Engine Control (Diagnostic Codes (P043E-U0293) & Circuit Tests): Overview Lexus HS I

DESCRIPTION

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

HINT

Unit expression

1. (kPa-a [mmHg-a]) denotes absolute pressure.
2. (kPa-g [mmHg-g]) denotes gauge pressure (relative pressure).
3. On the Techstream, convert the unit of measurement according to the inspection procedure.

MONITOR DESCRIPTION

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

HINT

*1: If the engine coolant temperature is not below 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 below 35°C (95°F) 7 hours after the power switch is turned off, the monitor check starts 2.5 hours later.

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

Scheme 26

Scheme 27

The leak detection pump creates negative pressure through the reference orifice. When the system is normal, the EVAP pressure is in 97 to 100 kPa-a (728 to 750 mmHg-a)* and saturated within a minute.

If not, the hybrid vehicle control ECU interprets this as a malfunction. The hybrid vehicle control ECU will illuminate the MIL and set DTC if this malfunction is detected in consecutive driving cycle.

*: Typical valve

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

HINT

Unit expression

1. (kPa-a [mmHg-a]) denotes absolute pressure.
2. (kPa-g [mmHg-g]) denotes gauge pressure (relative pressure).
3. On the Techstream, convert the unit of measurement according to the inspection procedure.

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 hybrid vehicle control ECU internal timer, known as the soak timer, 5 hours*1 after the power switch is turned off. The purge flow monitor runs while the engine is running.

Scheme 28

Scheme 29

Scheme 30

Scheme 31

1. KEY-OFF MONITOR 5 hours*1 after the power switch is turned off, the electric leak detection pump creates negative pressure (vacuum) in the EVAP (Evaporative Emission) system. The hybrid vehicle control ECU monitors for leaks and actuator malfunctions based on the EVAP pressure. HINT: *1: If the engine coolant temperature is not below 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 below 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 - Hybrid vehicle control ECU 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 hybrid vehicle control ECU in order to register atmospheric pressure. If pressure in EVAP system is not between 70 kPa-a and 110 kPa-a (525 mmHg-a and 825 mmHg-a), hybrid vehicle control ECU cancels EVAP system monitor. 60 seconds B First 0.02 inch leak pressure measurement In order to determine 0.02 inch leak pressure standard, leak detection pump creates negative pressure (vacuum) through 0.02 inch orifice and then hybrid vehicle control ECU 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, hybrid vehicle control ECU cancels EVAP system monitor. 15 minutes*2 D Purge VSV monitor Purge VSV is opened and then EVAP system pressure is measured by hybrid vehicle control ECU. A large increase indicates normal. 10 seconds E Second 0.02 inch leak pressure measurement After a second 0.02 inch leak pressure measurement, leak check is performed by comparing first and second 0.02 inch leak pressure standards. If stabilized system pressure is higher than second 0.02 inch leak pressure standard, hybrid vehicle control ECU determines that EVAP system leaking. 60 seconds F Final check Atmospheric pressure is measured and then monitor result is recorded by hybrid vehicle control ECU. - *2: If only a small amount of fuel is in the fuel tank, it takes longer for the EVAP pressure to stabilize. 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 hybrid vehicle control ECU using the canister pressure sensor. If the stabilized system pressure is higher than [second 0.02 inch leak pressure standard x 0.2], the hybrid vehicle control ECU interprets this as the purge VSV being stuck open. The hybrid vehicle control ECU illuminates the MIL and sets the DTC (2 trip detection logic). HINT: *: DTC P0441 may be stored if the hose between the purge VSV and canister is disconnected during evaporative emission control system. Purge VSV stuck closed In operation D, the canister pressure sensor measures the EVAP (Evaporative Emission) system pressure. The pressure measurement for 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-g (2.25 mmHg-g) or more, the purge VSV is functioning normally. If the pressure does not increase, the hybrid vehicle control ECU interprets this as the purge VSV being stuck closed. The hybrid vehicle control ECU illuminates the MIL and sets the DTC (2 trip detection logic).
2. PURGE FLOW MONITOR The purge flow monitor consists of the 2 step monitors. The 1st monitor is conducted every time and the 2nd monitor is activated if necessary. The 1st monitor While the engine is running and the purge VSV is on (open), the hybrid vehicle control ECU monitors the purge flow by measuring the EVAP pressure change. If negative pressure is not created, the hybrid vehicle control ECU begins the 2nd monitor. 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-g (3.75 mmHg-g), the hybrid vehicle control ECU interprets this as the purge VSV being stuck closed, and illuminates the MIL and sets 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 hybrid vehicle control ECU.

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

HINT

Unit expression

1. (kPa-a [mmHg-a]) denotes absolute pressure.
2. (kPa-g [mmHg-g]) denotes gauge pressure (relative pressure).
3. On the Techstream, convert the unit of measurement according to the inspection procedure.

Scheme 32

1. DTC P0451: Canister pressure sensor abnormal voltage fluctuation If the canister pressure sensor voltage output fluctuates rapidly for 10 seconds, the hybrid vehicle control ECU stops the EVAP system monitor. The hybrid vehicle control ECU interprets this as the canister pressure sensor voltage fluctuating, and stops the EVAP system monitor. The hybrid vehicle control ECU then illuminates the MIL and sets the DTC. (Malfunction is detected by 2 trip detection logic.)
2. DTC P0452: Canister pressure sensor voltage low If the canister pressure sensor voltage output (pressure) is below 0.45 V (42.11 kPa-a (316 mmHg-a)), the hybrid vehicle control ECU interprets this as an open or short circuit in the canister pressure sensor or its circuit, and stops the EVAP system monitor. The hybrid vehicle control ECU then illuminates the MIL and sets the DTC (1 trip detection logic).
3. DTC P0453: Canister pressure sensor voltage high If the canister pressure sensor voltage output (pressure) is 4.9 V (123.761 kPa-a (928.5 mmHg-a) or more, the hybrid vehicle control ECU interprets this as an open or short circuit in the canister pressure sensor or its circuit, and stops the EVAP system monitor. The hybrid vehicle control ECU then illuminates the MIL and sets the DTC (1 trip detection logic).

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

HINT

Unit expression

1. (kPa-a [mmHg-a]) denotes the absolute pressure.
2. (kPa-g [mmHg-g]) denotes the gauge pressure (relative pressure).
3. On the Techstream, convert the unit of measurement according to the inspection procedure.

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

HINT

*1: If the engine coolant temperature is not below 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 below 35°C (95°F) 7 hours after the power switch is turned off, the monitor check starts 2.5 hours later.

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

Scheme 33

1. 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 0.02 inch leak pressure standard x 0.2] (near atmospheric pressure), the hybrid vehicle control ECU determines that the EVAP system has a large leak, illuminates the MIL and sets the DTC (2 trip detection logic).
2. 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 0.02 inch leak pressure standard, the hybrid vehicle control ECU determines that the EVAP system has a small leak, illuminates the MIL and sets 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 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; and 5) the hybrid vehicle control ECU, which controls the electronic throttle control system. Based on the target idle speed, the hybrid vehicle control ECU controls the throttle actuator to provide the proper throttle valve opening angle.

The hybrid vehicle control ECU monitors the idle speed and idle air flow volume to conduct Idle Speed Control (ISC). The hybrid vehicle control ECU determines that the idle speed control system is malfunctioning if the following conditions are met

Scheme 34

1. The learned idle air flow volume remains at the maximum or minimum volume for 5 seconds or more during a driving cycle.
2. After driving at a vehicle speed of 6.25 mph (10 km/h) or more, the actual engine idle speed varies from the target idle speed by less than -100 rpm or 150 rpm or more, 5 times or more during a driving cycle, the hybrid vehicle control ECU illuminates the MIL and sets the DTC.

This monitor will run when the engine is started at -10 to 50°C (14 to 122°F) of the engine coolant temperature. The DTC can be set after the engine idling 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 lower than 50°C (122°F) of the engine coolant temperature, the hybrid vehicle control ECU measures the accumulated mass air flow at idle. If it does not reach the criteria within 10 seconds, the hybrid vehicle control ECU 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 battery terminal is disconnected during inspection or repairs, the idle speed control (ISC) learned values are cleared. Idle speed control learning needs to be performed before this DTC can be stored. To perform idle speed control learning, the engine must be warmed up by allowing it to idle for 5 minutes. For idle speed control learning to be successful, when the engine is started to warm it up, there must be at least 10 seconds of idling with the coolant temperature below 50°C (122°F) before allowing it to continue running for the 5 minute learning period.

HINT

The idle speed control leaning is performed when the engine is warmed up and has been idling for 5 minutes.

Scheme 35

This monitor will run when the engine is started at -10 to 50°C (14 to 122°F) of the engine coolant temperature. The DTC can be set 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 lower than 50°C (122°F) of the engine coolant temperature, the hybrid vehicle control ECU measures the accumulated mass air flow at idle. If it does not reach the criteria within 10 seconds, the hybrid vehicle control ECU 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 (-) 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.

Scheme 36

The battery supplies electricity to the hybrid vehicle control ECU even when the power switch is off. This power allows the hybrid vehicle control ECU 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 hybrid vehicle control ECU determines that there is a malfunction in the power supply circuit. The next time the engine is started, the hybrid vehicle control ECU illuminates the MIL and sets the DTC.

HINT

If DTC P0560 is set, the hybrid vehicle control ECU does not store other DTCs or the data stored in the hybrid vehicle control ECU may be partly cleared.

The hybrid vehicle control ECU continuously monitors its internal memory status. This self-check ensures that the hybrid vehicle control ECU is functioning properly. It 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 standards, the hybrid vehicle control ECU will illuminate the MIL and set the DTC immediately.

The hybrid vehicle control ECU continuously monitors its main and sub CPUs. This self-check ensures that the hybrid vehicle control ECU is functioning properly. If outputs from the CPUs are different and deviate from the standards, the hybrid vehicle control ECU will illuminate the MIL and set the DTC immediately.

The hybrid vehicle control ECU continuously monitors its internal processors (CPUs) and heated oxygen sensor transistors. This self-check ensures that the hybrid vehicle control ECU is functioning properly.

The main CPU and sub CPU of the hybrid vehicle control ECU communicate with each other. The main CPU monitors the communications and WDC pulses from the sub CPU. When the signal malfunctions below deviate, the DTC is stored.

The hybrid vehicle control ECU monitors the input signals of the No. 1 throttle position sensor. When the hybrid vehicle control ECU monitors the input signal of the No. 1 throttle position sensor, if the input signal and control signal deviate, the DTC is stored.

The hybrid vehicle control ECU monitors the output voltage to the throttle actuator. This self-check ensures that the hybrid vehicle control ECU is functioning properly. The output voltage is usually 0 V when the power switch is turned off. If the output voltage is higher than 7 V when the power switch is turned off, the hybrid vehicle control ECU will illuminate the MIL and set the DTC the next time the power switch is turned on (IG).

HINT

*: Data List Name

This DTC is designed to detect a deviation in the output characteristics of a pressure sensor.

The pressure of the canister pressure sensor and manifold absolute pressure sensor is monitored 55 minutes after the power switch is turned off. If there is a difference in the pressures, the MIL is illuminated (2 trip detection logic).

HINT

Correct judgment may not be possible when the altitude is 13124 ft. (4000 m) or more.

The throttle actuator is operated by the hybrid vehicle control ECU and opens and closes the throttle valve using gears.

The opening angle of the throttle valve is detected by the throttle position sensor, which is mounted on the throttle body assembly. The throttle position sensor provides feedback to the hybrid vehicle control ECU. This feedback allows the hybrid vehicle control ECU to appropriately control the throttle actuator and monitor the throttle opening angle as the hybrid vehicle control ECU responds to driver inputs.

HINT

This electronic throttle control system does not use a throttle cable.

The hybrid vehicle control ECU monitors the electrical current through the electronic actuator, and detects malfunctions and open circuits in the throttle actuator based on this value. If the current is outside the standard range, the hybrid vehicle control ECU determines that there is a malfunction in the throttle actuator. In addition, if the throttle valve does not function properly (for example, stuck on), the hybrid vehicle control ECU determines that there is a malfunction. The hybrid vehicle control ECU then illuminates the MIL and stores a DTC.

Example

1. When the electrical current is below 0.5 A and the throttle actuator duty ratio exceeds 80%, the hybrid vehicle control ECU interprets this as the current being outside the standard range, illuminates the MIL and stores a DTC.

The throttle actuator is operated by the hybrid vehicle control ECU, and opens and closes the throttle valve using gears. The opening angle of the throttle valve is detected by the throttle position sensor, which is mounted on the throttle body assembly. The throttle position sensor provides feedback to the hybrid vehicle control ECU. This feedback allows the hybrid vehicle control ECU to appropriately control the throttle actuator and monitor the throttle opening angle as the hybrid vehicle control ECU responds to driver inputs.

HINT

This electronic throttle control system does not use a throttle cable.

The hybrid vehicle control ECU determines that there is a malfunction in the electronic throttle control system when the throttle valve remains at the fixed angle despite a high drive current from the hybrid vehicle control ECU. The hybrid vehicle control ECU illuminates the MIL and stores a DTC.

If the malfunction is not repaired successfully, a DTC is stored when the accelerator pedal is fully depressed and released quickly (to fully open and close the throttle valve) after the engine is next started.

The electronic throttle control system has a dedicated power supply circuit. The voltage (+BM) is monitored and when it is low (below 4 V), the hybrid vehicle control ECU determines that there is a malfunction in the electronic throttle control system and cuts off the current to the throttle actuator.

When the voltage becomes unstable, the electronic throttle control system itself becomes unstable. For this reason, when the voltage is low, the current to the throttle actuator is cut. If repairs are made and the system returns to normal, turn the power switch off. The hybrid vehicle control ECU then allows the current to flow to the throttle actuator so that it can be restarted.

HINT

This electronic throttle control system does not use a throttle cable.

Scheme 37

The hybrid vehicle control ECU monitors the battery supply voltage applied to the throttle actuator.

When the power supply voltage (+BM) drops below 4 V for 0.8 seconds or more, the hybrid vehicle control ECU interprets this as an open in the power supply circuit (+BM). The hybrid vehicle control ECU illuminates the MIL and stores the DTC.

If the malfunction is not repaired successfully, the DTC is stored 5 seconds after the engine is next started.

The electronic throttle control system is composed of the throttle actuator, throttle position sensor, accelerator pedal position sensor, and hybrid vehicle control ECU. The hybrid vehicle control ECU operates the throttle actuator to regulate the throttle valve in response to driver inputs. The throttle position sensor detects the opening angle of the throttle valve, and provides the hybrid vehicle control ECU with feedback so that the throttle valve can be appropriately controlled by the hybrid vehicle control ECU.

The hybrid vehicle control ECU determines the actual opening angle of the throttle valve from the throttle position sensor signal. The actual opening angle is compared to the target opening angle commanded by the hybrid vehicle control ECU. If the difference between these 2 values is outside the standard range, the hybrid vehicle control ECU interprets this as a malfunction in the electronic throttle control system. The hybrid vehicle control ECU then illuminates the MIL and stores the DTC.

If the malfunction is not repaired successfully, the DTC is stored when the accelerator pedal is quickly released (to close the throttle valve) after the engine speed reaches 5000 rpm by depressing the accelerator pedal (fully open the throttle valve).

HINT

1. Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor.
2. Bank 1 sensor 1 refers to the sensor mounted in front of the three-way catalytic converter and located near the engine assembly.

The air fuel ratio sensor generates a voltage* that corresponds to the actual air fuel ratio. This sensor voltage is used to provide the hybrid vehicle control ECU with feedback so that it can control the air fuel ratio. The hybrid vehicle control ECU determines the deviation from the stoichiometric air fuel ratio level, and regulates the fuel injection time. If the air fuel ratio sensor malfunctions, the hybrid vehicle control ECU is unable to control the air fuel ratio accurately.

The air fuel ratio sensor is the planar type and is integrated with the heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the hybrid vehicle control ECU. When the intake air volume is low (the exhaust gas temperature is low), a current flows into the heater to heat the sensor, in order to facilitate accurate oxygen concentration detection. In addition, the sensor and heater portions are the narrow type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, therefore the sensor activation is accelerated.

In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxide (NOx) components in the exhaust gas, a three-way catalytic converter is used. For the most efficient use of the three-way catalytic converter, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric level.

*: Value changes inside the hybrid vehicle control ECU. Since the air fuel ratio sensor is a current output element, the current is converted into a voltage inside the hybrid vehicle control ECU. Any measurements taken at the air fuel ratio sensor or hybrid vehicle control ECU connectors will show a constant voltage.

Scheme 38

HINT

1. When any of these DTCs are set, check the air fuel ratio sensor voltage output by entering the following menus on the Techstream: Powertrain / Engine and ECT / Data List / All Data / AFS Voltage B1S1.
2. Short-term fuel trim values can also be read using the Techstream.
3. The hybrid vehicle control ECU regulates the voltages at the A1A+ and A1A- terminals of the hybrid vehicle control ECU to a constant level. Therefore, the air fuel ratio sensor voltage output cannot be confirmed without using the Techstream.
4. If an air fuel ratio sensor malfunction is detected, the hybrid vehicle control ECU sets a DTC.

Sensor Voltage Detection Monitor

Under the air fuel ratio feedback control, if the air fuel ratio sensor voltage output indicates rich or lean for a certain period of time, the hybrid vehicle control ECU determines that there is a malfunction in the air fuel ratio sensor. The hybrid vehicle control ECU illuminates the MIL and stores a DTC.

Example

If the air fuel ratio sensor voltage output is below 2.8 V (very rich condition) and heated oxygen sensor output voltage falls from 0.59 V or more to less than 0.21 V for 5 seconds, the hybrid vehicle control ECU stores DTC P2196. Alternatively, if the air fuel ratio sensor voltage output is higher than 3.8 V (very lean condition) and heated oxygen sensor output voltage rises from less than 0.21 V to 0.59 V or more for 5 seconds, DTC P2195 is stored.

Sensor Current Detection Monitor

A rich air fuel mixture causes a low air fuel ratio sensor current, and a lean air fuel mixture causes a high air fuel ratio sensor current. Therefore, the sensor output becomes low during acceleration, and it becomes high during deceleration with the throttle valve fully closed. The hybrid vehicle control ECU monitors the air fuel ratio sensor current during fuel-cut and detects any abnormal current values.

If the air fuel ratio sensor output is 3.6 mA or higher for more than 3 seconds of cumulative time, the hybrid vehicle control ECU interprets this as a malfunction in the air fuel ratio sensor and stores DTC P2195 (stuck on high side). If the air fuel ratio sensor output is below 1.0 mA for more than 3 seconds of cumulative time, the hybrid vehicle control ECU stores DTC P2196 (stuck on low side).

Scheme 39

HINT

1. Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor.
2. Bank 1 sensor 1 refers to the sensor mounted in front of the three-way catalytic converter and located near the engine assembly.

The air fuel ratio sensor, which is located between the exhaust manifold and catalyst, consists of alloyed metal elements and a heater.

Depending on the engine operating conditions, the heater heats the sensor elements to activate them. Battery voltage is applied to the heater and the sensor ground is controlled by the hybrid vehicle control ECU using a duty ratio.

The sensor elements convert the oxygen concentration in the exhaust gas into voltage values to output. Based on the voltage, the hybrid vehicle control ECU determines the air fuel ratio and regulates the fuel injection volume depending on the air fuel ratio and engine operating conditions. The voltage changes between 0.6 V and 4.5 V while the engine is running. If the air fuel ratio is lean, which means the oxygen concentration in the exhaust gas is high, the voltage is high. If the air fuel ratio is rich, which means the oxygen concentration in the exhaust gas is low, the voltage is low.

Scheme 40

These DTCs are output when there is an open or short in the air fuel ratio sensor circuit, or if air fuel ratio sensor output drops. To detect these problems, the voltage of the air fuel ratio sensor is monitored when turning the power switch on (IG), and the admittance (admittance is an electrical term that indicates the ease of flow of current) is checked while driving. If the voltage of the air fuel ratio sensor is between 0.5 V and 4.5 V, it is considered normal. If the voltage is out of the specified range, or the admittance is less than the standard value, the hybrid vehicle control ECU will determine that there is a malfunction in the air fuel ratio sensor. If the same malfunction is detected in next driving cycle, the MIL will be illuminated and a DTC will be stored.

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

HINT

Unit expression

1. (kPa-a [mmHg-a]) denotes absolute pressure.
2. (kPa-g [mmHg-g]) denotes gauge pressure (relative pressure).
3. On the Techstream, convert the unit of measurement according to the inspection procedure.

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

HINT

*1: If the engine coolant temperature is not below 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 below 35°C (95°F) 7 hours after the power switch is turned off, the monitor check starts 2.5 hours later.

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

P2420: Vent valve stuck open (vent)

In operation C, the vent valve turns on (closed) and the EVAP system pressure is then measured by the hybrid vehicle control ECU, using the canister pressure sensor, to conduct an EVAP leak check. If the pressure does not increase when the vent valve is open, the hybrid vehicle control ECU interprets this as the vent valve being stuck open. The hybrid vehicle control ECU illuminates the MIL and sets the DTC.

Scheme 41

The soak timer operates after the power switch is turned off. When a certain amount of time has elapsed after turning the power switch off, the soak timer activates the hybrid vehicle control ECU to perform malfunction checks which can only be performed after the engine is stopped. The soak timer is built into the hybrid vehicle control ECU.

Scheme 42

If the soak timer activates the hybrid vehicle control ECU even though only a short amount of time has elapsed since the power switch was turned off, or if the soak timer does not activate the hybrid vehicle control ECU even though a considerable amount of time has elapsed since the power switch was turned off, the hybrid vehicle control ECU determines that the soak timer is malfunctioning, illuminates the MIL and stores a DTC the next time the power switch is turned on (IG).

While the engine is running, the hybrid vehicle control ECU monitors the synchronization of the soak timer and the CPU clock. If these two are not synchronized, the hybrid vehicle control ECU interprets this as a malfunction, illuminates the MIL and sets the DTC (2 trip detection logic).

HINT

1. Refer to DTC P2195. Refer to «DESCRIPTION»(ref-398226-S30251047652011051600000) .
2. Bank 1 sensor 1 refers to the sensor mounted in front of the three-way catalytic converter and located near the engine assembly.

After the engine is warmed up, the hybrid vehicle control ECU performs air fuel ratio feedback control to maintain the air fuel ratio at the stoichiometric level. In addition, active air fuel ratio control is performed for approximately 15 to 25 seconds after preconditions are met in order to measure the air fuel ratio sensor response rate. During active air fuel ratio control, the hybrid vehicle control ECU forcibly increases and decreases the injection volume by a certain amount, based on the stoichiometric air fuel ratio learned during normal air fuel ratio control, and measures the air fuel ratio sensor response rate. The hybrid vehicle control ECU receives a signal from the air fuel ratio sensor while performing active air fuel ratio control and uses it to calculate the air fuel ratio sensor response rate deterioration level.

If the value for the air fuel ratio sensor response rate deterioration level is less than the threshold, the hybrid vehicle control ECU interprets this as a malfunction and stores the DTC.

Scheme 43

From the hybrid vehicle control ECU, the ECM (included in hybrid vehicle control ECU) receives data such as power output required for the engine (required output), estimated torque produced by the engine (estimated torque), engine speed of control target (target speed), and whether the engine is in start mode or not. Then, based on the required output and target speed, the ECM (included in hybrid vehicle control ECU) calculates a target torque that is to be produced by the engine and compares it with the estimated torque. If the estimated torque is very low compared with the target torque, or the engine start mode continues for the specific duration calculated by the coolant temperature, an abnormal condition is detected.

The ECM (included in hybrid vehicle control ECU) and hybrid vehicle control ECU are connected by a communication line called CAN. The ECM (included in hybrid vehicle control ECU) sends engine speed data and other data to the hybrid vehicle control ECU while the hybrid vehicle control ECU sends the information such as a requirement for the engine power to the ECM (included in hybrid vehicle control ECU) using the CAN communication line. When the communication between the ECM (included in hybrid vehicle control ECU) and hybrid vehicle control ECU is normal and the following items become a specified condition, the ECM (included in hybrid vehicle control ECU) illuminates the MIL and sets a DTC.

1. Engine speed
2. Target torque
3. Ratio of target torque against estimated torque
4. Fuel level

The Controller Area Network (CAN) is a serial data communication system for real-time application. It is a multiplex communication system designed for on-vehicle use that provides a superior communication speed of 500 kbps and a capability to detect malfunctions.

If the hybrid vehicle control ECU cannot receive signals from any of other ECUs due to a communication error, the hybrid vehicle control ECU illuminates the MIL and stores a DTC.

The Controller Area Network (CAN) is a serial data communication system for real-time application. It is a multiplex communication system designed for on-vehicle use that provides a superior communication speed of 500 kbps and a capability to detect malfunctions.

The hybrid vehicle control ECU sends and receives data to and from ECUs connected to the V1 bus and V2 bus. If a communication error occurs between the hybrid vehicle control ECU and one of these ECUs, the hybrid vehicle control ECU stores a DTC.

The ECM (included in hybrid vehicle control ECU) and the hybrid vehicle control ECU are located inside the hybrid vehicle control ECU. The engine control unit communicates with the hybrid vehicle control ECU through the controller Area Network (CAN).

If there is a communication problem, the hybrid vehicle control ECU sets a DTC.

When the power switch is turned on (IG), battery voltage is applied to IGSW of the hybrid vehicle control ECU. The output signal from the MREL terminal of the hybrid vehicle control ECU causes a current to flow to the coil, closing the contacts of the IGCT relay and supplying power to either terminal +B1 and +B2 of the hybrid vehicle control ECU.

Scheme 44

The hybrid vehicle control ECU constantly uses 5 V from the battery voltages supplied to the +B (BATT) terminal to operate the microprocessor. The hybrid vehicle control ECU also provides this power to the sensors through the VC output circuit.

Scheme 45

When the VC circuit is shorted, the microprocessor in the hybrid vehicle control ECU and sensors that are supplied power through the VC circuit are inactivated because the power is not supplied from the VC circuit. Under this condition, the system does not start up and the MIL does not illuminate even if the system malfunctions.

HINT

Under normal conditions, the MIL is illuminated for several seconds when the power switch is first turned on (IG). The MIL goes off when the engine is started.

Scheme 46

When the NE signal is input to the hybrid vehicle control ECU, Tr is turned on, current flows to the coil of the C/OPN relay, the relay switches on, power is supplied to the fuel pump and the fuel pump operates.

While the NE signal is generated (engine running), the hybrid vehicle control ECU keeps Tr on (circuit opening relay on) and the fuel pump also keeps operating.

Scheme 47

Scheme 48

The fuel injectors are located on the intake manifold. They inject fuel into the cylinders based on the signals from the hybrid vehicle control ECU.

Scheme 49

Scheme 50

1. CHECK FUEL INJECTOR ASSEMBLY (POWER SOURCE) Disconnect the fuel injector assembly connectors. Turn the power switch on (IG). Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Switch Condition Specified Condition C5-1 - Body ground Power switch on (IG) 11 to 14 V C6-1 - Body ground Power switch on (IG) 11 to 14 V C7-1 - Body ground Power switch on (IG) 11 to 14 V C8-1 - Body ground Power switch on (IG) 11 to 14 V TEXT IN ILLUSTRATION *1 Front view of wire harness connector (to Fuel Injector Assembly) Reconnect the fuel injector assembly connectors. NG --> See step 4 OK: Go to next step
2. INSPECT FUEL INJECTOR ASSEMBLY Inspect the fuel injector assembly. Refer to «INSPECTION»(/lexus/hs/i-2009-2012/remont/fuel-system/#fuel-service-information) . NG --> See step 5 OK: Go to next step
3. CHECK HARNESS AND CONNECTOR (FUEL INJECTOR ASSEMBLY - HYBRID VEHICLE CONTROL ECU) Disconnect the fuel injector assembly connectors. Disconnect the hybrid vehicle control ECU connector. Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Open) Tester Connection Condition Specified Condition C5-2 - C28-50 (#10) Always Below 1 ohms C6-2 - C28-64 (#20) Always Below 1 ohms C7-2 - C28-49 (#30) Always Below 1 ohms C8-2 - C28-63 (#40) Always Below 1 ohms Standard Resistance (Check for Short) Tester Connection Condition Specified Condition C5-2 or C28-50 (#10) - Body ground Always 10 ohms or higher C6-2 or C28-64 (#20) - Body ground Always 10 ohms or higher C7-2 or C28-49 (#30) - Body ground Always 10 ohms or higher C8-2 or C28-63 (#40) - Body ground Always 10 ohms or higher Reconnect the fuel injector assembly connectors. Reconnect the hybrid vehicle control ECU connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 6
4. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY (IG2 RELAY) - FUEL INJECTOR ASSEMBLY) Disconnect the fuel injector assembly connectors. Remove the integration relay from the engine room relay block. Disconnect the integration relay connector. Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Open) Tester Connection Condition Specified Condition C5-1 - 1A-4 Always Below 1 ohms C6-1 - 1A-4 Always Below 1 ohms C7-1 - 1A-4 Always Below 1 ohms C8-1 - 1A-4 Always Below 1 ohms Standard Resistance (Check for Short) Tester Connection Condition Specified Condition C5-1 or 1A-4 - Body ground Always 10 kohms or higher C6-1 or 1A-4 - Body ground Always 10 kohms or higher C7-1 or 1A-4 - Body ground Always 10 kohms or higher C8-1 or 1A-4 - Body ground Always 10 kohms or higher Reconnect the fuel injector assembly connectors. Reconnect the integration relay connector. Reinstall the integration relay. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 7
5. REPLACE FUEL INJECTOR ASSEMBLY. Refer to «REMOVAL»(/lexus/hs/i-2009-2012/remont/fuel-system/#fuel-service-information)
6. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-398225-S28102712272011051600000)
7. CHECK ECM POWER SOURCE CIRCUIT. Refer to «ECM Power Source Circuit»(ref-398226-S37492599822011051600000)

The MIL (Malfunction Indicator Lamp) is used to indicate vehicle malfunction detected by the hybrid vehicle control ECU. When the power switch is turned on (IG), power is supplied to the MIL circuit, and the hybrid vehicle control ECU provides the circuit ground which illuminates the MIL.

The MIL operation can be checked visually: When the power switch is first turned on (IG), the MIL should illuminate and should then turn off. If the MIL remains illuminated or is not illuminated, conduct the following troubleshooting procedure using the Techstream.

Scheme 51

Scheme 52

Scheme 53

1. CHECK THAT MIL IS ILLUMINATED Turn the power switch on (IG). Check the illumination of the MIL. Result Condition Proceed to MIL remains illuminated (Even after power switch is turned on (IG) and several seconds have passed, MIL still remains illuminated) A MIL remains off (Does not illuminate at all) B MIL illuminates for several seconds, but turns off after engine is started C C --> SYSTEM OK B --> See step 5 A: Go to next step
2. CHECK WHETHER MIL TURNS OFF Connect the Techstream to the DLC3. Turn the power switch on (IG). Turn the Techstream on. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes. Check if any DTCs have been stored. Note down the DTCs. Clear the DTCs. Refer to «DTC CHECK / CLEAR»(ref-398225-S11190546532011051600000) . Check if the MIL goes off. OK MIL goes off. NG --> See step 3 OK --> See step 8
3. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT IN WIRE HARNESS) Disconnect the hybrid vehicle control ECU connector. TEXT IN ILLUSTRATION *1 Front view of wire harness connector (to Hybrid Vehicle Control ECU) Turn the power switch on (IG). Check that the MIL is not illuminated. OK MIL is not illuminated. Reconnect the hybrid vehicle control ECU connector. NG --> See step 4 OK --> See step 9
4. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - HYBRID VEHICLE CONTROL ECU) Disconnect the combination meter assembly connector. Disconnect the hybrid vehicle control ECU connector. Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Short) Tester Connection Condition Specified Condition F4-28 (EFI) or A58-22 (W) - Body ground Always 10 kohms or higher Reconnect the combination meter assembly connector. Reconnect the hybrid vehicle control ECU connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 10
5. CHECK THAT ENGINE STARTS Turn the power switch on (IG). Put the engine in inspection mode. Refer to «INSPECTION MODE PROCEDURE»(ref-398089-S21258796492011051600000) . Start the engine. Result Result Proceed to Engine starts A Engine cannot be put in inspection mode* (Engine cannot start) B HINT: *: The Techstream cannot communicate with the hybrid vehicle control ECU. B --> See step 11 A: Go to next step
6. CHECK COMBINATION METER ASSEMBLY (TERMINAL VOLTAGE) Disconnect the hybrid vehicle control ECU connector. Turn the power switch on (IG). Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Switch Condition Specified Condition A58-22 (W) - Body ground Power switch on (IG) 11 to 14 V TEXT IN ILLUSTRATION *1 Front view of wire harness connector (to Hybrid Vehicle Control ECU) Reconnect the hybrid vehicle control ECU connector. NG --> See step 7 OK --> See step 9
7. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - HYBRID VEHICLE CONTROL ECU) Disconnect the combination meter assembly connector. Disconnect the hybrid vehicle control ECU connector. Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Open) Tester Connection Condition Specified Condition F4-28 (EFI) - A58-22 (W) Always Below 1 ohms Reconnect the hybrid vehicle control ECU connector. Reconnect the combination meter assembly connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 10
8. REPAIR CIRCUITS INDICATED BY OUTPUT DTCS. Refer to «DIAGNOSTIC TROUBLE CODE CHART»(ref-398225-S07453478932011051600000)
9. REPLACE HYBRID VEHICLE CONTROL ECU. Refer to «REMOVAL»(ref-398232-S36824664312011051600000)
10. REPLACE COMBINATION METER ASSEMBLY. Refer to «REMOVAL»(ref-398236-S19518532552011051600000)
11. GO TO VC OUTPUT CIRCUIT. Refer to «VC Output Circuit»(ref-398226-S39819149472011051600000)

See also:
• ON-VEHICLE INSPECTION - Step 1
• ON-VEHICLE INSPECTION - Step 2
• INSPECTION