Engine Control System (Diagnostic Codes (P014C - P0560)): Overview Lexus GS IV

DESCRIPTION

HINT

Refer to DTC P2195. Refer to DESCRIPTION .

*: Calculated by ECM based on the air fuel ratio sensor output.

MONITOR DESCRIPTION

After the engine is warmed up, the ECM carries out air-fuel ratio feedback control, and maintains the air-fuel ratio at the theoretical level. In addition, after all the preconditions have been met, active air-fuel ratio control is carried out for approx. 10 seconds and during active air-fuel ratio control, the ECM measures the response of the air-fuel ratio sensor by increasing or decreasing a specific injection quantity based on the theoretical air-fuel ratio learned during normal air-fuel control. The ECM determines whether there is an air-fuel ratio sensor malfunction at the mid-point of active air-fuel ratio control.

If the air-fuel ratio sensor's response ability is reduced, DTCs P014C, P014D, P014E and P014F are output.

If the time it takes the air-fuel ratio sensor output to change is delayed, DTCs P015A, P015B, P015C and P015D are output.

Scheme 132

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 or P0174 is set, the actual air-fuel ratio is on the lean side. When DTC P0172 or P0175 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 or P0174 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.

1. Example: If the average fuel trim learning value is 35% or more or -35% or less, the ECM interprets this as a fuel system malfunction.

Scheme 133

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 between 2 and 18 MPa (20.4 and 183.5 kgf/cm 2 , 290 and 2609 psi). 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.

Scheme 134

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 power switch is turned off.

The D-4S system has two fuel injection methods. One is the in-cylinder direct injection method that directly injects pressurized fuel into the combustion chamber. The other is the intake port injection method. The ECM determines which fuel injection method to use in accordance with the engine conditions. For the in-cylinder direction injection method, the injector driver (EDU) in the engine room operates the fuel injectors (for direction injection) at high speeds. The EDU receives fuel injection request signals from the ECM and converts the signals to high voltage / high current injector operation signals to operate the fuel injectors (for direction injection).

The fuel injection sequence occurs in numerical order from No. 1 to No. 6.

The ECM monitors the EDU at all times. If drivers or fuel injectors are malfunctioning, the EDU sends fuel injector operation condition signals (fail signals INJ1 to INJ3) to the ECM. When the ECM receives the signals, the ECM stops the fuel injection control of the appropriate cylinders and illuminates the MIL.

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high hydrocarbons concentration levels can cause an increase in exhaust emission levels. 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 camshaft position sensor and the crankshaft position sensor. The camshaft position 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 exceeds the threshold levels and may cause emission deterioration, the ECM illuminates the MIL and sets a DTC.

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

The ECM illuminates the MIL and sets 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 of the engine starting, an excessive misfiring rate (approximately 10 to 50 misfires per 1000 crankshaft revolutions) occurs once.
2. After the first 1000 crankshaft revolutions, an excessive misfiring rate (approximately 10 to 60 misfires per 1000 crankshaft revolutions) occurs 4 times in sequential crankshaft revolutions.

The ECM flashes the MIL (immediate detection logic) and sets a DTC (2 trip detection logic) when either one of the following conditions, which could cause the Three-Way Catalytic Converter (TWC) damage, is detected

1. In every 200 crankshaft revolutions at a high engine speed, the threshold misfiring percentage is recorded once.
2. In every 200 crankshaft revolutions at a normal engine speed, the threshold misfiring percentage is recorded 3 times.

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

Knock sensors are 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 any of DTCs P0327, P0328, P0332 and P0333 are set, 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 power switch is turned off.

Reference: Inspection using an oscilloscope

Scheme 135

The correct waveform is as shown in the illustration.

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

The monitor for DTCs P0327, P0328, P0332 and P0333 begins to run when 5 seconds have elapsed since the engine was started.

If the malfunction is not repaired successfully, DTC P0327, P0328, P0332 or P0333 is stored 5 seconds after the engine is next started.

The crankshaft position sensor system consists of a crank angle sensor plate and a pickup coil. The sensor plate has 34 teeth and is installed on the crankshaft. The pickup coil is made of wound copper wire, an iron core and magnet.

The sensor plate rotates and, as each tooth passes by the pickup coil, a pulse signal is created. The pickup coil generates 34 signals per engine rotation. Based on these signals, the ECM calculates the crankshaft position and engine speed. Using these calculations, the fuel injection timing and ignition timing are controlled.

Scheme 136

1. Reference: Inspection using an oscilloscope HINT: The correct waveform is as shown. VV1+ and VV2+ stand for the VVT sensor signal, and NE+ stands for the crankshaft position sensor signal. Item Content ECM Terminal Names Between VV1+ and VV1-, VV2+ and VV2- Between NE+ and NE- Tester Range 5 V/DIV. 20 ms./DIV. Condition Idling

If there is no signal from the crankshaft position sensor despite the engine running, the ECM interprets this as a malfunction of the sensor.

If the malfunction is not repaired successfully, a DTC is set 10 seconds after the engine is next started.

The intake camshaft VVT sensors (VV1, VV2 signal) 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 plate has 34 teeth. The pickup coil generates 34 signals for each engine rotation. 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.

1. Reference: Inspection using an oscilloscope HINT: The correct waveform is as shown. VV1+ and VV2+ stand for the VVT sensor signal, and NE+ stands for the crankshaft position sensor signal. Item Content ECM Terminal Names Between VV1+ and VV1-, VV2+ and VV2- Between NE+ and NE- Tester Range 5 V/DIV. 20 ms./DIV. Condition Idling

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.

HINT

1. These DTCs indicate malfunctions relating to the primary circuit.
2. If DTC P0351 is set, check the No. 1 ignition coil assembly circuit.
3. If DTC P0352 is set, check the No. 2 ignition coil assembly circuit.
4. If DTC P0353 is set, check the No. 3 ignition coil assembly circuit.
5. If DTC P0354 is set, check the No. 4 ignition coil assembly circuit.
6. If DTC P0355 is set, check the No. 5 ignition coil assembly circuit.
7. If DTC P0356 is set, check the No. 6 ignition coil assembly circuit.

A direct ignition system is used on this vehicle.

The direct ignition system is a 1-cylinder ignition system in which each cylinder is ignited by one ignition coil assembly and a 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. Spark of the spark plugs passes from the center electrode to the ground electrodes.

The ECM determines the ignition timing and transmits the ignition signals (IGT) 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. As the ECM cuts the current to the primary coil, the igniter sends back an ignition confirmation signal (IGF) to the ECM, for each cylinder ignition.

Scheme 137

Scheme 138

1. Reference: Inspection using an oscilloscope
2. While cranking or idling the engine, check the waveform between terminals IGT (1 to 6) and E1, and IGF (1 or 2) and E1 of the ECM connectors. HINT: The wavelength becomes shorter as the engine speed increases. Item Content ECM Terminal Names CH1: Between IGT (1 to 6) and E1 CH2: Between IGF (1 or 2) and E1 Tester Range 2 V/DIV. 20 ms./DIV. Condition Idling

Scheme 139

If the ECM does not receive any IGF signals despite the IGT signal being transmitted, it interprets this as a fault in the igniter and sets a DTC.

If the malfunction is not repaired successfully, a DTC is set 1 second after the engine is next started.

The exhaust camshaft VVT sensors (EV1, EV2) consist of a magnet and MRE (Magnetic Resistive Element).

The exhaust camshaft has a sensor plate with 3 teeth on its outer circumference.

When the exhaust camshaft rotates, changes occur in the air gaps between the 3 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 plate has 34 teeth. The pickup coil generates 34 signals for each engine rotation. 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.

Reference: Inspection using an oscilloscope

Scheme 140

HINT

1. The correct waveform is as shown in the illustration.
2. The wavelength becomes shorter as the engine speed increases.
3. EV1+ and EV2+ stand for the VVT sensor for exhaust side signal, and NE+ stands for the crankshaft position sensor signal. Item Content ECM Terminal Names Between EV1+ and EV1-, or EV2+ and EV2- Between NE+ and NE- Tester Range 5 V/DIV., 20 ms./DIV. Condition Idling

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.

When the sensor output voltage remains less than 0.3 V, or more than 4.7 V for more than 5 seconds, the ECM 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 while performing active air fuel ratio control.

The oxygen storage capacity value is an indication of the oxygen storage capacity of the three-way catalytic converter. When the vehicle is being driven with a warm engine, active air fuel ratio control is performed for approximately 15 to 20 seconds. When it is performed, the ECM deliberately sets the air fuel ratio to lean or rich levels. If the cycle of the waveform for the heated oxygen sensor is long, the oxygen storage capacity is great. There is a direct correlation between the heated oxygen sensor and the oxygen storage capacity of the three-way catalytic converter.

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 sets 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 141

TEXT IN ILLUSTRATION

Note. When DTC P0420 is output, replace the exhaust manifold sub-assembly RH (*1) and the front exhaust pipe assembly (*7) together when catalyst replacement is necessary. (Excluding air fuel ratio sensor *3 and heated oxygen sensor *5) When DTC P0430 is output, replace the exhaust manifold sub-assembly LH (*2) and the front exhaust pipe assembly (*7) together when catalyst replacement is necessary. (Excluding air fuel ratio sensor *4 and heated oxygen sensor *6)

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

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

HINT

*: If the engine coolant temperature is not less than 35°C (95°F) 5 hours after the power switch is turned off, the monitor check starts 2 hours later. If it is still not less than 35°C (95°F) 7 hours after the power 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 142

TEXT IN ILLUSTRATION

The leak detection pump creates negative pressure through the reference orifice (in operation B and E). When the system is normal, the EVAP pressure is between 97 to 100 kPa(abs) [728 to 750 mmHg(abs)]* and saturated within a minute. If not, the ECM interprets this as a malfunction. The ECM illuminates the MIL and stores a DTC if this malfunction is detected in consecutive drive cycles.

*: Typical value.

Scheme 143

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

The 2 monitors, key-off and purge flow, are used to detect malfunctions relating to DTC P0441. The key-off monitor is initiated by the ECM internal timer, known as the soak timer, 5 hours* after the power switch is turned off. The purge flow monitor runs while the engine is running.

Scheme 144

Scheme 145

Scheme 146

Scheme 147

1. KEY-OFF MONITOR 5 hours* after the power switch is turned off, the electric 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 engine coolant temperature is not less than 35°C (95°F) 5 hours after the power switch is turned off, the monitor check starts 2 hours later. If it is still not less than 35°C (95°F) 7 hours after the power switch is turned off, the monitor check starts 2.5 hours later. Sequence Operation Description Duration - ECM activation Activated by soak timer 5, 7 or 9.5 hours after power switch turned off. - A Atmospheric pressure measurement Vent valve is turned off (vent) and EVAP system pressure is measured by ECM in order to register atmospheric pressure. If pressure in EVAP system is not between 70 kPa(abs) and 110 kPa(abs) [525 mmHg(abs) and 825 mmHg(abs)], ECM cancels EVAP system monitor. 60 seconds B First reference pressure measurement In order to determine reference pressure, leak detection pump creates negative pressure (vacuum) through reference orifice and then ECM checks if leak detection pump and vent valve operate normally. 360 seconds C EVAP system pressure measurement Vent valve is turned on (closed) to shut EVAP system. Negative pressure (vacuum) is created in EVAP system, and EVAP system pressure is then measured. Write down measured value as it will be used in leak check. If EVAP pressure does not stabilize within 15 minutes, ECM cancels EVAP system monitor. 15 minutes* D Purge VSV monitor Purge VSV opened and then EVAP system pressure is measured by ECM. A large increase indicates normality. 10 seconds E Second reference pressure measurement After second reference pressure measurement, leak check is performed by comparing first and second reference pressure measurements. If stabilized system pressure is higher than second reference pressure, ECM determines that EVAP system leaking. 60 seconds - Final check Atmospheric pressure is measured and then monitoring result is recorded by ECM. - *: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize. TEXT IN ILLUSTRATION *1 Operation A: Atmospheric Pressure Measurement *2 Operation B, E: *3 Purge VSV: OFF *4 Canister *5 Reference Orifice *6 Fuel Tank *7 Vent Valve: OFF (vent) *8 Canister Pump Module *9 Canister Pressure Sensor *10 Canister Filter *11 Leak Detection Pump: OFF *12 OFF *13 OFF (vent) *14 Reference Leak Pressure Measurement *15 ON *16 Reference Orifice (0.02 inch) *17 Operation C: EVAP System Pressure Measurement *18 ON (closed) *19 Atmospheric Pressure *20 Negative Pressure *21 OFF *22 ON *23 Operation D: Purge VSV Monitor *24 ON *25 ON (closed) *26 ON Purge VSV stuck open In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) system. The EVAP system pressure is then measured by the ECM using the canister pressure sensor. If the stabilized system pressure is higher than [second reference pressure x 0.2], the ECM interprets this as the purge VSV being stuck open. The ECM illuminates the MIL and stores the DTC (2 trip detection logic). Purge VSV stuck closed In operation D, the canister pressure sensor measures the EVAP (Evaporative Emission) system pressure. The pressure measurement for the purge VSV monitor begins when the purge VSV is turned on (open) after the EVAP leak check. When the measured pressure indicates an increase of 0.3 kPa(gauge) [2.25 mmHg(gauge)] or more, the purge VSV is functioning normally. If the pressure does not increase, the ECM interprets this as the purge VSV being stuck closed, illuminates the MIL and sets the DTC (2 trip detection logic).
2. PURGE FLOW MONITOR 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 VSV is on (open), the ECM monitors the purge flow by measuring the EVAP pressure change. If negative pressure is not created, 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 less than 0.5 kPa(gauge) [3.751 mmHg(gauge)], the ECM interprets this as the purge VSV being stuck closed, illuminates the MIL and stores DTC P0441 (2 trip detection logic).

Atmospheric pressure check

In order to ensure reliable malfunction detection, the variation between the atmospheric pressures, before and after conduction of the purge flow monitor, is measured by the ECM.

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

Scheme 148

1. DTC P0451: Canister pressure sensor abnormal voltage fluctuation or being constant If the canister pressure sensor voltage output fluctuates rapidly for 10 seconds, the ECM stops the EVAP system monitor. The ECM interprets this as the canister pressure sensor voltage fluctuating, and stops the EVAP system monitor. The ECM then illuminates the MIL and stores the DTC. Alternatively, if the sensor voltage output does not change for 2 minutes, the ECM interprets this as the sensor being stuck, and stops the monitor. The ECM then illuminates the MIL and stores the DTC. (Both the malfunctions are detected by 2 trip detection logic.)
2. DTC P0452: Canister pressure sensor voltage low If the canister pressure sensor voltage output (pressure) is less than 0.45 V: 42.11 kPa(abs) [315.83 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 higher than 4.9 V: 123.761 kPa(abs) [928.208 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).

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

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

HINT

*: If the engine coolant temperature is not less than 35°C (95°F) 5 hours after the power switch is turned off, the monitor check starts 2 hours later. If it is still not less than 35°C (95°F) 7 hours after the power 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 149

TEXT IN ILLUSTRATION

Scheme 150

1. (a) P0455: EVAP (Evaporative Emission) gross leak In operation C, 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 0.2] (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 C, 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).

The idle speed is controlled by the electronic throttle control system. The electronic throttle control system is comprised of: 1) one valve type throttle body with motor assembly; 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; 5) the ECM, which controls the electronic throttle control system. Based on the target idle 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 either of the following conditions is met

1. The difference between the target engine idling speed and actual engine idling speed exceeds the threshold and the IAC flow rate learned value is stuck at the upper or lower limit for 5 seconds or more.
2. After driving at a vehicle speed of 10 km/h (6.25 mph) or more, the difference between the target and actual engine idling speed exceeds the threshold 5 times or more during a driving cycle, and then the system determines that the IAC flow rate learned value is stuck at the upper or lower limit, or that the IAC flow rate learned value has been changed by an amount that exceeds the threshold.

Scheme 151

This monitor will run when the engine is started at an engine coolant temperature of -10 to 50°C (14 to 122°F). The DTC is stored after the engine idles for 13 seconds or more (2 trip detection logic).

The DTC is designed to monitor the idle air control at cold start. When the engine is started at an engine coolant temperature of below 50°C (122°F), the ECM measures the accumulated mass air flow during engine idling. If the accumulated mass air flow does not reach the specified level within 10 seconds, the ECM interprets this as a malfunction. The MIL is illuminated and a DTC is stored when the malfunction is detected in consecutive driving cycles (2 trip detection logic).

The electronic throttle control system controls the idle speed. The electrical throttle control system operates the throttle actuator to open and close the throttle valve, and adjusts the intake air amount to achieve the target idle speed.

Note. When the negative (-) auxiliary battery terminal is disconnected during inspection or repairs, the idle speed control learned values are cleared. Idle speed control learning is performed when the engine has been warmed up and idled for 5 minutes because this DTC cannot be set after the idle speed control learned values are cleared.

HINT

Idle speed control learning is performed when the engine is warmed up and has been idling 5 minutes.

Scheme 152

This monitor will run when the engine is started at an engine coolant temperature of -10 to 50°C (14 to 122°F). The DTC is stored after the engine idles for 13 seconds or more (2 trip detection logic).

The DTC is designed to monitor the ignition timing at cold start. When the engine is started at an engine coolant temperature of below 50°C (122°F), the ECM checks the ignition timing during engine idling. If the ignition timing advances beyond the specified level within 10 seconds, the ECM interprets this as a malfunction. The MIL is illuminated and a DTC is set when the malfunction is detected in consecutive driving cycles (2 trip detection logic).

The electronic throttle control system controls the idle speed. The electrical throttle control system operates the throttle actuator to open and close the throttle valve, and adjusts the intake air amount to achieve the target idle speed.

Note. When the negative (-) auxiliary battery terminal is disconnected during inspection or repairs, the idle speed control learned values are cleared. Idle speed control learning is performed when the engine has been warmed up and idled for 5 minutes because this DTC cannot be set after the idle speed control learned values are cleared.

HINT

Idle speed control learning is performed when the engine is warmed up and has been idling 5 minutes.

Scheme 153

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

HINT

If DTC P0560 is set, the ECM does not store other DTCs.

See also:
• ON-VEHICLE INSPECTION [03/2012 - ] - Step 2
• ON-VEHICLE INSPECTION [03/2012 - ]
• ON-VEHICLE INSPECTION [03/2012 - ] - Step 2
• ON-VEHICLE INSPECTION [03/2012 - ] - Step 3
• REMOVAL [03/2012 - ]