Engine Control System (Diagnostic Codes (P0171-U0560): Overview Scion FR-S I

DESCRIPTION

The fuel trim is related to the feedback compensation value, not to the basic injection time. The fuel trim consists of both the short-term and the long-term fuel trim.

The short-term fuel trim is fuel compensation that is used to constantly maintain the air fuel ratio at stoichiometric levels. The signal from the air fuel ratio sensor indicates whether the air fuel ratio is rich or lean compared to the stoichiometric ratio. This triggers a reduction in the fuel injection volume if the air fuel ratio is rich and an increase in the fuel injection volume if it is lean.

Factors such as individual engine differences, wear over time and changes in operating environment cause short-term fuel trim to vary from the ideal theoretical value. The long-term fuel trim controls overall fuel compensation. The long-term fuel trim compensates for long term deviations of the fuel trim from the ideal theoretical value. These long term deviations result from the corrections made by the short-term fuel trim.

If both the short-term fuel and long-term fuel trim are lean or rich beyond predetermined values, it is interpreted as a malfunction, the ECM illuminates the MIL and sets a DTC.

HINT

1. When DTC P0171 is set, the actual air-fuel ratio is on the lean side. When DTC P0172 is set, the actual air-fuel ratio is on the rich side.
2. If the vehicle runs out of fuel, the air-fuel ratio is lean and DTC P0171 may be set. The MIL is then illuminated.
3. When DTC P1170 or P117B is output, it may not be possible to precisely determine whether the port injection or the direct injection is malfunctioning, depending on the conditions. In this case, perform an Active Test (control the injection way) to determine which injection system is malfunctioning.

MONITOR DESCRIPTION

Under closed loop fuel control, fuel injection volumes that deviate from those estimated by the ECM cause changes in the long-term fuel trim compensation value. The long-term fuel trim is adjusted when there are persistent deviations in the short-term fuel trim values. Deviations from the ECM's estimated fuel injection volumes also affect the average fuel trim learning value, which is a combination of the average short-term fuel trim (fuel feedback compensation value) and the average long-term fuel trim (learning value of the air fuel ratio). If the average fuel trim learning value exceeds the malfunction threshold, the ECM interprets this as a malfunction in the fuel system and sets a DTC.

The fuel trim is related to the feedback compensation value, not to the basic injection time. The fuel trim consists of both the short-term and the long-term fuel trim.

The short-term fuel trim is fuel compensation that is used to constantly maintain the air fuel ratio at stoichiometric levels. The signal from the air fuel ratio sensor indicates whether the air fuel ratio is rich or lean compared to the stoichiometric ratio. This triggers a reduction in the fuel injection volume if the air fuel ratio is rich and an increase in the fuel injection volume if it is lean.

Factors such as individual engine differences, wear over time and changes in operating environment cause short-term fuel trim to vary from the ideal theoretical value. The long-term fuel trim controls overall fuel compensation. The long-term fuel trim compensates for long term deviations of the fuel trim from the ideal theoretical value. These long term deviations result from the corrections made by the short-term fuel trim.

If both the short-term fuel and long-term fuel trim are lean or rich beyond predetermined values, it is interpreted as a malfunction, the ECM illuminates the MIL and sets a DTC.

HINT

1. When DTC P0171 is set, the actual air-fuel ratio is on the lean side. When DTC P0172 is set, the actual air-fuel ratio is on the rich side.
2. If the vehicle runs out of fuel, the air-fuel ratio is lean and DTC P0171 may be set. The MIL is then illuminated.
3. When DTC P1170 or P117B is output, it may not be possible to precisely determine whether the port injection or the direct injection is malfunctioning, depending on the conditions. In this case, perform an Active Test (control the injection way) to determine which injection system is malfunctioning.

Under closed loop fuel control, fuel injection volumes that deviate from those estimated by the ECM cause changes in the long-term fuel trim compensation value. The long-term fuel trim is adjusted when there are persistent deviations in the short-term fuel trim values. Deviations from the ECM's estimated fuel injection volumes also affect the average fuel trim learning value, which is a combination of the average short-term fuel trim (fuel feedback compensation value) and the average long-term fuel trim (learning value of the air fuel ratio). If the average fuel trim learning value exceeds the malfunction threshold, the ECM interprets this as a malfunction in the fuel system and sets a DTC.

The fuel pressure sensor is installed on the delivery pipe. The sensor changes fuel pressure to an electrical signal and sends the signal to the ECM. Then the ECM controls the pump discharge using this feedback to maintain the fuel's target pressure. If the sensor output stops, the ECM will stop the high pressure side fuel pump and supply fuel using the low pressure side fuel pump.

HINT

After confirming DTC P0192 or P0193, use the Techstream to confirm the fuel pressure in the delivery pipe by entering the following menus: Powertrain / Engine / Data List / Fuel Press.

These DTCs are set if the fuel pressure sensor output voltage is out of the standard range. The DTCs stand for an open or short malfunction of the sensor circuit.

If these DTCs are set, the ECM enters fail-safe mode and limits the engine power. Fail-safe mode continues until the ignition switch is turned off.

The resistance of the thermistor within the oil temperature sensor changes in accordance with variations in the oil temperature. The method for connecting the oil temperature sensor and the ECM is the same as for the intake air temperature sensor.

HINT

If any DTC is stored, the ECM enters fail-safe mode. During operation of fail-safe mode, the ECM sets the engine oil temperature determined value at 70°C (158°F). Operation of fail-safe mode continues until the ECM restores normal operation.

P0196

When a cold engine start is performed and then the engine is warmed up, if the Engine oil temperature sensor value is less than specified value, it is determined that a malfunction has occurred. If this is detected in 2 consecutive driving cycles, the ECM interprets this as a malfunction in the engine oil temperature sensor and stores a DTC.

P0197, P0198

The ECM monitors the sensor voltage and uses this value to calculate the engine oil temperature. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a malfunction in the engine oil temperature sensor circuit and stores a DTC.

The resistance of the thermistor within the oil temperature sensor changes in accordance with variations in the oil temperature. The method for connecting the oil temperature sensor and the ECM is the same as for the intake air temperature sensor.

HINT

If any DTC is stored, the ECM enters fail-safe mode. During operation of fail-safe mode, the ECM sets the engine oil temperature determined value at 70°C (158°F). Operation of fail-safe mode continues until the ECM restores normal operation.

P0196

When a cold engine start is performed and then the engine is warmed up, if the Engine oil temperature sensor value is less than specified value, it is determined that a malfunction has occurred. If this is detected in 2 consecutive driving cycles, the ECM interprets this as a malfunction in the engine oil temperature sensor and stores a DTC.

P0197, P0198

The ECM monitors the sensor voltage and uses this value to calculate the engine oil temperature. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a malfunction in the engine oil temperature sensor circuit and stores a DTC.

The D-4S system has two injection systems. One is the in-cylinder direct injection system that directly injects pressurized fuel into the combustion chamber. The other is the intake port injection system. The ECM determines the percentage of in-cylinder direct injection to the intake port injection systems in accordance with the engine speed and load.

The ECM monitors the injection control of the port injector. If a malfunction is detected in the port injector circuit, the ECM cancels the injection control for the corresponding cylinder and turns on the MIL.

When a malfunction in the fuel pump control circuit (low pressure side) is detected, DTC P0230 is stored.

The fuel pump control circuit (low pressure side) consists of the ECM, fuel pump assembly and fuel pump control ECU (which operates the fuel pump assembly). Based on the engine output, the ECM determines the fuel pump speed. The speed is then converted to a duty signal and sent to the fuel pump control ECU. Based on the signal sent from the ECM, the fuel pump control ECU adjusts the fuel pump assembly operation speed among 3 settings. The fuel pump control ECU also has a self-diagnosis function. Based on the fuel pump control circuit (low pressure side) condition, the fuel pump control ECU outputs a diagnostic signal to the ECM, and the ECM determines if there is a malfunction in the fuel pump control circuit (low pressure side).

To monitor the fuel pump control circuit (low pressure side), the ECM checks the fuel pump control signal (FPC) and diagnostic signal (DI). The FPC voltage varies between approximately 0 V and approximately 12 V (duty signal). Based on the condition of the fuel pump control ECU malfunction, the DI voltage varies between approximately 0 V and approximately 12 V. The ECM then compares the variation of the FPC voltage and DI voltage, and determines if the fuel pump control circuit (low pressure side) is malfunctioning. When the ECM determines that the fuel pump control circuit (low pressure side) is malfunctioning, a DTC is stored immediately.

When a malfunction in the fuel pump control circuit (low pressure side) is detected, DTC P0230 is stored.

The fuel pump control circuit (low pressure side) consists of the ECM, fuel pump assembly and fuel pump control ECU (which operates the fuel pump assembly). Based on the engine output, the ECM determines the fuel pump speed. The speed is then converted to a duty signal and sent to the fuel pump control ECU. Based on the signal sent from the ECM, the fuel pump control ECU adjusts the fuel pump assembly operation speed among 3 settings. The fuel pump control ECU also has a self-diagnosis function. Based on the fuel pump control circuit (low pressure side) condition, the fuel pump control ECU outputs a diagnostic signal to the ECM, and the ECM determines if there is a malfunction in the fuel pump control circuit (low pressure side).

To monitor the fuel pump control circuit (low pressure side), the ECM checks the fuel pump control signal (FPC) and diagnostic signal (DI). The FPC voltage varies between approximately 0 V and approximately 12 V (duty signal). Based on the condition of the fuel pump control ECU malfunction, the DI voltage varies between approximately 0 V and approximately 12 V. The ECM then compares the variation of the FPC voltage and DI voltage, and determines if the fuel pump control circuit (low pressure side) is malfunctioning. When the ECM determines that the fuel pump control circuit (low pressure side) is malfunctioning, a DTC is stored immediately.

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high hydrocarbon concentration levels can cause an increase in exhaust emission levels. Extremely high concentrations of hydrocarbons can also cause increases in the three-way catalytic converter temperature, which may cause damage to the three-way catalytic converter. To prevent this increase in emissions and to limit the possibility of thermal damage, the ECM monitors the misfire count. When the temperature of the three-way catalytic converter reaches the point of thermal degradation, the ECM blinks the MIL. To monitor misfires, the ECM uses both the VVT sensor and the crankshaft position sensor. The VVT sensor is used to identify any misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. Misfires are counted when the crankshaft rotation speed variations exceed predetermined thresholds. If the misfire count exceeds the threshold levels, and could cause emission control system performance deterioration, the ECM illuminates the MIL and stores a DTC.

Scheme 146

When DTCs for misfiring cylinders are randomly stored, but DTC P0300 is not stored, it indicates that misfires have been detected in different cylinders at different times. DTC P0300 is only stored when several misfiring cylinders are detected at the same time.

The ECM illuminates the MIL and stores a DTC when either one of the following conditions, which could cause emission deterioration, is detected (2 trip detection logic).

1. Within the first 1000 crankshaft revolutions after the engine starts, an excessive number of misfires (approximately 20 to 50 misfires per 1000 crankshaft revolutions) occurs once.
2. An excessive number of misfires (approximately 20 to 50 misfires per 1000 crankshaft revolutions) occurs a total of 4 times.

The ECM flashes the MIL and stores a DTC when either one of the following conditions, which could cause damage to the three-way catalytic converter, is detected (2 trip detection logic).

1. At a high engine speed, a sufficient amount of misfires to damage the catalyst occurring within 200 crankshaft revolutions is detected once.
2. At a normal engine speed, a sufficient amount of misfires to damage the catalyst occurring within 200 crankshaft revolutions is detected 3 times.

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high hydrocarbon concentration levels can cause an increase in exhaust emission levels. Extremely high concentrations of hydrocarbons can also cause increases in the three-way catalytic converter temperature, which may cause damage to the three-way catalytic converter. To prevent this increase in emissions and to limit the possibility of thermal damage, the ECM monitors the misfire count. When the temperature of the three-way catalytic converter reaches the point of thermal degradation, the ECM blinks the MIL. To monitor misfires, the ECM uses both the VVT sensor and the crankshaft position sensor. The VVT sensor is used to identify any misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. Misfires are counted when the crankshaft rotation speed variations exceed predetermined thresholds. If the misfire count exceeds the threshold levels, and could cause emission control system performance deterioration, the ECM illuminates the MIL and stores a DTC.

Scheme 147

When DTCs for misfiring cylinders are randomly stored, but DTC P0300 is not stored, it indicates that misfires have been detected in different cylinders at different times. DTC P0300 is only stored when several misfiring cylinders are detected at the same time.

The ECM illuminates the MIL and stores a DTC when either one of the following conditions, which could cause emission deterioration, is detected (2 trip detection logic).

1. Within the first 1000 crankshaft revolutions after the engine starts, an excessive number of misfires (approximately 20 to 50 misfires per 1000 crankshaft revolutions) occurs once.
2. An excessive number of misfires (approximately 20 to 50 misfires per 1000 crankshaft revolutions) occurs a total of 4 times.

The ECM flashes the MIL and stores a DTC when either one of the following conditions, which could cause damage to the three-way catalytic converter, is detected (2 trip detection logic).

1. At a high engine speed, a sufficient amount of misfires to damage the catalyst occurring within 200 crankshaft revolutions is detected once.
2. At a normal engine speed, a sufficient amount of misfires to damage the catalyst occurring within 200 crankshaft revolutions is detected 3 times.

A flat-type knock sensor (non-resonant type) has a structure that can detect vibrations between approximately 5 kHz and 15 kHz.

Knock sensor is fitted onto the engine block to detect engine knocking.

The knock sensor contains a piezoelectric element which generates a voltage when it becomes deformed.

The voltage is generated when the engine block vibrates due to knocking. Any occurrence of engine knocking can be suppressed by delaying the ignition timing.

HINT

When DTC P0327, P0328, P332 or P0333 is stored, the ECM enters fail-safe mode. During fail-safe mode, the ignition timing is delayed to its maximum retardation. Fail-safe mode continues until the ignition switch is turned off.

If the output voltage transmitted by the knock sensor remains low or high for more than 1 second, the ECM interprets this as a malfunction in the sensor circuit and the ECM illuminates the MIL and sets a DTC.

The crankshaft position sensor system consists of a No. 1 crankshaft position sensor plate and Magnetoresistive Element (MRE) type sensor. The crankshaft angle sensor plate is installed on the crankshaft. The crankshaft position sensor generates 30 signals per crankshaft revolution. The ECM uses the camshaft position signal to distinguish between the cylinders, and uses the crankshaft position signal to detect the crankshaft position and engine speed.

If there is no signal from the crankshaft position sensor despite the crankshaft revolving, the ECM interprets this as a malfunction of the sensor and the ECM illuminates the MIL and sets a DTC.

The intake camshaft VVT sensors consist of a magnet and MRE (Magnetic Resistive Element).

The VVT camshaft drive gear has a sensor plate with 3 teeth on its outer circumference. When the gear rotates, changes occur in the air gaps between the sensor plate and MRE, which affects the magnetic field. As a result, the resistance of the MRE material fluctuates. The VVT sensor converts the gear rotation data to pulse signals, uses the pulse signals to determine the camshaft angle, and sends it to the ECM.

The crank angle sensor generates 30 signals for each engine speed. Based on combination of the VVT sensor signals and crankshaft position sensor signals, the ECM detects the crankshaft angle. Then the ECM uses this data to control fuel injection time and injection timing. Also, based on the crankshaft position sensor signal, the ECM detects the engine speed.

If no signal is transmitted by the VVT sensor despite the engine running, or the rotations of the camshaft and the crankshaft are not synchronized, the ECM interprets this as a malfunction of the sensor.

A Direct Ignition System (DIS) is used on this vehicle.

The DIS is a 1-cylinder ignition system in which each cylinder is ignited by one ignition coil and one spark plug is connected to the end of each secondary wiring. A powerful voltage, generated in the secondary wiring, is applied directly to each spark plug. The spark of the spark plugs passes from the center electrode to the ground electrodes.

The ECM determines the ignition timing and transmits the ignition (IGT) signals to each cylinder. Using the IGT signal, the ECM turns the power transistor inside the igniter on and off. The power transistor, in turn, switches on and off the current to the primary coil. When the current to the primary coil is cut off, a powerful voltage is generated in the secondary coil. This voltage is applied to the spark plugs, causing them to spark inside the cylinders.

Scheme 148

If the ECM receives a malfunction signal from the ECM driver IC, ECM recognizes that there is an open or short in signal line circuit between the ignition coil and ECM and stores the DTCs.

The exhaust camshaft VVT sensors consist of a magnet and MRE (Magnetic Resistive Element).

The exhaust camshaft has a sensor plate with 2 teeth on its outer circumference.

When the exhaust camshaft rotates, changes occur in the air gaps between the 2 teeth and MRE, which affects the magnet. As a result, the resistance of the MRE material fluctuates. The VVT sensor converts the exhaust camshaft rotation data to pulse signals, uses the pulse signals to determine the camshaft angle, and sends it to the ECM.

The crank angle sensor generates 30 signals for each engine speed. Based on combination of the VVT signals and NE signal, the ECM detects the crankshaft angle. Then the ECM uses this data to control fuel injection time and injection timing. Also, based on the NE signal, the ECM detects the engine speed.

If no signal is transmitted by the VVT sensor despite the engine running, or the rotations of the camshaft and the crankshaft are not synchronized, the ECM interprets this as a malfunction of the sensor and the ECM illuminates the MIL and sets a DTC.

The ECM uses sensors mounted in front of and behind the Three-Way Catalytic Converter (TWC) to monitor its efficiency.

The first sensor, the air fuel ratio sensor, sends pre-catalyst information to the ECM. The second sensor, the heated oxygen sensor, sends post-catalyst information to the ECM.

In order to detect any deterioration in the three-way catalytic converter, the ECM calculates the oxygen storage capacity of the three-way catalytic converter. This calculation is based on the voltage output of the heated oxygen sensor.

The ECM uses the oxygen storage capacity value to determine the state of the three-way catalytic converter. If any deterioration has occurred, the ECM illuminates the MIL and stores the DTC.

This system determines the deterioration of the entire catalyst system (including the front and rear catalysts), by using the oxygen storage capacity value of the front catalyst, that is more sensitive than the rear catalyst, as the representative value. Therefore, be sure to replace the front and rear catalysts together when catalyst replacement is necessary.

Scheme 149

TEXT IN ILLUSTRATION

The ECM uses diagnostic values to determine deterioration of the catalyst. If the diagnostic value exceeds a specified value, the catalyst is considered deteriorated, and the DTC is stored.

Scheme 150

The diagnostic values are based upon the catalyst monitor value (CM) calculated by changes in the air fuel ratio sensor lambda and changes in the heated oxygen sensor output voltage, and in the response rate calculated from the heated oxygen sensor response time.

Scheme 151

*: Diagnostic Value = CM X (1 + Response rate)

The ECM uses sensors mounted in front of and behind the Three-Way Catalytic Converter (TWC) to monitor its efficiency.

The first sensor, the air fuel ratio sensor, sends pre-catalyst information to the ECM. The second sensor, the heated oxygen sensor, sends post-catalyst information to the ECM.

In order to detect any deterioration in the three-way catalytic converter, the ECM calculates the oxygen storage capacity of the three-way catalytic converter. This calculation is based on the voltage output of the heated oxygen sensor.

The ECM uses the oxygen storage capacity value to determine the state of the three-way catalytic converter. If any deterioration has occurred, the ECM illuminates the MIL and stores the DTC.

This system determines the deterioration of the entire catalyst system (including the front and rear catalysts), by using the oxygen storage capacity value of the front catalyst, that is more sensitive than the rear catalyst, as the representative value. Therefore, be sure to replace the front and rear catalysts together when catalyst replacement is necessary.

The ECM uses diagnostic values to determine deterioration of the catalyst. If the diagnostic value exceeds a specified value, the catalyst is considered deteriorated, and the DTC is stored.

The diagnostic values are based upon the catalyst monitor value (CM) calculated by changes in the air fuel ratio sensor lambda and changes in the heated oxygen sensor output voltage, and in the response rate calculated from the heated oxygen sensor response time.

*: Diagnostic Value = CM X (1 + Response rate)

The description can be found in EVAP (Evaporative Emission) System. Refer to EVAP System .

The purge flow monitor runs while the engine is running. The purge flow monitor consists of 2 monitors. The 1st monitor is conducted every time and the 2nd monitor is activated if necessary.

Scheme 152

Scheme 153

1. The 1st monitor While the engine is running and the purge valve is on (open), the ECM monitors the purge flow by measuring the EVAP pressure change. If the variation in the pressure is less than threshold, the ECM begins the 2nd monitor.
2. The 2nd monitor The vent valve is turned on (closed) and the EVAP pressure is then measured. If the variation in the pressure is more than threshold, the ECM interprets this as the purge valve being stuck closed, and illuminates the MIL and stores DTC P0441 (2 trip detection logic).

The description can be found in EVAP (Evaporative Emission) System. Refer to EVAP System .

The purge flow monitor runs while the engine is running. The purge flow monitor consists of 2 monitors. The 1st monitor is conducted every time and the 2nd monitor is activated if necessary.

1. The 1st monitor While the engine is running and the purge valve is on (open), the ECM monitors the purge flow by measuring the EVAP pressure change. If the variation in the pressure is less than threshold, the ECM begins the 2nd monitor.
2. The 2nd monitor The vent valve is turned on (closed) and the EVAP pressure is then measured. If the variation in the pressure is more than threshold, the ECM interprets this as the purge valve being stuck closed, and illuminates the MIL and stores DTC P0441 (2 trip detection logic).

The description can be found in EVAP (Evaporative Emission) System. Refer to EVAP System .

Scheme 154

1. DTC P0451: Difference between canister pressure sensor output value and manifold absolute pressure sensor output value If the difference between the atmospheric pressure calculated using the canister pressure sensor and that calculated using the MAP sensor exceeds the specified value, then the ECM determines there is a canister pressure sensor abnormality. The ECM then illuminates the MIL and stores the DTC (2 trip detection logic).
2. DTC P0452: Canister pressure sensor voltage low If the canister pressure sensor voltage output (pressure) is below 0.973 V: 51.71 kPa(abs) [388 mmHg(abs)], the ECM interprets this as an open or short circuit in the canister pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and stores the DTC (1 trip detection logic).
3. DTC P0453: Canister pressure sensor voltage high If the canister pressure sensor voltage output (pressure) is 4.095 V: 108.99 kPa(abs) [818 mmHg(abs)] or more, the ECM interprets this as an open or short circuit in the canister pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and stores the DTC (1 trip detection logic).

The description can be found in EVAP (Evaporative Emission) System. Refer to EVAP System .

5 hours*1 after the ignition switch is turned off, the leak detection pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure.

HINT

*: If the enable conditions are not satisfied 5 hours after the ignition switch is turned off, the monitor check starts 2 hours later. If the enable conditions are still not satisfied 7 hours after the ignition switch is turned off, the monitor check starts 2.5 hours later.

*: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize.

Scheme 155

TEXT IN ILLUSTRATION

Scheme 156

1. (a) P0455: EVAP (Evaporative Emission) gross leak In operation D, the leak detection pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than [second reference pressure x 0.377] (near atmospheric pressure), the ECM determines that the EVAP system has a large leak, illuminates the MIL and stores the DTC (2 trip detection logic).
2. (b) P0456: EVAP very small leak In operation D, the leak detection pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than second reference pressure, the ECM determines that the EVAP system has a small leak, illuminates the MIL and stores the DTC (2 trip detection logic).

To reduce hydrocarbon emissions, evaporated fuel from the fuel tank is routed through a charcoal canister to the intake manifold for combustion in the cylinders.

The ECM changes the duty signals to the purge valve (Vacuum Switching Valve for Purge Control) so that the intake amount of hydrocarbon emissions is appropriate for the driving conditions (engine load, engine speed, vehicle speed, etc.) after the engine is warmed up.

The ECM monitors the output terminal voltage when the vacuum switching valve assembly is actuated. By turning the FET in the ECM on and off, the purge valve assembly is subject to duty control. If the ECM control value (drive signal) and the output terminal voltage duty cycle continue to not match, then the ECM interprets this as a malfunction in the vacuum switching valve circuit, illuminates the MIL, and stores the DTC.

The signal output from the sender gauge assembly installed in the fuel tank is converted to a CAN communication signal using the combination meter assembly, and this signal is input into the ECM as a remaining fuel signal.

The ECM uses the fuel sender gauge to monitor the amount of furl. There are several checks that the ECM performs to confirm the proper operation of the fuel sender gauge.

P0461

1. If the fuel sender gauge variation is lower than the estimated fuel consumption calculated from the fuel injection quantity and the engine speed, the ECM interprets this as a malfunction in the fuel sender gauge, and stores the DTC.

P0462, P0463

1. If an open or short in the fuel sender gauge signal line is detected, the ECM interprets this as a malfunction in the fuel sender gauge, and stores the DTC.

Vehicles, which are equipped with ABS (Anti-lock Brake System), detect the vehicle speed using the skid control ECU (brake actuator assembly) and wheel speed sensor. The wheel speed sensor monitors the wheel rotation speed and sends a signal to the skid control ECU. The skid control ECU converts the wheel speed signal into a 4-pulse signal and transmits it to the ECM. The ECM determines the vehicle speed based on the frequency of the pulse signal.

If the driving wheel speed signal input from the skid control computer indicates speed of 300 km/h (186.42 mph) or more, the ECM interprets this as a malfunction in the speed signal circuit. The ECM then illuminates the MIL and stores the DTC.

The idling speed is controlled by the ETCS (Electronic Throttle Control System). The ETCS is comprised of: 1) the one valve type throttle body; 2) the throttle actuator, which operates the throttle valve; 3) the throttle position sensor, which detects the opening angle of the throttle valve; 4) the accelerator pedal position sensor, which detects the accelerator pedal position; and 5) the ECM, which controls the ETCS. Based on the target idling speed, the ECM controls the throttle actuator to provide the proper throttle valve opening angle.

The ECM monitors the idling speed and idling air flow volume to conduct Idle Speed Control (ISC). The ECM determines that the ISC system is malfunctioning if the difference between the target engine idling speed and actual engine idling speed exceeds the threshold for 30 seconds or more.

The idling speed is controlled by the ETCS (Electronic Throttle Control System). The ETCS is comprised of: 1) the one valve type throttle body; 2) the throttle actuator, which operates the throttle valve; 3) the throttle position sensor, which detects the opening angle of the throttle valve; 4) the accelerator pedal position sensor, which detects the accelerator pedal position; and 5) the ECM, which controls the ETCS. Based on the target idling speed, the ECM controls the throttle actuator to provide the proper throttle valve opening angle.

The ECM monitors the idling speed and idling air flow volume to conduct Idle Speed Control (ISC). The ECM determines that the ISC system is malfunctioning if the difference between the target engine idling speed and actual engine idling speed exceeds the threshold for 30 seconds or more.

Cold start emission reduction strategy (CSERS) is employed to shorten the time to catalyst light-off from cold start. CSERS consists of retarded ignition timing and increased engine idle speed for a calibrated period of time. This monitor detects malfunctions of the ECM commanded ignition timing and engine idle speed not reaching the target values.

While the engine is being cranked, battery voltage is applied to terminal STA of the ECM. If the ECM detects the starter control (STA) signal after the engine is started, it determines that there is a malfunction in the STA circuit. The ECM then illuminates the MIL and stores the DTC.

The battery supplies electricity to the ECM even when the ignition switch is off. This power allows the ECM to store data such as DTC history, freeze frame data and fuel trim values. If the battery voltage falls below a minimum level, the memory is cleared and the ECM determines that there is a malfunction in the power supply circuit. When the engine is next started, the ECM illuminates the MIL and stores the DTC.

HINT

If DTC P0560 is stored, the ECM does not store other DTCs or the data stored in the ECM is partly cleared.

See also:
• ON-VEHICLE INSPECTION [07/2013 - ]
• ON-VEHICLE INSPECTION [07/2013 - ]
• ON-VEHICLE INSPECTION [07/2013 - ]
• ON-VEHICLE INSPECTION [07/2013 - ]
• ECM Power Source Circuit
• ON-VEHICLE INSPECTION [07/2013 - ] - Step 9
• REMOVAL [07/2013 - ]
• REMOVAL [07/2013 - ] - Step 1