulsing signals to the powertrain control module (PCM). CKP sensor A detects injection/ignition timing for each cylinder and engine speed.
If an abnormal amount of pulsing signals are detected from CKP sensor A, a malfunction is detected and a DTC is stored.
The camshaft position (CMP) sensor detects the intake camshaft timing and sends pulsing signals to the powertrain control module (PCM). The PCM determines the camshaft position according to the signals from the crankshaft position (CKP) sensor and the CMP sensor. If no pulsing signals are detected from the CMP sensor, a malfunction is detected and a DTC is stored.
The camshaft position (CMP) sensor detects the intake camshaft timing and sends pulsing signals to the powertrain control module (PCM). The PCM determines the camshaft position according to the signals from the crankshaft position (CKP) sensor and the CMP sensor. If the number of pulsing signals from the CMP sensor during intervals between the CKP standard pulses is more or less than the proper number, a malfunction is detected and a DTC is stored.
Crankshaft position (CKP) sensor B consists of a rotor and a semiconductor that detects rotor position. When the engine starts, the rotor turns and the magnetic flux in the semiconductor changes. The changes of magnetic flux are converted into pulsing signals to the powertrain control module (PCM). CKP sensor B detects injection/ignition timing for each cylinder and engine speed.
If no pulsing signals are detected from CKP sensor B, a malfunction is detected and a DTC is stored.
Crankshaft position (CKP) sensor B consists of a rotor and a semiconductor that detects rotor position. When the engine starts, the rotor turns and the magnetic flux in the semiconductor changes. The changes of magnetic flux are converted into pulsing signals to the powertrain control module (PCM). CKP sensor B detects injection/ignition timing for each cylinder and engine speed.
If an abnormal amount of pulsing signals are detected from CKP sensor B, a malfunction is detected and a DTC is stored.
The exhaust gas recirculation (EGR) valve is controlled by the powertrain control module (PCM). When the valve is opened, the exhaust gas flows from the exhaust manifold to the intake manifold through the EGR system. It is mixed with the air/fuel mixture to be drawn into the combustion chamber to lower peak combustion temperature to reduce NOx. The EGR flow is inspected as follows. The EGR valve is closed during deceleration with the throttle valve fully closed. Then the PCM fully opens the EGR valve. After a set time, the PCM computes the ratio of the present EGR flow to the normal EGR flow by monitoring the fluctuation of the intake manifold pressure between when the EGR valve is fully opened and when it is fully closed. If the EGR flow rate is lower than normal, a malfunction is detected and a DTC is stored.
The exhaust gas recirculation (EGR) valve, which is controlled by the powertrain control module (PCM), is opened and the exhaust gas flows from the exhaust manifold through the EGR valve and the intake manifold and the EGR passage. The exhaust gas is circulated into the air/fuel mixture and the mixture is drawn into the combustion chamber to lower combustion temperatures, thus reducing oxides of nitrogen (NOx) emissions.
A sensor (lift sensor) is built into the EGR valve and detects the amount of valve lift. The command value for the target valve lift is stored in the PCM so that exhaust gas recirculation can be optimized according to driving conditions.
Comparing this command value with the lift sensor output signal value, the PCM controls the EGR valve to make the amount of actual valve lift equal to the command value.
If the lift sensor output (actual valve lift) is greater than the commanded valve lift, an abnormality in the EGR valve or the lift sensor output is determined.
The exhaust gas recirculation (EGR) system reduces oxides of nitrogen (NOx). NOx is generated by high combustion temperatures. The EGR system lowers peak combustion temperature by recirculating exhaust gas into the air/fuel mixture, thus reducing NOx emissions. The amount of exhaust gas recirculated is dependent on the driving conditions; a command value (the amount of valve lift) is stored in the powertrain control module (PCM) for each condition. The EGR valve position sensor indicates the amount of valve lift, and the PCM controls the EGR valve so that the amount of actual valve lift equals the command value.
If the EGR valve position sensor output signal voltage is not within a specified value, a malfunction is detected and a DTC is stored.
The three way catalytic converter (TWC) converts hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) in the exhaust gas to water vapor, carbon dioxide (CO2), and dinitrogen (N2).
The TWC efficiency does not depend entirely on engine conditions or the deterioration level of the TWC. It can be optimized by stabilizing the secondary HO2S output.
If the TWC deteriorates, the air/fuel ratio downstream of the TWC (the secondary HO2S output) often differs from the target secondary HO2S output, and the status is represented by the parameter (SIGSQRLS).
Therefore, if the SIGSQRLS exceeds a specified value for a set time, a malfunction is detected and a DTC is stored.
The three way catalytic converter (TWC) converts hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) in the exhaust gas to water vapor, carbon dioxide (CO2), and dinitrogen (N2).
The TWC efficiency does not depend entirely on engine conditions or the deterioration level of the TWC. It can be optimized by stabilizing the secondary HO2S output.
If the TWC deteriorates, the air/fuel ratio downstream of the TWC (the secondary HO2S output) often differs from the target secondary HO2S output, and the status is represented by the parameter (SIGSQRLS).
Therefore, if the SIGSQRLS exceeds a specified value for a set time, a malfunction is detected and a DTC is stored.
The evaporative emission (EVAP) canister purge valve is attached to the vacuum port between the EVAP canister and the intake manifold. The powertrain control module (PCM) does not turn on the EVAP canister purge valve when the engine coolant temperature is 140 °F (60 °C) or less. The PCM adjusts the amount of fuel vapor sent to the engine by controlling the EVAP canister purge valve duty cycle.
When the return signal does not change according to the EVAP canister purge valve duty cycle for a set time, the PCM detects a malfunction, and a DTC is stored.
The fuel tank pressure (FTP) sensor is installed on the evaporative emission (EVAP) canister. The FTP sensor is used to detect leaks in the EVAP system. The powertrain control module (PCM) monitors the FTP sensor output voltage. The FTP sensor output voltage rises as the fuel tank pressure increases. Conversely, the FTP sensor output voltage drops as the fuel tank pressure decreases. Rapid changes in the FTP sensor output voltage due to electrical noise or an intermittent open during the EVAP leak detection may cause incorrect leak detection, so abnormal output is monitored.
If the FTP sensor output voltage changes a specified number of times within a set time, the PCM detects a malfunction and stores a DTC.
The fuel tank pressure (FTP) sensor is installed on the evaporative emission (EVAP) canister and detects the fuel tank pressure. The FTP sensor is used to detect leaks in the EVAP system.
The powertrain control module (PCM) monitors the FTP sensor output voltage. The FTP sensor output voltage rises as the fuel tank pressure increases. Conversely, the FTP sensor output voltage drops as the fuel tank pressure decreases. If the FTP sensor output voltage does not reach a target value within a set time after starting the engine in a cold condition, the PCM detects a malfunction and stores a DTC.
The fuel tank pressure (FTP) sensor is installed on the evaporative emission (EVAP) canister and detects the fuel tank pressure. The FTP sensor is used to detect leaks in the EVAP system.
The powertrain control module (PCM) monitors the FTP sensor output voltage. The FTP sensor output voltage rises as the fuel tank pressure increases. Conversely, the FTP sensor output voltage drops as the fuel tank pressure decreases. If the FTP sensor output voltage is higher than a target value within a set time after starting the engine in a cold condition, the PCM detects a malfunction and stores a DTC.
There are two conditions when the evaporative emission (EVAP) system will not hold vacuum sufficiently, and the pressure in the fuel tank doesn't become negative.
- EVAP system low purge flow.
- EVAP system leakage or the fuel fill cap loose/off.
Here is a description of condition 2
The powertrain control module (PCM) monitors the fuel tank pressure (FTP) sensor output. If the FTP sensor output does not indicate the specified vacuum when leak checking and the fuel vapor density is high, the PCM detects a large leak (fuel fill cap loose/off) and a DTC is stored. [The malfunction detection is performed during EVAP system leak detection (P0442, P0455, P0456).]
The fuel level sensor is incorporated with the fuel pump and installed in the fuel tank. Using a built-in potentiometer and float, it converts the movement of the float into electrical signals that correspond to the fuel level, and it measures the remaining fuel in the fuel tank. If the powertrain control module (PCM) receives no change in the fuel level sensor output after driving for a specified number of miles, it detects a malfunction and stores a DTC.
The fuel level sensor is incorporated into the fuel pump and installed in the fuel tank. Using a built-in potentiometer and float, it converts the movement of the float to electrical signals as an output that corresponds to fuel level variations in the fuel tank. The fuel level, which is indicated by the gauge assembly, is sent to the powertrain control module (PCM) via the controller area network (CAN). If the PCM detects a signal from the fuel level sensor below a predetermined value for a set time or more, it detects a malfunction and stores a DTC.
The fuel level sensor is incorporated into the fuel pump and installed in the fuel tank. Using a built-in potentiometer and float, it converts the movement of the float to electrical signals that correspond to fuel level variations, and it measures the remaining fuel in the fuel tank. The fuel level, which is read by the gauge assembly, is sent to the powertrain control module (PCM) via the controller area network (CAN). If the PCM detects a signal voltage from the fuel level sensor above a predetermined value for a set time or more, it detects a malfunction and stores a DTC.
The powertrain control module (PCM) adjusts the amount of fuel vapor sent to the engine by controlling the evaporative emission (EVAP) canister purge valve. If the EVAP canister purge valve is stuck open, engine vacuum flows into the purge line before purge control starts after starting the engine. The PCM monitors the fuel tank pressure (FTP) sensor output when purge control starts. If the FTP sensor output indicates negative pressure, the PCM detects a malfunction in the EVAP canister purge valve, and a DTC is stored.
There are two conditions when the evaporative emission (EVAP) system will not hold vacuum sufficiently, and the pressure in the fuel tank doesn't become negative.
- EVAP system low purge flow.
- EVAP system leakage or the fuel fill cap loose/off.
Here is a description of condition 1
The malfunction detection is performed during EVAP system leak detection (P0442, P0455, P0456).
The powertrain control module (PCM) monitors the fuel tank pressure (FTP) sensor output. If the FTP sensor output does not indicate the prescribed negative pressure when purging, the PCM detects a malfunction and a DTC is stored.
The evaporative emission (EVAP) canister vent shut valve is attached to the EVAP canister to control the venting of the EVAP canister to atmosphere.
The EVAP canister vent shut valve is open (open to atmosphere) when the VSV signal is OFF.
If the return signal is "OFF" when the powertrain control module (PCM) outputs the "ON" signal to the EVAP canister vent shut valve, the PCM detects a malfunction and a DTC is stored.
The evaporative emission (EVAP) canister vent shut valve is attached to the EVAP canister to control the venting of the EVAP canister to atmosphere.
The EVAP canister vent shut valve is open (open to atmosphere) when the VSV signal is OFF.
If the return signal is "ON" when the powertrain control module (PCM) outputs the "OFF" signal to the EVAP canister vent shut valve, the PCM detects a malfunction and a DTC is stored.
A target idle speed that meets the engine operating conditions (coolant temperature, A/C ON or OFF, etc.) is stored in the powertrain control module (PCM). The PCM monitors and controls the idle speed so that the actual idle speed is equal to the target idle speed. If the actual idle speed varies beyond a specified value from the target speed over a certain period of time, the PCM detects a malfunction in the idle speed control system and a DTC is stored.
A target idle speed that meets the engine operating conditions (coolant temperature, A/C ON or OFF, etc.) is stored in the powertrain control module (PCM). The PCM monitors and controls the idle speed so that the actual idle speed is equal to the target idle speed. If the actual idle speed varies beyond a specified value from the target speed over a certain period of time, the PCM detects a malfunction in the idle speed control system and a DTC is stored.
The alternator is driven by the engine and generates electricity to supply the necessary power to the electrical system and to charge the battery. The alternator voltage target values of 14.5 V and 12.5 V are achieved by switching the alternator control mode (controlled by the powertrain control module (PCM)). The alternator output signal is sent to the PCM, and it varies according to the battery's state of charge, the electrical load, and engine rpm.
When the IGP (power source) terminal voltage is a set value or less and this condition continues for a set time, the PCM detects a malfunction and a DTC is stored.
If there is a short to ground in the harness between the powertrain control module (PCM) and the PGM-FI main relay 1, the PGM-FI main relay 1 stays ON even though the ignition switch is OFF, and the PCM remains active. However, the engine is not running because the power for the gauges, the ignition, and the fuel pump is turned OFF by the ignition switch. When the PCM operates for a set time after the ignition switch is turned OFF, a malfunction is detected and a DTC is stored.
The powertrain control module (PCM) is equipped with an update program to update its control program. The programs in the CPU of the PCM are classified as a PCM program (update-capable program) and a program for the update function (non-updateable program). The program update only updates the PCM program.
When the PCM power is turned off during an update, the power for the update function is lost, and the update process stops.
When the program update is stopped before it is completed, the PCM stores a DTC that indicates the update is not finished.
The powertrain control module (PCM) is equipped with a keep-alive memory. The data (control learn data etc) for powertrain control and information (vehicle identification number (VIN), etc) related to vehicle control is stored in the keep alive memory, so that it can be maintained even when power is not supplied to the PCM such as when the battery is disconnected. When power is restored to the PCM, the CPU retrieves the stored information from the keep-alive memory, but when the data retrieval process is not finished normally, a malfunction is detected and a DTC is stored.
The CPU writes data to the keep-alive memory from the CPU: Control related data is written when the ignition is turned on, and vehicle information when commanded from the HDS.
If the data writing process is not completed normally, a malfunction is detected and a DTC is stored.
The main CPU uses serial communication lines to communicate with the sub CPU.
When the serial communication signal from the sub CPU is not input or when the communication signal is abnormal for a set time, the main CPU detects a malfunction and a DTC is stored.
The electronic throttle control system (ETCS) opens and closes the throttle valve electronically. This system consists of the throttle actuator, the throttle valve, throttle position (TP) sensors A/B, accelerator pedal position (APP) sensors A/B, and the powertrain control module (PCM).
When the driver operates the acceleration pedal, the accelerator pedal position (APP) sensor indicates the actual pedal position. The acceleration pedal stepping amount is converted to a signal at the APP sensor, and the throttle valve opening degree target value is based on this amount. The throttle actuator is driven to be this target value, and the APP value must agree. The actual throttle valve opening is detected by TP sensor A, attached to the throttle body. The throttle actuator controller makes a self-diagnosis of the ROM, RAM, and A/D converter, and when the internal data is abnormal, a malfunction is detected in the throttle actuator controller and a DTC is stored.
The powertrain control module (PCM) stores a vehicle identification number (VIN) in the keep-alive memory and outputs the VIN according to the command from the scan tool.
The VIN for each vehicle is registered to the PCM using the scan tool. The registered VIN is read by the CPU from the keep-alive memory after the ignition is turned on or after the Clear command is executed.
If the VIN is not registered in the keep-alive memory when the ignition is turned on or when the Clear command is executed, it is detected as a VIN unregistered condition and a DTC is stored.
The powertrain control module (PCM) is equipped with a power supply to supply 5 V to each sensor, and it supplies stable power to each sensor as a sensor reference voltage.
The voltage value to the sensor is loaded in the CPU of the PCM (A/D input), and when the sensor voltage is above or below the specified voltage range for a set time, a malfunction is detected and a DTC is stored.
After the ignition switch is turned off, the powertrain control module (PCM) does not shut down immediately. After finishing a predetermined process according to the request of each device and system, the power supply is automatically disconnected (self shut-down function). The PCM power is disconnected by controlling PGM-FI main relay 1 (FI MAIN).
During a normal PCM shut down, the shut down process is executed by the CPU, PGM-FI main relay 1 (FI MAIN) is turned off, and the voltage to the PCM is turned off to shut down the PCM. When the voltage to the PCM is turned off and the PCM shuts down without the normal shut down procedure, a malfunction in the PGM-FI main relay 1 (FI MAIN) control circuit is detected and a DTC is stored.
The transmission range switch is attached to the control shaft. Operating the shift lever makes the control shaft rotate via the shift cable. The A/T gear position indicator indicates which position is selected according to the Low/High signal combinations which vary based on shift lever position. The control shaft changes the position of the transmission range switch, activates the manual valve, and switches hydraulic pressure to shift the transmission through forward/neutral/reverse. The transmission range switch signal is used to determine the shift schedule. The voltage is 12 V (High) at the powertrain control module (PCM) input terminal when each transmission range switch position is open, and it is 0 V (Low) when each switch is closed. If the PCM detects multiple switch inputs instead of the correct switch input for the selected range at that time, it detects a malfunction and stores a DTC.
The transmission range switch is attached to the control shaft. Operating the shift lever makes the control shaft rotate via the shift cable. The A/T gear position indicator indicates which position is selected according to the Low/High signal combinations which vary based on the control shaft rotational angle. The control shaft changes the position of the transmission range switch, activates the manual valve, and switches hydraulic pressure to shift the transmission through forward/neutral/reverse. The transmission range switch signal is used to determine the shift schedule. The voltage is 12 V (High) at the powertrain control module (PCM) input terminal when each transmission range switch position is open, and it is 0 V (Low) when each switch is closed. If the FWD switch stays open while the vehicle repeatedly accelerates to a specified vehicle speed and then stops despite being in the D position, the PCM detects a malfunction in the transmission range switch (open) and stores a DTC.
The ATF temperature sensor is a thermistor type sensor whose resistance changes according to the change in ATF temperature. The powertrain control module (PCM) sends a 5 V reference voltage to the grounded sensor through a pull-up resistor. When the ATF temperature is low, the sensor resistance increases and the PCM detects a high signal voltage. As the ATF temperature rises, the sensor resistance decreases and the PCM detects a low signal voltage.
If the ATF temperature sensor signal doesn't change, the PCM detects a malfunction and a DTC is stored.
The ATF temperature sensor is a thermistor type sensor whose resistance changes according to the change in ATF temperature. The powertrain control module (PCM) sends a 5 V reference voltage to the grounded sensor through a pull-up resistor. When the ATF temperature is low, the sensor resistance increases and the PCM detects a high signal voltage. As the ATF temperature rises, the sensor resistance decreases and the PCM detects a low signal voltage.
When the ATF temperature sensor signal voltage to the PCM is under the specification, indicating that the temperature is above the specification (a short to ground), a malfunction is detected and a DTC is stored.
The ATF temperature sensor is a thermistor type sensor whose resistance changes according to the change in ATF temperature. The powertrain control module (PCM) sends a 5 V reference voltage to the grounded sensor through a pull-up resistor. When the ATF temperature is low, the sensor resistance increases and the PCM detects a high signal voltage. As the ATF temperature rises, the sensor resistance decreases and the PCM detects a low signal voltage.
When the ATF temperature sensor signal voltage to the PCM is above the specification, indicating that the temperature is under the specification (open), a malfunction is detected and a DTC is stored.
The input shaft (mainshaft) speed sensor is attached to the outside of the transmission housing. The input shaft (mainshaft) speed sensor generates a pulsing signal according to the speed of the input shaft (mainshaft) idler gear on the input shaft (mainshaft). Using that signal, the powertrain control module (PCM) determines the speed of the input shaft (mainshaft). If no pulses occur with the input shaft (mainshaft) rotating, the PCM detects a malfunction that may be caused by an open, a temporary open, or a short to ground. Based on the velocity ratio measured by the output shaft (countershaft) speed sensor and the input shaft (mainshaft) speed sensor, a malfunction is detected and a DTC is stored.
The input shaft (mainshaft) speed sensor is attached to the outside of the transmission housing. The input shaft (mainshaft) speed sensor generates a pulsing signal according to the speed of the input shaft (mainshaft) idler gear on the input shaft (mainshaft). Using that signal, the powertrain control module (PCM) determines the speed of the input shaft (mainshaft). If no pulses occur with the input shaft (mainshaft) rotating, the PCM detects a malfunction that may be caused by an open, a temporary open, or a short to ground. Based on the correlation between the vehicle speed measured by the output shaft (countershaft) speed sensor and the input shaft (mainshaft) speed sensor, a malfunction is detected and a DTC is stored.
The input shaft (mainshaft) speed sensor is attached to the outside of the transmission housing. The input shaft (mainshaft) speed sensor generates a pulsing signal according to the speed of the input shaft (mainshaft) idler gear on the input shaft (mainshaft). Using that signal, the powertrain control module (PCM) determines the speed of the input shaft (mainshaft). If no pulses occur with the input shaft (mainshaft) rotating, the PCM detects a malfunction that may be caused by an open, a temporary open, or a short to ground. Based on the fluctuation of the vehicle speed measured by the input shaft (mainshaft) speed sensor, a malfunction is detected and a DTC is stored.
The output shaft (countershaft) speed sensor is attached to the outside of the transmission housing. The output shaft (countershaft) speed sensor generates a pulsing signal according to the speed of the park gear on the output shaft (countershaft). Using that signal, the powertrain control module (PCM) determines the speed of the output shaft (countershaft). If pulse dropouts occur with the output shaft (countershaft) rotating, the PCM detects a malfunction that may be caused by an open, a temporary open, or a short to ground. Based on the velocity ratio measured by the input shaft (mainshaft) speed sensor and the output shaft (countershaft) speed sensor, a malfunction is detected and a DTC is stored.
The output shaft (countershaft) speed sensor is attached to the outside of the transmission housing. The output shaft (countershaft) speed sensor generates a pulsing signal according to the speed of the park gear on the output shaft (countershaft). Using that signal, the powertrain control module (PCM) determines the speed of the output shaft (countershaft). If pulse dropouts occur with the output shaft (countershaft) rotating, the PCM detects a malfunction that may be caused by an open, a temporary open, or a short to ground. Based on the correlation between the vehicle speed measured by the output shaft (countershaft) speed sensor and the input shaft (mainshaft) speed sensor, a malfunction is detected and a DTC is stored.
The output shaft (countershaft) speed sensor is attached to the outside of the transmission housing. The output shaft (countershaft) speed sensor generates a pulsing signal according to the speed of the park gear on the output shaft (countershaft). Using that signal, the powertrain control module (PCM) determines the speed of the output shaft (countershaft). If pulse dropouts occur with the output shaft (countershaft) rotating, the PCM detects a malfunction that may be caused by an open, a temporary open, or a short to ground. Based on the fluctuation of the vehicle speed measured by the output shaft (countershaft) speed sensor, a malfunction is detected and a DTC is stored.
To engage 1st gear, line pressure is supplied to the 1st clutch piston, engaging the 1st clutch, and the secondary shaft and the secondary shaft 1st gear are connected and revolve together. Hydraulic pressure is supplied to the 1st clutch through the ATF strainer --> the ATF pump --> the regulator valve --> the manual valve --> the shift valves --> the feed pipe --> 1st clutch piston. (A shift valve failure in the supplying route above is detected by the malfunction detection of each shift solenoid valve.) The powertrain control module (PCM) computes the ratio of the input shaft (mainshaft) speed to the output shaft (countershaft) speed. When the ratio is not the 1st gear ratio, it is detected as a malfunction of the hydraulic circuit or the 1st clutch, and a DTC is stored.
To engage 2nd gear, line pressure is supplied to the 2nd clutch piston, engaging the 2nd clutch, and the secondary shaft and the secondary shaft 2nd gear are connected and revolve together. Hydraulic pressure is supplied to the 2nd clutch through the ATF strainer --> the ATF pump --> the regulator valve --> the manual valve --> the shift valves --> the feed pipe --> 2nd clutch piston. (A shift valve failure in the supplying route above is detected by the malfunction detection of each shift solenoid valve.) The powertrain control module (PCM) computes the ratio of the input shaft (mainshaft) speed to the output shaft (countershaft) speed. When the ratio is not the 2nd gear ratio, it is detected as a malfunction of the hydraulic circuit or the 2nd clutch, and a DTC is stored.
To engage 3rd gear, line pressure is supplied to the 3rd clutch piston, engaging the 3rd clutch, and the output shaft (countershaft) and the output shaft (countershaft) 3rd gear are connected and revolve together. Hydraulic pressure is supplied to the 3rd clutch through the ATF strainer --> the ATF pump --> the regulator valve --> the manual valve --> the shift valves --> the feed pipe --> 3rd clutch piston. (A shift valve failure in the supplying route above is detected by the malfunction detection of each shift solenoid valve.) The powertrain control module (PCM) computes the ratio of the input shaft (mainshaft) speed to the output shaft (countershaft) speed. When the ratio is not the 3rd gear ratio, it is detected as a malfunction of the hydraulic circuit or the 3rd clutch, and a DTC is stored.
To engage 4th gear, line pressure is supplied to the 4th clutch piston, engaging the 4th clutch, and the input shaft (mainshaft) and the input shaft (mainshaft) 4th gear are connected and revolve together. Hydraulic pressure is supplied to the 4th clutch through the ATF strainer --> the ATF pump --> the regulator valve --> the manual valve --> the shift valves --> the feed pipe --> 4th clutch piston. (A shift valve failure in the supplying route above is detected by the malfunction detection of each shift solenoid valve.) The powertrain control module (PCM) computes the ratio of the input shaft (mainshaft) speed to the output shaft (countershaft) speed. When the ratio is not the 4th gear ratio, it is detected as a malfunction of the hydraulic circuit or the 4th clutch, and a DTC is stored.
To engage 5th gear, line pressure is supplied to the 5th clutch piston, engaging the 5th clutch, and the input shaft (mainshaft) and the input shaft (mainshaft) 5th gear are connected and revolve together. Hydraulic pressure is supplied to the 5th clutch through the ATF strainer --> the ATF pump --> the regulator valve --> the manual valve --> the shift valves --> the feed pipe --> 5th clutch piston. (A shift valve failure in the supplying route above is detected by the malfunction detection of each shift solenoid valve.) The powertrain control module (PCM) computes the ratio of the input shaft (mainshaft) speed to the output shaft (countershaft) speed. When the ratio is not the 5th gear ratio, it is detected as a malfunction of the hydraulic circuit or the 5th clutch, and a DTC is stored.
The power transfer capacity of the torque converter clutch is controlled by the balance of automatic transmission fluid (ATF) supply to and discharge from the torque converter. When hydraulic pressure is applied internally, the torque converter clutch turns ON, and when hydraulic pressure is applied from the back pressure side, the torque converter clutch turns OFF. As the hydraulic pressure from the internal pressure side increases, the power transfer capacity of the torque converter clutch increases. The direction of hydraulic pressure supply is switched by the torque converter clutch solenoid valve and the lockup shift valve. ATF is supplied from the internal pressure side to the torque converter clutch solenoid valve when the signal from the powertrain control module (PCM) is ON (12 V), and ATF is supplied from the back pressure side when it is OFF (0 V). The balance of internal pressure and back pressure is controlled by A/T clutch pressure control solenoid valve C, the lock-up control valve, and the lock-up timing valve. A/T clutch pressure control solenoid valve C maximizes the power transfer capacity of the torque converter clutch when the signal from the PCM is ON (1 A), and it minimizes the power transfer capacity of the torque converter clutch when the signal from the PCM is OFF (0 A). If the ratio of engine speed and input shaft (mainshaft) speed is not about 1:1 while the PCM is issuing the command to turn the torque converter clutch solenoid valve and A/T clutch pressure control solenoid valve C ON, the PCM detects a faulty lock-up control system and stores a DTC.
A/T clutch pressure control solenoid valve A is installed in the transmission housing. A/T clutch pressure control solenoid valve A is operated by the powertrain control module (PCM) and converts the modulated pressure to A/T clutch pressure control solenoid A pressure, which operates CPC valve A. Line pressure is modulated to clutch pressure control A pressure (CPC A pressure) by CPC valve A and the CPC valve A spring. A signal from the PCM is output to the proper gear clutch, determined by the gear schedule, to supply the proper CPC pressure according to the driving conditions. When the current from the PCM is high (ON), A/T clutch pressure control solenoid valve A operates and the CPC valve A pressure increases. When the current from the PCM is low (OFF), A/T clutch pressure control solenoid valve A turns off and CPC valve A pressure decreases. The PCM monitors the input shaft (mainshaft) speed and the output shaft (countershaft) speed at the gear change determined by the shift schedule. When an improper gear ratio is output compared to the predetermined gear ratio, an A/T clutch pressure control solenoid valve A OFF failure is detected and a DTC is stored.
A/T clutch pressure control solenoid valve A is installed in the transmission housing. A/T clutch pressure control solenoid valve A is operated by the powertrain control module (PCM) and converts the modulated pressure to A/T clutch pressure control solenoid A pressure, which operates CPC valve A. Line pressure is modulated to clutch pressure control A pressure (CPC A pressure) by CPC valve A and the CPC valve A spring. A signal from the PCM is output to the proper gear clutch, determined by the gear schedule, to supply the proper CPC pressure according to the driving conditions. When the current from the PCM is high (ON), A/T clutch pressure control solenoid valve A operates and the CPC valve A pressure increases. When the current from the PCM is low (OFF), A/T clutch pressure control solenoid valve A turns off and CPC valve A pressure decreases. The PCM monitors the input shaft (mainshaft) speed and the output shaft (countershaft) speed at the gear change determined by the shift schedule. When an improper gear ratio is output compared to the predetermined gear ratio, an A/T clutch pressure control solenoid valve A ON failure is detected and a DTC is stored.
Shift solenoid valve A is installed in the transmission housing. It is controlled by the ON/OFF signal from the powertrain control module (PCM), to apply modulated pressure to shift valve A. The signal from the PCM is output to apply clutch pressure control pressure to the proper gear change clutch according to the gear change schedule. When the signal to shift solenoid valve A from the PCM is ON, and modulated pressure is discharged, shift valve A is inactive. When the signal to shift solenoid valve A from the PCM is OFF, and modulated pressure is applied to shift valve A, it operates against the shift valve A spring. The PCM monitors the input shaft (mainshaft) speed and the output shaft (countershaft) speed at the gear change determined by the shift schedule. When an improper gear ratio is output compared to the predetermined gear change mode, a shift solenoid valve A OFF failure is detected and a DTC is stored.
Shift solenoid valve A is installed in the transmission housing. It is controlled by the ON/OFF signal from the powertrain control module (PCM), to apply modulated pressure to shift valve A. The signal from the PCM is output to apply clutch pressure control pressure to the proper gear change clutch according to the gear change schedule. When the signal to shift solenoid valve A from the PCM is ON, and modulated pressure is discharged, shift valve A is inactive. When the signal to shift solenoid valve A from the PCM is OFF, and modulated pressure is applied to shift valve A, it operates against the shift valve A spring. The PCM monitors the input shaft (mainshaft) speed and the output shaft (countershaft) speed at the gear change determined by the shift schedule. When an improper gear ratio is output compared to the predetermined gear change mode, a shift solenoid valve A ON failure is detected and a DTC is stored.
Shift solenoid valve B is installed in the transmission housing. It is controlled by the ON/OFF signal from the powertrain control module (PCM), to apply modulated pressure to shift valve B. The signal from the PCM is output to apply clutch pressure control pressure to the proper gear change clutch according to the gear change schedule. When the signal to shift solenoid valve B from the PCM is ON, and modulated pressure is discharged, shift valve B is inactive. When the signal to shift solenoid valve B from the PCM is OFF, and modulated pressure is applied to shift valve B, it operates against the shift valve B spring. The PCM monitors the input shaft (mainshaft) speed and the output shaft (countershaft) speed at the gear change determined by the shift schedule. When an improper gear ratio is output compared to the predetermined gear change mode, a shift solenoid valve B OFF failure is detected and a DTC is stored.
Shift solenoid valve B is installed in the transmission housing. It is controlled by the ON/OFF signal from the powertrain control module (PCM), to apply modulated pressure to shift valve B. The signal from the PCM is output to apply clutch pressure control pressure to the proper gear change clutch according to the gear change schedule. When the signal to shift solenoid valve B from the PCM is ON, and modulated pressure is discharged, shift valve B is inactive. When the signal to shift solenoid valve B from the PCM is OFF, and modulated pressure is applied to shift valve B, it operates against the shift valve B spring. The PCM monitors the input shaft (mainshaft) speed and the output shaft (countershaft) speed at the gear change determined by the shift schedule. When an improper gear ratio is output compared to the predetermined gear change mode, a shift solenoid valve B ON failure is detected and a DTC is stored.
Shift solenoid valve C is installed in the transmission housing. It is controlled by the ON/OFF signal from the powertrain control module (PCM), to apply modulated pressure to shift valve C. The signal from the PCM is output to apply clutch pressure control pressure to the proper gear change clutch according to the gear change schedule. When the signal to shift solenoid valve C from the PCM is ON, and modulated pressure is discharged, shift valve C is inactive. When the signal to shift solenoid valve C from the PCM is OFF, and modulated pressure is applied to shift valve C, it operates against the shift valve C spring. The PCM monitors the input shaft (mainshaft) speed and the output shaft (countershaft) speed at the gear change determined by the shift schedule. When an improper gear ratio is output compared to the predetermined gear change mode, a shift solenoid valve C OFF failure is detected and a DTC is stored.
Shift solenoid valve C is installed in the transmission housing. It is controlled by the ON/OFF signal from the powertrain control module (PCM), to apply modulated pressure to shift valve C. The signal from the PCM is output to apply clutch pressure control pressure to the proper gear change clutch according to the gear change schedule. When the signal to shift solenoid valve C from the PCM is ON, and modulated pressure is discharged, shift valve C is inactive. When the signal to shift solenoid valve C from the PCM is OFF, and modulated pressure is applied to shift valve C, it operates against the shift valve C spring. The PCM monitors the input shaft (mainshaft) speed and the output shaft (countershaft) speed at the gear change determined by the shift schedule. When an improper gear ratio is output compared to the predetermined gear change mode, a shift solenoid valve C ON failure is detected and a DTC is stored.
A/T clutch pressure control solenoid valve B is installed in the transmission housing. A/T clutch pressure control solenoid valve B is operated by the powertrain control module (PCM) and converts modulated pressure to A/T clutch pressure control solenoid B pressure, which operates CPC valve B. Line pressure is modulated to clutch pressure control B pressure (CPC B pressure) by CPC valve B and the CPC valve B spring. A signal from the PCM is output to the proper gear clutch, determined by the gear schedule, to supply the proper CPC pressure according to the driving conditions. When the current from the PCM is low (OFF), A/T clutch pressure control solenoid valve B operates and the CPC valve B pressure increases. When the current from the PCM is high (ON), A/T clutch pressure control solenoid valve B turns off and the CPC valve B pressure decreases. The PCM monitors the input shaft (mainshaft) speed and the output shaft (countershaft) speed at the gear change determined by the shift schedule. When an improper gear ratio is output compared to the predetermined gear change mode, an A/T clutch pressure control solenoid valve B OFF failure is detected and a DTC is stored.
A/T clutch pressure control solenoid valve B is installed in the transmission housing. A/T clutch pressure control solenoid valve B is operated by the powertrain control module (PCM) and converts modulated pressure to A/T clutch pressure control solenoid B pressure, which operates CPC valve B. Line pressure is modulated to clutch pressure control B pressure (CPC B pressure) by CPC valve B and the CPC valve B spring. A signal from the PCM is output to the proper gear clutch, determined by the gear schedule, to supply the proper CPC pressure according to the driving conditions. When the current from the PCM is low (OFF), A/T clutch pressure control solenoid valve B operates and the CPC valve B pressure increases. When the current from the PCM is high (ON), A/T clutch pressure control solenoid valve B turns off and the CPC valve B pressure decreases. The PCM monitors the input shaft (mainshaft) speed and the output shaft (countershaft) speed at the gear change determined by the shift schedule. When an improper gear ratio is output compared to the predetermined gear change mode, an A/T clutch pressure control solenoid valve B ON failure is detected and a DTC is stored.
Shift valve D is installed in the control circuit in the transmission. When the shift lever is in D range, shift valve D supplies clutch pressure control A pressure (CPC A pressure) to the 4th clutch and 5th clutch. When the shift lever is in 1st range, shift valve D supplies clutch pressure control B pressure (CPC B pressure) to the 1st/1st-hold clutch. Shift valve D supplies CPC A pressure to the 4th clutch and 5th clutch by increasing the line pressure and CPC A pressure. Shift valve D supplies clutch pressure control B pressure (CPC B pressure) to the 1st/1st-hold clutch which is regulated by the shift valve D spring which decreases the line pressure and CPC A pressure. The powertrain control module (PCM) monitors the input shaft (mainshaft) speed and output shaft (countershaft) speed at the gear change determined by the shift schedule. When an improper ratio is output with the predetermined gear change mode, shift valve D is stuck closed and a DTC is stored.
The 3rd clutch transmission fluid pressure switch is installed in the hydraulic pressure circuit to the 3rd clutch. When hydraulic pressure is supplied to the 3rd clutch, the switch is turned ON. When hydraulic pressure is not supplied to the 3rd clutch, the switch is turned OFF. The signal from the 3rd clutch transmission fluid pressure switch is input to the powertrain control module (PCM). The PCM detects the hydraulic pressure supply conditions at the gear change to 3rd gear (2nd --> 3rd, 4th --> 3rd) to reduce the shock that occurs at the gear change.
If the 3rd clutch transmission fluid pressure switch is ON while driving, and the speed ratio of the output shaft (countershaft) to the input shaft (mainshaft) is other than the 3rd ratio (the ratio is Neutral or 4th), the PCM detects a 3rd clutch transmission fluid pressure switch failure, and a DTC is stored.
The 3rd clutch transmission fluid pressure switch is installed in the hydraulic pressure circuit to the 3rd clutch. When hydraulic pressure is supplied to the 3rd clutch, the switch is turned ON. When hydraulic pressure is not supplied to the 3rd clutch, the switch is turned OFF. The signal from the 3rd clutch transmission fluid pressure switch is input to the powertrain control module (PCM). The PCM detects the hydraulic pressure supply conditions at the gear change to 3rd gear (2nd --> 3rd, 4th --> 3rd) to reduce the shock that occurs at the gear change. If the 3rd clutch transmission fluid pressure switch is OFF while the rotation speed ratio of the input/output pulses is that of 3rd gear, the PCM detects a malfunction in the 3rd clutch transmission fluid pressure switch and stores a DTC.
The 4th clutch transmission fluid pressure switch is installed in the hydraulic pressure circuit to the 4th clutch. When hydraulic pressure is supplied to the 4th clutch, the switch is turned ON. When hydraulic pressure is not supplied to the 4th clutch, the switch is turned OFF. The signal from the 4th clutch transmission fluid pressure switch is input to the powertrain control module (PCM). The PCM detects the hydraulic pressure supply conditions at the gear change to 4th gear (3rd --> 4th, 5th --> 4th) to reduce the shock that occurs at the gear change.
If the 4th clutch transmission fluid pressure switch is ON while driving, and the speed ratio of the output shaft (countershaft) to input shaft (mainshaft) is other than 4th gear (the ratio is Neutral or 5th), the PCM detects a 4th clutch transmission fluid pressure switch failure, and a DTC is stored.
The 4th clutch transmission fluid pressure switch is installed in the hydraulic pressure circuit to the 4th clutch. When hydraulic pressure is supplied to the 4th clutch, the switch is turned ON. When hydraulic pressure is not supplied to the 4th clutch, the switch is turned OFF. The signal from the 4th clutch transmission fluid pressure switch is input to the powertrain control module (PCM). The PCM detects the hydraulic pressure supply conditions at the gear change to 4th gear (3rd --> 4th, 5th --> 4th) to reduce the shock that occurs at the gear change. If the 4th clutch transmission fluid pressure switch is OFF while driving with the rotation speed ratio of the input/output pulses in 4th gear, the PCM detects a 4th clutch transmission fluid pressure switch failure and stores a DTC.
A/T clutch pressure control solenoid valve A is used for clutch pressure control. A spool in A/T clutch pressure control solenoid valve A pushes a valve according to the duty cycle that is controlled by the powertrain control module (PCM) so the hydraulic pressure is proportional to the current. The PCM measures the current flowing through A/T clutch pressure control solenoid valve A and uses feedback control to compensate for the difference between the actual current and the commanded one. If the measured current for the PCM output duty cycle is not within a specified range (open or short), a malfunction is detected and a DTC is stored.
A/T clutch pressure control solenoid valve A is used for clutch pressure control. A spool in A/T clutch pressure control solenoid valve A pushes a valve according to the duty cycle that is controlled by the powertrain control module (PCM) so the hydraulic pressure is proportional to the current. The PCM measures the current flowing through A/T clutch pressure control solenoid valve A and uses feedback control to compensate for the difference between the actual current and the commanded one. If the measured current for the PCM output duty cycle is not within a specified range (open or short), a malfunction is detected and a DTC is stored.
A/T clutch pressure control solenoid valve B is used for clutch pressure control. A spool in A/T clutch pressure control solenoid valve B pushes a valve according to the duty cycle that is controlled by the powertrain control module (PCM) so the hydraulic pressure is proportional to the current. The PCM measures the current flowing through A/T clutch pressure control solenoid valve B and uses feedback control to compensate for the difference between the actual current and the commanded one. If the measured current for the PCM output duty cycle is not within a specified range (open or short), a malfunction is detected and a DTC is stored.
A/T clutch pressure control solenoid valve B is used for clutch pressure control. A spool in A/T clutch pressure control solenoid valve B pushes a valve according to the duty cycle that is controlled by the powertrain control module (PCM) so the hydraulic pressure is proportional to the current. The PCM measures the current flowing through A/T clutch pressure control solenoid valve B and uses feedback control to compensate for the difference between the actual current and the commanded one. If the measured current for the PCM output duty cycle is not within a specified range (open or short), a malfunction is detected and a DTC is stored.
A/T clutch pressure control solenoid valve C is used for clutch pressure control and lock-up control. A spool in A/T clutch pressure control solenoid valve C pushes a valve according to the duty cycle that is controlled by the powertrain control module (PCM) so the hydraulic pressure is proportional to the current. The PCM measures the current flowing through A/T clutch pressure control solenoid valve C and uses feedback control to compensate for the difference between the actual current and the commanded one. If the measured current for the PCM output duty cycle is not within a specified range (open or short), a malfunction is detected and a DTC is stored.
A/T clutch pressure control solenoid valve C is used for clutch pressure control and lock-up control. A spool in A/T clutch pressure control solenoid valve C pushes a valve according to the duty cycle that is controlled by the powertrain control module (PCM) so the hydraulic pressure is proportional to the current. The PCM measures the current flowing through A/T clutch pressure control solenoid valve C and uses feedback control to compensate for the difference between the actual current and the commanded one. If the measured current for the PCM output duty cycle is not within a specified range (open or short), a malfunction is detected and a DTC is stored.
When shift solenoid valves A, B, and C are turned ON, the hydraulic pressure circuit opens. The hydraulic pressure circuit supplies/discharges hydraulic pressure to/from each clutch according to the combination of the ON/OFF status of those valves and the shift valves. The powertrain control module (PCM) commands the driver circuit to turn on the shift solenoid valve. The circuit diagnoses malfunctions such as a circuit short or open, and sends back a return signal during the PCM's command. When the return signal does not match the PCM command, a malfunction is detected by the PCM. The malfunction is detected when the return signal does not match the PCM command to turn ON the shift solenoid valve, and a DTC is stored.
When shift solenoid valves A, B, and C are turned ON, the hydraulic pressure circuit opens. The hydraulic pressure circuit supplies/discharges hydraulic pressure to/from each clutch according to the combination of the ON/OFF status of those valves and the shift valves. The powertrain control module (PCM) commands the driver circuit to turn on the shift solenoid valve. The circuit diagnoses malfunctions such as a circuit short or open, and sends back a return signal during the PCM's command. When the return signal does not match the PCM command, a malfunction is detected by the PCM. The malfunction is detected when the return signal does not match the PCM command to turn OFF the shift solenoid valve, and a DTC is stored.
When shift solenoid valves A, B, and C are turned ON, the hydraulic pressure circuit opens. The hydraulic pressure circuit supplies/discharges hydraulic pressure to/from each clutch according to the combination of the ON/OFF status of those valves and the shift valves. The powertrain control module (PCM) commands the driver circuit to turn on the shift solenoid valve. The circuit diagnoses malfunctions such as a circuit short or open, and sends back a return signal during the PCM's command. When the return signal does not match the PCM command, a malfunction is detected by the PCM. The malfunction is detected when the return signal does not match the PCM command to turn ON the shift solenoid valve, and a DTC is stored.
When shift solenoid valves A, B, and C are turned ON, the hydraulic pressure circuit opens. The hydraulic pressure circuit supplies/discharges hydraulic pressure to/from each clutch according to the combination of the ON/OFF status of those valves and the shift valves. The powertrain control module (PCM) commands the driver circuit to turn on the shift solenoid valve. The circuit diagnoses malfunctions such as a circuit short or open, and sends back a return signal during the PCM's command. When the return signal does not match the PCM command, a malfunction is detected by the PCM. The malfunction is detected when the return signal does not match the PCM command to turn OFF the shift solenoid valve, and a DTC is stored.
When shift solenoid valves A, B, and C are turned ON, the hydraulic pressure circuit opens. The hydraulic pressure circuit supplies/discharges hydraulic pressure to/from each clutch according to the combination of the ON/OFF status of those valves and the shift valves. The powertrain control module (PCM) commands the driver circuit to turn on the shift solenoid valve. The circuit diagnoses malfunctions such as a circuit short or open, and sends back a return signal during the PCM's command. When the return signal does not match the PCM command, a malfunction is detected by the PCM. The malfunction is detected when the return signal does not match the PCM command to turn ON the shift solenoid valve, and a DTC is stored.
When shift solenoid valves A, B, and C are turned ON, the hydraulic pressure circuit opens. The hydraulic pressure circuit supplies/discharges hydraulic pressure to/from each clutch according to the combination of the ON/OFF status of those valves and the shift valves. The powertrain control module (PCM) commands the driver circuit to turn on the shift solenoid valve. The circuit diagnoses malfunctions such as a circuit short or open, and sends back a return signal during the PCM's command. When the return signal does not match the PCM command, a malfunction is detected by the PCM. The malfunction is detected when the return signal does not match the PCM command to turn OFF the shift solenoid valve, and a DTC is stored.
The intake manifold tuning (IMT) system controls engine output by selecting either long or short intake runner lengths. The system consists of the IMT valve, the IMT actuator, and the powertrain control module (PCM). The IMT actuator is attached to the intake manifold and it includes the motor and the Hall-effect-IC position sensing unit. The PCM actuates the motor, which operates the IMT valve. When the IMT valve is closed, the long runner is selected, increasing torque at low engine speed. When the IMT valve is open, the short runner is selected, increasing torque at high engine speed. A Hall-effect-IC position sensing unit is integrated with the motor to provide precise open/close feedback to the PCM. The IMT actuator sends a long runner return signal to the PCM when the IMT valve is closed, and it sends a short runner return signal when the IMT valve is open.
If the PCM receives no closed return signal when it sends a close command, or if it receives no open return signal when sending an open command to the IMT actuator, for a specified time, it detects a malfunction and stores a DTC.
The intake manifold tuning (IMT) system controls engine output by selecting either long or short intake runner lengths. The system consists of the IMT valve, the IMT actuator, and the powertrain control module (PCM). The IMT actuator is attached to the intake manifold and it includes the motor and the Hall-effect-IC position sensing unit. The PCM actuates the motor, which operates the IMT valve. When the IMT valve is closed, the long runner is selected, increasing torque at low engine speed. When the IMT valve is open, the short runner is selected, increasing torque at high engine speed. A Hall-effect-IC position sensing unit is integrated with the motor to provide precise open/close feedback to the PCM. The IMT actuator sends a long runner return signal to the PCM when the IMT valve is closed, and it sends a short runner return signal when the IMT valve is open.
If the PCM receives no closed return signal when it sends a close command, or if it receives no open return signal when sending an open command to the IMT actuator, for a specified time, it detects a malfunction and stores a DTC.
The barometric pressure (BARO) sensor is built into the powertrain control module (PCM) and monitors atmospheric pressure. The PCM estimates appropriate intake airflow from the manifold absolute pressure (MAP) sensor output voltage and BARO sensor output voltage. When BARO sensor output voltage is within the specified range, a malfunction is detected and a DTC is stored.
Two engine coolant temperature sensors and one intake air temperature sensor are used by the powertrain control module (PCM).
When the engine stops and enough time has passed, the temperature of the engine will equal the ambient temperature. When an inappropriate temperature is detected after comparing the temperature readings of each sensor, a malfunction in the corresponding sensor is detected and a DTC is stored.
The manifold absolute pressure (MAP) sensor senses manifold absolute pressure (vacuum) and converts it into electrical signals. The MAP sensor outputs low signal voltage at high-vacuum (idling) and high signal voltage at low-vacuum (throttle valve wide open).
The powertrain control module (PCM) compares a predetermined MAP value at a given throttle position and manifold absolute pressure to the output voltage value of the MAP sensor.
If the MAP sensor outputs lower voltage than expected, the PCM detects a malfunction and stores a DTC.
The manifold absolute pressure (MAP) sensor senses manifold absolute pressure (vacuum) and converts it into electrical signals. The MAP sensor outputs low signal voltage at high-vacuum (throttle valve closed) and high signal voltage at low-vacuum (throttle valve wide open).
The powertrain control module (PCM) compares a predetermined MAP value at a given throttle position and manifold absolute pressure to the output voltage value of the MAP sensor.
If the MAP sensor outputs high voltage during fuel cut-off operation for deceleration with the throttle valve fully closed, which should make the manifold absolute pressure lower, the PCM detects a malfunction and stores a DTC.
The electrical load detector (ELD) is built into the under-hood fuse/relay box. It monitors the current fed to the ignition switch and sends a signal to the powertrain control module (PCM). If the ELD output voltage is extremely low, a malfunction is detected and a DTC is stored.
The electrical load detector (ELD) is built into the under-hood fuse/relay box. It monitors the current fed to the ignition switch and sends a signal to the powertrain control module (PCM). If the ELD output voltage is extremely high, a malfunction is detected and a DTC is stored.
The fuel tank pressure is about 0 kPa (0 mmHg, 0 in.Hg) when starting a cold engine. When the fuel tank pressure (FTP) sensor output value is out of a specified range and the powertrain control module (PCM) judges that there's no other cause [no evaporative emission (EVAP) canister vent shut valve failure, etc.] of the FTP sensor zero point shift, the PCM detects an FTP sensor malfunction.
However, if the FTP sensor output when starting the engine is a prescribed negative value or less (excessive negative pressure is detected), the malfunction judgment should be done as follows because it is difficult to distinguish the FTP sensor zero point shift (P1454) from the EVAP canister vent shut valve failure (P2422).
- If either Temporary DTC P1454 or P2422 is not stored, the PCM stores both DTCs.
- If both P1454 and P2422 Temporary DTCs are stored and an excessive negative pressure is detected, both P1454 and P2422 DTCs are stored.
- If either Temporary DTC P1454 or P2422 is stored and an excessive negative pressure is detected, the PCM stores the DTC of the temporary DTC that was stored.
The alternator is driven by the engine and generates electricity to supply the necessary power to the electrical system and to charge the battery. The alternator voltage target values of 14.5 V and 12.5 V are achieved by switching the alternator control mode (controlled by the powertrain control module (PCM)). The alternator output signal is sent to the PCM, and it varies according to the battery's state of charge, the electrical load, and engine rpm.
When the IGP (power source) terminal voltage is a set value or less and this condition continues for a set time, the PCM detects a malfunction and a DTC is stored.
The powertrain control module (PCM) controls the throttle valve opening. The system is composed of the throttle actuator, the throttle valve, throttle position (TP) sensors A and B, the accelerator pedal position (APP) sensor, the electronic throttle control system (ETCS) control relay, and the PCM.
The APP sensor is operated via the throttle cable to determine the accelerator opening value when the driver presses the accelerator pedal. The accelerator pedal opening value is converted to a signal in the APP sensor and transmitted to the PCM to compute the target position.
The PCM determines the throttle valve target position according to the signal received and operates the throttle actuator to move the throttle valve to the target position. The actual throttle valve position is determined by TP sensor A installed in the throttle body.
When the voltage is applied from the ETCS control relay to the IG1ETCS terminal for a set time after the ETCS control relay is turned off, the PCM detects a malfunction in the ETCS control relay power switch and a DTC is stored.
The powertrain control module (PCM) controls the throttle valve opening. The system is composed of the throttle actuator, the throttle valve, throttle position (TP) sensors A and B, the accelerator pedal position (APP) sensor, the electronic throttle control system (ETCS) control relay, and the PCM.
The APP sensor is operated via the throttle cable to determine the accelerator opening value when the driver presses the accelerator pedal. The accelerator pedal opening value is converted to a signal in the APP sensor and transmitted to the PCM to compute the target position.
The PCM determines the throttle valve target position according to the signal received and operates the throttle actuator to move the throttle valve to the target position. The actual throttle valve position is determined by TP sensor A installed in the throttle body.
When the voltage from the ETCS control relay is not input for a set time after the ETCS control relay is turned on when the ignition is turned on, or when voltage is not applied for a set time when the throttle actuator is operating, a malfunction in the ETCS control relay power switch is detected and a DTC is stored.
The electronic throttle control system (ETCS) controls the throttle valve opening. The system is composed of the throttle actuator, the throttle valve, throttle position (TP) sensors A and B, the throttle actuator control module, the throttle actuator control module relay, the accelerator pedal position (APP) sensor, and the powertrain control module (PCM).
The throttle valve default position spring is attached to the throttle valve gear. It opens the throttle valve to improve starting performance in cold conditions, or to retain minimum running performance in case of an electronic throttle control system failure. If the throttle valve does not return to the default position when the throttle actuator control module moves the throttle actuator to the default position from the fully closed position, a malfunction is detected and the malfunction data is transmitted to the PCM. When the PCM receives the malfunction data from the throttle actuator control module, the PCM detects the malfunction of the throttle valve default position spring and a DTC is stored.
The electronic throttle control system (ETCS) controls the throttle valve opening. The system is composed of the throttle actuator, the throttle valve, throttle position (TP) sensors A and B, the throttle actuator control module, the throttle actuator control module relay, the accelerator pedal position (APP) sensor, and the powertrain control module (PCM). The throttle valve return spring is attached to the throttle valve gear to return the throttle valve to the default position. If the throttle valve does not return to the default position when the throttle actuator control module moves the throttle actuator to the default position from the middle position, a malfunction is detected and the malfunction data is transmitted to the PCM. When the PCM receives the malfunction data from the throttle actuator control module, the PCM detects the malfunction of the throttle valve return spring and a DTC is stored.
The alternator is driven by the engine and generates electricity to supply the necessary power to the electrical system and to charge the battery. The alternator voltage target values of 14.5 V and 12.5 V are achieved by switching the alternator control mode (controlled by the powertrain control module (PCM)). The alternator output signal is sent to the PCM, and it varies according to the battery's state of charge, the electrical load, and the engine rpm.
When the engine speed is a specified value and the IGP terminal voltage is below a set value when the alternator is in the 14.5 V mode, and the alternator power generation amount is within the set range, and this condition continues more than a set time, the PCM detects a malfunction and a DTC is stored.
The alternator is driven by the engine and generates electricity to supply the necessary power to the electrical load and to charge the battery. The alternator voltage target values of 14.5 V and 12.5 V are achieved by switching the alternator control mode (controlled by the powertrain control module (PCM)). The alternator output signal is sent to the PCM, and it varies according to the battery's state of charge, the electrical load, and the engine rpm. When the engine speed is a specified value and the IGP terminal voltage is below a set value when the alternator is in the 14.5 V mode, and the alternator power generation amount is a set range or less, and this condition continues more than a set time, the PCM detects a malfunction and a DTC is stored.
The electronic throttle control system (ETCS) controls the throttle valve opening. The system is composed of the throttle actuator, the throttle valve, throttle position (TP) sensors A and B, the throttle actuator control module, the throttle actuator control module relay, the accelerator pedal position (APP) sensor, and the powertrain control module (PCM). The accelerator pedal position (APP) sensor is operated via the throttle cable to determine the accelerator opening value when the driver presses the accelerator pedal. The accelerator pedal opening value is converted to a signal in the APP sensor and transmitted to the PCM to compute the target position. The target position signal is then transmitted to the throttle actuator control module.
The throttle actuator control module determines the throttle valve target position according to the signal received and operates the throttle actuator to move the throttle valve to the target position. The actual throttle valve position is determined by TP sensor A installed in the throttle body.
The throttle actuator control module compares the throttle valve target opening angle and the actual throttle valve opening angle from TP sensor A, and when the difference exceeds the specification, the throttle actuator control module transmits the malfunction data to the PCM. When the PCM receives the malfunction data from the throttle actuator control module, the PCM detects the malfunction of the throttle actuator system and a DTC is stored.
The electronic throttle control system (ETCS) controls the throttle valve opening. The system is composed of the throttle actuator, the throttle valve, throttle position (TP) sensors A and B, the throttle actuator control module, the throttle actuator control module relay, the accelerator pedal position (APP) sensor, and the powertrain control module (PCM).
The APP sensor is operated via the throttle cable to determine the accelerator opening value when the driver presses the accelerator pedal. The accelerator pedal opening value is converted to a signal in the APP sensor and transmitted to the PCM to compute the target position. The target position signal is then transmitted to the throttle actuator control module. The throttle actuator control module determines the throttle valve target position according to the signal received and operates the throttle actuator to move the throttle valve to the target position. The actual throttle valve position is determined by TP sensor A installed in the throttle body.
When the output current to the throttle actuator exceeds the specification for a set time, the throttle actuator control module detects a malfunction and transmits the malfunction data to the PCM. When the PCM receives the malfunction data from the throttle actuator control module, the PCM detects a malfunction of the throttle actuator system and stores a DTC.
Accelerator pedal position (APP) sensor A is a part of the electronic throttle control system, and it is used to convert the position of the accelerator pedal into electrical signals. Based on these signals, the powertrain control module (PCM) controls the throttle actuator so that the throttle position agrees with the accelerator pedal position. If the signal voltage from APP sensor A is a set value or less, the PCM detects a malfunction and stores a DTC.
Accelerator pedal position (APP) sensor A is a part of the electronic throttle control system, and it is used to convert the position of the accelerator pedal into electrical signals. Based on these signals, the powertrain control module (PCM) controls the throttle actuator so that the throttle position agrees with the accelerator pedal position. If the signal voltage from APP sensor A is a set value or more, the PCM detects a malfunction and stores a DTC.
Accelerator pedal position (APP) sensor B is a part of the electronic throttle control system, and it is used to convert the position of the accelerator pedal into electrical signals. Based on these signals, the powertrain control module (PCM) controls the throttle actuator so that the throttle position agrees with the accelerator pedal position. If the signal voltage from APP sensor B is a set value or less, the PCM detects a malfunction and stores a DTC.
Accelerator pedal position (APP) sensor B is a part of the electronic throttle control system, and it is used to convert the position of the accelerator pedal into electrical signals. Based on these signals, the powertrain control module (PCM) controls the throttle actuator so that the throttle position agrees with the accelerator pedal position. If the signal voltage from APP sensor B is a set value or more, the PCM detects a malfunction and stores a DTC.
The powertrain control module (PCM) controls the throttle valve opening. The system is composed of the throttle actuator, the throttle valve, throttle position (TP) sensors A and B, the accelerator pedal position (APP) sensor, and the PCM. The APP sensor is operated via the throttle cable to determine the accelerator opening value when the driver presses the accelerator pedal. The accelerator pedal opening value is converted to a signal in the APP sensor and transmitted to the PCM to compute the target position.
The PCM determines the throttle valve target position according to the signal received and operates the throttle actuator to move the throttle valve to the target position. The actual throttle valve position is determined by TP sensor A, installed in the throttle body.
The PCM compares the voltages and the throttle valve positions of TP sensor A and TP sensor B. If the difference of the voltages or the throttle valve positions is a fixed value or below for a set time, the PCM detects a malfunction in the relationship between TP sensor A and TP sensor B, and stores a DTC.
Accelerator pedal position (APP) sensor A and accelerator pedal position (APP) sensor B are potentiometers, and they are installed in the engine compartment.
Accelerator pedal position (APP) sensors A and B are operated via the throttle cable to determine the accelerator opening value when the driver presses the accelerator pedal. The accelerator pedal opening value is converted to a signal in APP sensors A and B and transmitted to the powertrain control module (PCM) to compute the target position. The target position signal is transmitted to the throttle actuator control module via the circuit.
APP sensor A is for the primary control, and APP sensor B is a back-up of APP sensor A in case it malfunctions. Both sensors compare their output voltage to each other for malfunction detection. When the voltage difference of APP sensor B is out of a fixed range for a set time, the PCM detects a malfunction, and a DTC is stored.
The electronic throttle control system (ETCS) controls the throttle valve opening. The system is composed of the throttle actuator, the throttle valve, throttle position (TP) sensors A and B, the throttle actuator control module, the throttle actuator control module relay, the accelerator pedal position (APP) sensor, and the powertrain control module (PCM).
The APP sensor is operated via the throttle cable to determine the accelerator opening value when the driver presses the accelerator pedal. The accelerator pedal opening value is converted to a signal in the APP sensor and transmitted to the PCM to compute the target position. The target position signal is then transmitted to the throttle actuator control module. The throttle actuator control module determines the throttle valve target position according to the signal received and operates the throttle actuator to move the throttle valve to the target position. The actual throttle valve position is determined by TP sensor A installed in the throttle body.
The throttle actuator control module transmits a signal to the throttle actuator and moves the throttle valve to the fully closed position to register the throttle valve fully closed position after the ignition switch is turned ON.
The throttle actuator control module detects the malfunction of the throttle actuator control system, and it transmits a malfunction signal to the PCM when the registration of the throttle valve fully closed position is not completed within a predetermined time or the registered value is out of predetermined range after the ignition switch is turned ON. When the PCM receives the malfunction data from the throttle actuator control module, the PCM detects a malfunction in the throttle actuator control system and stores a DTC.
Two engine coolant temperature sensors and one intake air temperature sensor are used by the powertrain control module (PCM).
When the engine stops and enough time has passed, the temperature of the engine will equal the ambient temperature. When an inappropriate temperature is detected after comparing the temperature readings of each sensor, a malfunction in the corresponding sensor is detected and a DTC is stored.
Engine coolant temperature (ECT) sensor 2 is a thermistor attached to the water passage. The powertrain control module (PCM) applies voltage (about 5 V) to the ECT2 signal circuit through a pull-up resistor. As the engine coolant temperature cools, ECT sensor 2 resistance increases, and the PCM detects a high signal voltage. As the engine coolant warms, the sensor resistance decreases, and the PCM detects a low ECT2 signal voltage.
If the ECT sensor 2 output voltage is less than a set value when the engine coolant temperature is high, the PCM detects a malfunction and a DTC is stored.
Engine coolant temperature (ECT) sensor 2 is a thermistor attached to the water passage. The powertrain control module (PCM) applies voltage (about 5 V) to the ECT2 signal circuit through a pull-up resistor. As the engine coolant temperature cools, ECT sensor 2 resistance increases, and the PCM detects a high signal voltage. As the engine coolant warms, the sensor resistance decreases, and the PCM detects a low ECT2 signal voltage.
If the ECT sensor 2 output voltage is more than a set value when the engine coolant temperature is low, the PCM detects a malfunction and a DTC is stored.
The barometric pressure (BARO) sensor is built into the powertrain control module (PCM) and monitors atmospheric pressure. When the throttle valve is wide open, the manifold absolute pressure (MAP) sensor output is nearly equal to the BARO sensor output. Making use of this characteristic, a malfunction can be detected in the BARO sensor output. If the throttle position is beyond a value stored in the PCM that is used to detect "wide-open throttle," and if the difference between the MAP sensor output and the BARO sensor output is equal to or greater than a set value, a malfunction in the BARO sensor output is detected and a DTC is stored.
The barometric pressure (BARO) sensor is built into the powertrain control module (PCM) and monitors atmospheric pressure. The PCM estimates appropriate intake airflow from the manifold absolute pressure (MAP) sensor output voltage and BARO sensor output voltage. If the BARO sensor output voltage is a specified value or less, the PCM detects a malfunction and a DTC is stored.
The barometric pressure (BARO) sensor is built into the powertrain control module (PCM) and monitors atmospheric pressure. The PCM estimates appropriate intake airflow from the manifold absolute pressure (MAP) sensor output voltage and BARO sensor output voltage. If the BARO sensor output voltage is a specified value or more, the PCM detects a malfunction and a DTC is stored.
The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The rear A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the rear A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. If the IPB1 terminal voltage is out of a specified range, the PCM detects a malfunction and stores a DTC.
The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The rear A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the rear A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control.
If the IPB1 terminal voltage is a specified value or less, the PCM detects a malfunction and stores a DTC.
The front air/fuel ratio (A/F) sensor (bank 2, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The front A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the front A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control.
If the IPB2 terminal voltage is out of a specified range, the PCM detects a malfunction and stores a DTC.
The front air/fuel ratio (A/F) sensor (bank 2, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The front A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the front A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. If the IPB2 terminal voltage is a specified value or less, the PCM detects a malfunction and stores a DTC.
The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The rear A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the rear A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control.
When the VSB1 terminal voltage repeatedly fluctuates between a value above the specification and a value below the specification at a certain frequency, the PCM detects a malfunction and a DTC is stored.
The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The rear A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the rear A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. If the IPB1 terminal voltage is a specified value or more, and the VCENTB1 terminal voltage is less than the specified value, the PCM detects a malfunction and stores a DTC.
The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The rear A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the rear A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control.
When the VSB2 terminal voltage repeatedly fluctuates between a value above the specification and a value below the specification at a certain frequency, the PCM detects a malfunction and a DTC is stored.
The front air/fuel ratio (A/F) sensor (bank 2, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The front A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the front A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. If the IPB2 terminal voltage is a specified value or more, and the VCENTB2 terminal voltage is less than the specified value, the PCM detects a malfunction and stores a DTC.
The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The rear A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the rear A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. When the VSB1 terminal voltage and the PCM internal signal voltage are more than a specified value for more than a predetermined time, the PCM detects a malfunction and a DTC is stored.
The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The rear A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the rear A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. When the VSB1 terminal voltage is less than the specified value and the IPB1 terminal voltage is more than the specified value for more than a set time, the PCM detects a malfunction and a DTC is stored.
The front air/fuel ratio (A/F) sensor (bank 2, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The front A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the front A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. When the VSB2 terminal voltage and the PCM internal signal voltage are more than a specified value for more than a predetermined time, the PCM detects a malfunction and a DTC is stored.
The front air/fuel ratio (A/F) sensor (bank 2, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The front A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the front A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. When the VSB2 terminal voltage is less than the specified value and the IPB2 terminal voltage is more than the specified value for more than a set time, the PCM detects a malfunction and a DTC is stored.
The positive crankcase ventilation (PCV) system reduces hydrocarbons (HC). The PCV system recirculates unburned air/ fuel mixture (blow-by vapor) into the intake manifold so that it is drawn into the engine and burned, thus reducing HC. If the PCV hose comes off while air is supplied mainly via the idle control system with the throttle closed, the amount of air supplied to the engine is considerably more than the amount of air the idle control system supplies. The powertrain control module (PCM) estimates the amount of air supplied to the engine while the throttle valve is fully closed, and if the estimated amount is more than the upper limit, it detects a malfunction and a DTC is stored.
The exhaust gas recirculation (EGR) valve, which is controlled by the powertrain control module (PCM), is opened and the exhaust gas flows from the exhaust manifold through the EGR valve and the intake manifold and the EGR passage. The exhaust gas is circulated into the air/fuel mixture and the mixture is drawn into the combustion chamber to lower the combustion temperatures, thus reducing oxides of nitrogen (NOx) emissions.
A sensor (lift sensor) is built into the EGR valve and detects the amount of valve lift. The command value for the target valve lift is stored in the PCM so that exhaust gas recirculation can be optimized according to driving conditions.
Comparing this command value with the lift sensor output signal value, the PCM controls the EGR valve to make the amount of actual valve lift equal to the command value.
If the valve sensor output is insufficient for the commanded valve lift, a malfunction is detected.
The fuel tank pressure (FTP) sensor output indicates about atmospheric pressure 0 kPa (0 mmHg, 0 in.Hg) before purge starts since the evaporative emission (EVAP) canister vent shut valve is normally open (open to the atmosphere). The sensor indicates a negative pressure value (vacuum) during purging.
When the FTP sensor indicates vacuum after starting the engine, there is the possibility of an FTP sensor zero point shift failure or an EVAP canister vent shut valve stuck closed failure. So the powertrain control module (PCM) monitors the FTP sensor output after purge starts. The PCM detects a malfunction of the EVAP canister vent shut valve if the output indicates excessive vacuum.
However, if the fuel tank internal pressure is below the specified value (excessive vacuum is detected) when starting the engine, the malfunction detection should be done as follows because it is difficult to distinguish the FTP sensor range problem (P1454) from the EVAP canister vent shut valve stuck closed (P2422).
- If neither Temporary DTC (P1454 nor P2422) is stored, both DTCs are stored.
- If both Temporary DTCs (P1454 and P2422) are stored and excessive vacuum is detected, both DTCs are stored.
- If either Temporary DTC (P1454 or P2422) is stored and excessive vacuum is detected, the PCM stores the DTC of the Temporary DTC that was stored.
The powertrain control module (PCM) has a built-in power off timer that measures the duration of time the ignition switch is off. This measurement is used for evaporative emission (EVAP) leak detection and temperature assumption of the catalytic converter.
The CPU in the PCM accesses the power off timer when reading the measured duration. When the access process fails, a malfunction is detected and a DTC is stored. When an abnormality is found in the read data, a malfunction is detected and a DTC is stored.
The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The rear A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the rear A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. The rear A/F sensor (bank 1, sensor 1) has a built-in LABEL resistance to regulate the difference of the sensor characteristics. The PCM reads the resistance to regulate the difference properly. If the LABEL resistance (VLBLB1 signal voltage) is a set value or less, the PCM detects a malfunction and stores a DTC.
The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The rear A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the rear A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. The rear A/F sensor (bank 1, sensor 1) has a built-in LABEL resistance to regulate the differences of the sensor characteristics. The PCM reads the resistance to regulate the difference properly. If the LABEL resistance (VLBLB1 signal voltage) is a set value or more, the PCM detects a malfunction and stores a DTC.
The front air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The front A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the front A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. The front A/F sensor (bank 1, sensor 1) has a built-in LABEL resistance to regulate the differences of the sensor characteristics. The PCM reads the resistance to regulate the difference properly. If the LABEL resistance (VLBLB2 signal voltage) is a set value or less, the PCM detects a malfunction and stores a DTC.
The front air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold and detects oxygen content in the exhaust gas. The front A/F sensor transmits a signal to the powertrain control module (PCM). The PCM controls fuel injection duration by comparing the target air/fuel ratio with the front A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. The front A/F sensor (bank 1, sensor 1) has a built-in LABEL resistance to regulate the differences of the sensor characteristics. The PCM reads the resistance to regulate the difference properly. If the LABEL resistance (VLBLB2 signal voltage) is a set value or more, the PCM detects a malfunction and stores a DTC.
The VTEC system activates the VTEC solenoid valve by command from the powertrain control module (PCM), and it charges/discharges the hydraulic circuit of the VTEC mechanism that switches valve timing between Low and High. The PCM monitors oil pressure in the hydraulic circuit of the VTEC mechanism using the VTEC oil pressure switch downstream of the VTEC solenoid valve. If there is a difference between the oil pressure condition in the hydraulic circuit that is determined by the PCM command and the oil pressure condition that is determined by the status of the VTEC oil pressure switch, the system is considered faulty, and a DTC is stored.
The VTEC system activates the VTEC solenoid valve by command from the powertrain control module (PCM), and it charges/discharges the hydraulic circuit of the VTEC mechanism that switches valve timing between Low and High. The PCM monitors oil pressure in the hydraulic circuit of the VTEC mechanism using the VTEC oil pressure switch downstream of the VTEC solenoid valve. If there is a difference between the oil pressure condition in the hydraulic circuit that is determined by the PCM command and the oil pressure condition that is determined by the status of the VTEC oil pressure switch, the system is considered faulty, and a DTC is stored.
The VTEC system activates the rocker arm oil control solenoid (VTEC solenoid valve) by command from the powertrain control module (PCM), and it charges/discharges the hydraulic circuit of the VTEC mechanism that switches valve timing between low and high. If the return signal is OFF (low) when the PCM outputs the ON (high) signal to the rocker arm oil control solenoid (VTEC solenoid valve), the PCM detects a malfunction and a DTC is stored.
The VTEC system activates the rocker arm oil control solenoid (VTEC solenoid valve) by command from the powertrain control module (PCM), and it charges/discharges the hydraulic circuit of the VTEC mechanism that switches valve timing between low and high. If the return signal is ON (high) when the PCM outputs the OFF (low) signal to the rocker arm oil control solenoid (VTEC solenoid valve), the PCM detects a malfunction and a DTC is stored.
The torque converter clutch solenoid valve switches the hydraulic circuit to engage/disengage the torque converter clutch. When the torque converter clutch solenoid valve is turned ON, hydraulic pressure is applied to the torque converter clutch. When the torque converter clutch solenoid valve is turned OFF, hydraulic pressure to the torque converter clutch is interrupted. The powertrain control module (PCM) commands the driver circuit to turn on the torque converter clutch solenoid valve. The circuit diagnoses malfunctions such as a circuit short or open, and sends back a return signal during the PCM's command. When the return signal does not match the PCM command, a malfunction is detected by the PCM. The malfunction is detected when the return signal does not match the PCM command to turn ON the torque converter clutch solenoid valve, and a DTC is stored.
The torque converter clutch solenoid valve switches the hydraulic circuit to engage/disengage the torque converter clutch. When the torque converter clutch solenoid valve is turned ON, hydraulic pressure is applied to the torque converter clutch. When the torque converter clutch solenoid valve is turned OFF, hydraulic pressure to the torque converter clutch is interrupted. The powertrain control module (PCM) commands the driver circuit to turn on the torque converter clutch solenoid valve. The circuit diagnoses malfunctions such as a circuit short or open, and sends back a return signal during the PCM's command. When the return signal does not match the PCM command, a malfunction is detected by the PCM. The malfunction is detected when the return signal does not match the PCM command to turn OFF the torque converter clutch solenoid valve, and a DTC is stored.
The controller area network (CAN) transmits/receives pulsing signals to/from the control modules simultaneously by using two signal lines (CANH and CANL).
When the powertrain control module (PCM) does not receive the signals via the CAN lines for a set time or more, the PCM detects a malfunction and a DTC is stored.
The controller area network (CAN) transmits/receives pulsing signals to/from the control modules simultaneously by using two signal lines (CANH and CANL).
When the powertrain control module (PCM) does not receive the signals via the CAN lines for more than a set time, the PCM detects a malfunction and a DTC is stored.
The controller area network (CAN) transmits/receives pulsing signals to/from the control modules simultaneously by using two signal lines (CANH and CANL).
When the powertrain control module (PCM) does not receive the signals via the CAN lines for more than a set time, the PCM detects a malfunction and a DTC is stored.
The controller area network (CAN) transmits/receives pulsing signals to/from the control modules simultaneously by using two signal lines (CANH and CANL).
When the powertrain control module (PCM) does not receive the signals from the gauge control module via the CAN lines for a set time or more, the PCM detects a malfunction and a DTC is stored.