Engine Control System (2GR-FE) (Diagnostic Codes (P0171 - P0606)) (Except Hybrid): Overview Toyota Highlander III

DESCRIPTION

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

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 lean.

Factors such as individual engine differences, wear over time and changes in operating environment cause short-term fuel trim to vary from the central value. The long-term fuel trim, which controls overall fuel compensation, compensates for long-term deviations in the fuel trim from the central value caused by the short-term fuel trim compensation.

HINT

1. When DTC P0171 or P0174 is stored, the actual air fuel ratio is on the lean side. When DTC P0172 or P0175 is stored, 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 stored. The MIL is then illuminated.
3. When the total of the short-term and long-term fuel trim values is within the malfunction threshold (and the engine coolant temperature is higher than 75°C [167°F]), the system is functioning normally.

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 fuel injection volumes estimated by the ECM also affect the average fuel trim learned value, which is a combination of the average short-term fuel trim (fuel feedback compensation value) and the average long-term fuel trim (learned value of the air fuel ratio). If the average fuel trim learned value exceeds the malfunction thresholds, the ECM interprets this as a fault in the fuel system and stores a DTC.

Example

The average fuel trim learned value is +35% (+48%)* or higher, or -35% or less, the ECM interprets this as a fuel system malfunction.

*: for Mexico models.

Scheme 361

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.

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 10 to 50 misfires per 1000 crankshaft revolutions) occurs once.
2. An excessive number of misfires (approximately 10 to 50 misfires per 1000 crankshaft revolutions) occurs a total of 4 times.

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

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.

Misfire Monitor for Mexico Models

1. 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 1000 misfires per 1000 crankshaft revolutions) occurs once.
2. An excessive number of misfires (approximately 500 misfires per 1000 crankshaft revolutions) occurs a total of 4 times.

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

1. A catalyst-damaging misfire, which is monitored every 200 crankshaft revolutions, occurs 3 times.

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

The knock control sensors are fitted onto the engine block to detect engine knocking.

The knock control 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, P0332 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.

Scheme 362

Reference: Inspection using an oscilloscope

HINT

The correct waveform is as shown.

If the output voltage transmitted by the knock control sensor remains low or high for 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.

The crankshaft position sensor system consists of a crank angle sensor plate (crankshaft) and a pickup coil. The crank angle sensor plate has 34 teeth at 10° intervals (2 teeth are missing for detecting top dead center), and is installed on the crankshaft.

The crankshaft position sensor generates 34 signals per crankshaft revolution. Based on these signals, the ECM calculates the crankshaft position and engine speed. Using these calculations, the fuel injection and ignition timing are controlled.

Scheme 363

1. Reference: Inspection using an oscilloscope HINT: The correct waveform is as shown. VV1+ and VV2+ stand for the VVT sensor (for intake camshaft) signal, and NE+ stands for the crankshaft position sensor signal. Grounding failure of the shielded wire may cause a noisy waveform. ECM Terminal Name Between NE+ and NE- Between VV1+ and VV1- Between VV2+ and VV1- Tester Range 5 V/DIV., 20 ms./DIV. Condition Idling

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

The VVT sensor (for intake camshaft) (VV1, VV2 signal) consists of a magnet and MRE (Magneto Resistance Element).

The camshaft timing gear assembly has a sensor plate for the VVT sensor. When the intake camshaft 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 intake camshaft rotation data to pulse signals, uses the pulse signals to determine the camshaft angle, and sends it to the ECM.

Then the ECM uses this data to control fuel injection duration, fuel injection timing and Variable Valve Timing (VVT) system.

HINT

Reference: Inspection using an oscilloscope.

Refer to DESCRIPTION

If no pulse signal is transmitted by the VVT sensor (for intake camshaft) despite the camshaft rotating, or if the rotation of the intake camshaft and the crankshaft is not synchronized, the ECM interprets this as a malfunction of the sensor.

Also, when the sensor output voltage remains at less than 0.3 V, or higher than 4.7 V for 4 seconds, the ECM stores a DTC.

HINT

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

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 assembly 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 the current supplied to the primary coil on and off. 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 (IGF1) signal to the ECM, for each cylinder ignition.

Scheme 364

Reference: Inspection using an oscilloscope

Scheme 365

HINT

While idling the engine, check the waveform between terminals IGT (1 to 6) and E1, and IGF1 and E1 of the ECM connector.

Scheme 366

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

The VVT sensor (for exhaust camshaft) (EV1, EV2 signal) consists of a magnet and MRE (Magneto Resistance Element).

The exhaust camshaft has a timing rotor for the VVT sensor. When the exhaust camshaft rotates, changes occur in the air gaps between the timing rotor and MRE, which affects the magnetic field. 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.

Then the ECM uses this data to control fuel injection duration, fuel injection timing and the Variable Valve Timing (VVT) system.

Scheme 367

1. Reference: Inspection using an oscilloscope HINT: The correct waveform is as shown. EV1+ and EV2+ stand for the VVT sensor (for exhaust camshaft) signal, and NE+ stands for the crankshaft position sensor signal. Grounding failure of the shielded wire may cause a noisy waveform. ECM Terminal Name Between NE+ and NE- Between EV1+ and VV1- Between EV2+ and VV1- Tester Range 5 V/DIV., 20 ms./DIV. Condition Idling

If no pulse signal is transmitted by the VVT sensor (for exhaust camshaft) despite the camshaft rotating, the ECM interprets this as a malfunction of the sensor.

Also, when the sensor output voltage remains at less than 0.3 V, or higher than 4.7 V for 4 seconds, the ECM stores 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 will illuminate the MIL and store a 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.

FOR MEXICO MODELS

Scheme 368

Note. If DTC P0420 is output, replace the exhaust manifold sub-assembly RH (*9) and the center exhaust pipe assembly (*8) together when catalyst replacement is necessary (Excluding air fuel ratio sensor*1 and heated oxygen sensor*3). If DTC P0430 is output, replace the exhaust manifold sub-assembly LH (*10) and the center exhaust pipe assembly (*8) together when catalyst replacement is necessary (Excluding air fuel ratio sensor*2 and heated oxygen sensor*4).

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

Refer to DESCRIPTION

5 hours* after the ignition 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 ignition 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 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 369

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) [726 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 370

The 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 ignition switch is turned off. The purge flow monitor runs while the engine is running.

Scheme 371

Scheme 372

Scheme 373

1. KEY-OFF MONITOR 5 hours* after the ignition 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 ignition 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 ignition 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 ignition 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. *1 Purge VSV: Off (Closed) *2 Purge VSV: On (Open) *3 Vent Valve: Off (Vent) *4 Vent Valve: On (Closed) *5 Leak Detection Pump: Off *6 Leak Detection Pump: On *7 Reference Orifice (0.02 inch) *8 Canister Pressure Sensor *9 Canister *10 Fuel Tank *11 Canister Pump Module *12 Canister Filter *a Operation A: Atmospheric Pressure Measurement *b Operation B, E: Reference Pressure Measurement *c Operation C: EVAP System Pressure Measurement *d Operation D: Purge VSV Monitor *e Atmospheric Pressure *f Negative Pressure 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. If any deterioration has occurred, the ECM will illuminate the MIL and store this 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 higher, 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 stores 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 0.15 kPa(gauge) [1.125 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 pressure, before and after conduction of the purge flow monitor, is measured by the ECM.

This DTC P0443 is applicable to Mexico models only.

To reduce hydrocarbon (HC) 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 VSV (Vacuum Switching Valve for Purge Control) so that the intake amount of hydrocarbon (HC) emissions is appropriate for the driving conditions (engine load, engine speed, vehicle speed, etc.) after the engine is warmed up.

Scheme 374

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON and turn the Techstream on.
3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
4. Turn the ignition switch off and wait for at least 30 seconds.
5. Turn the ignition switch to ON and turn the Techstream on.
6. Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [A]. HINT: The A/C switch and all accessory switches should be off.
7. Idle the engine for 15 minutes or more [B]. HINT: Check the EVAP (Purge) VSV item in the Data List. When the value of this item is between 5 and 95%, the judgment will be performed.
8. Enter the following menus: Powertrain / Engine / Trouble Codes [C].
9. Read the pending DTCs. HINT: If a pending DTC is output, the system is malfunctioning. If a pending DTC is not output, perform the following procedure.
10. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
11. Input the DTC: P0443.
12. Check the DTC judgment result. Techstream Display Description NORMAL DTC judgment completed System normal ABNORMAL DTC judgment completed System abnormal INCOMPLETE DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions N/A Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit HINT: If the judgment result shows NORMAL, the system is normal. If the judgment result shows ABNORMAL, the system has a malfunction. If the judgment result shows INCOMPLETE or N/A, perform steps [D] and [E].
13. Drive the vehicle at a constant speed between 40 and 60 km/h (25 and 37 mph) for 10 minutes [D]. WARNING: When performing the confirmation driving pattern, obey all speed limits and traffic laws.
14. Check the DTC judgment result again [E].

Scheme 375

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

Refer to DESCRIPTION

Scheme 376

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 this 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 this DTC. (Both 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: 42.11009 kPa(abs) [315.82568 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. If any deterioration has occurred, the ECM will illuminate the MIL and store this 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: 123.76147 kPa(abs) [928.21103 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. If any deterioration has occurred, the ECM will illuminate the MIL and store this DTC (1 trip detection logic).

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

Refer to DESCRIPTION

5 hours* 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 engine coolant temperature is not less than 35°C (95°F) 5 hours after the ignition 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 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 377

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).

Vehicles, which are equipped with ABS (Anti-lock Brake System), detect the vehicle speed using the skid control ECU (brake actuator assembly) and speed sensor. The 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 via the combination meter assembly. The ECM determines the vehicle speed based on the frequency of the pulse signal.

HINT

1. Various systems use the vehicle speed signal distributed from the combination meter assembly. Check all the components possibly related to the speed signal.
2. A voltage of 12 V or 5 V is output from each ECU and then input to the combination meter assembly. The signal is changed to a pulse signal at the transistor in the combination meter assembly. Each ECU controls its respective system based on this pulse signal.
3. If a short occurs in any of the ECUs or in the wire harness connected to an ECU, all systems using the speed signal will not operate normally.

Scheme 378

If there is no speed signal from the combination meter assembly even though the ECM determines that the vehicle is being driven, the ECM interprets this as a malfunction in the speed signal circuit. The ECM then illuminates the MIL and stores this DTC.

The stop light switch assembly is a duplex system that transmits two signals: STP and ST1-. These two signals are used by the ECM to monitor whether or not the brake system is working properly. If the signals, which indicate the brake pedal is being depressed and released, are detected simultaneously, the ECM interprets this as a malfunction in the stop light switch assembly and stores the DTC.

HINT

The normal signal conditions are as shown in the table below.

1. [OFF] denotes ground potential.
2. [ON] denotes battery potential (+B).
3. On the Techstream, both the Data List items Stop Light Switch and ST1 are ON when the brake pedal is depressed because the ST1 indication characteristic is opposite to the Stop Light Switch indication.

Scheme 379

Scheme 380

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 idle speed and idling air flow volume to conduct idle speed control. The ECM determines that the idle speed control system is malfunctioning if either of the following conditions is met

1. The difference between the target engine idle speed and actual engine idle 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 idle 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 381

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 will be stored after the engine idles for 13 seconds (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 less than 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 electronic 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. The idle speed control learned values are cleared by performing a learned value reset. Idle speed control learning needs to be performed before this DTC can be stored.

HINT

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

Scheme 382

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 (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 less than 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 stored when the malfunction is detected in consecutive driving cycles (2 trip detection logic).

Note. The idle speed control learned values are cleared by performing a learned value reset. Idle speed control learning needs to be performed before this DTC can be stored.

HINT

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

Scheme 383

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 will illuminate the MIL and store this DTC.

HINT

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

The ECM continuously monitors its internal memory status. This self-check ensures that the ECM is functioning properly. The ECM memory status is diagnosed by internal mirroring of the main CPU and sub CPU to detect Random Access Memory (RAM) errors. If outputs from these CPUs are different and deviate from the standard, the ECM will illuminate the MIL and store this DTC.

The ECM continuously monitors its main and sub CPUs. This self-check ensures that the ECM is functioning properly. If outputs from these CPUs are different and deviate from the standard, the ECM will illuminate the MIL and store this DTC.

See also:
• ON-VEHICLE INSPECTION [12/2013 - ]
• PROCEDURE - Step 2
• PROCEDURE - Step 1
• REMOVAL [12/2013 - ]
• PROCEDURE - Step 10
• REASSEMBLY [12/2013 - ]
• COMPONENTS [12/2013 - ]