Engine Control System (2GR-FXE) (Diagnostics & Circuit Tests) (Hybrid): Overview Toyota Highlander III

DESCRIPTION

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

Refer to DESCRIPTION

Scheme 492

1. P1451: Fuel tank pressure sensor abnormal voltage fluctuation or being constant If the fuel tank pressure sensor output voltage fluctuates rapidly for 10 seconds, the ECM stops the EVAP system monitor. The ECM interprets this as the fuel tank pressure sensor voltage fluctuating, and stops the EVAP system monitor. The ECM then illuminates the MIL and stores the DTC. Alternatively, if the sensor output voltage does not change, the ECM interprets this as the sensor voltage being constant, and stops the monitor. The ECM then illuminates the MIL and stores the DTC (2 trip detection logic).
2. P1452: Fuel tank pressure sensor voltage low If the fuel tank pressure sensor voltage output (pressure) is less than -17.1875 kPa(gauge) [-128.93 mmHg(gauge)], the ECM interprets this as an open or short circuit in the fuel tank 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. P1453: Fuel tank pressure sensor voltage high If the fuel tank pressure sensor voltage output (pressure) is higher than 23.9375 kPa(gauge) [179.57 mmHg(gauge)], the ECM interprets this as an open or short circuit in the 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).

If the engine does not start or it takes a long time for the engine to start, despite the ECM receiving the engine start request signal from the power management control ECU via CAN communication, this DTC will be stored.

Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

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When the engine is idling stably under a low load, if the idle speed drops or becomes unstable, this DTC will be stored.

Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

The throttle actuator is operated by the ECM 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 with motor assembly. The throttle position sensor provides feedback to the ECM. This feedback allows the ECM to appropriately control the throttle actuator and monitor the throttle opening angle as the ECM responds to driver inputs.

HINT

This Electronic Throttle Control System (ETCS) does not use a throttle cable.

MONITOR DESCRIPTION

The ECM 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 ECM 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 ECM determines that there is a malfunction. The ECM then illuminates the MIL and stores a DTC.

The idle speed is controlled by the Electronic Throttle Control System (ETCS). The ETCS is comprised of a throttle actuator, which operates the throttle valve, and a throttle position sensor, which detects the opening amount of the throttle valve. The ECM controls the throttle actuator to adjust the throttle valve opening amount so that the idle speed is maintained at the target idle speed.

HINT

1. The ISC learned value is the calculated intake air amount corresponding to the throttle opening amount necessary to maintain the idling speed.
2. This malfunction is only detected once per trip. After it has been detected once, the system will not monitor for the malfunction for the rest of the trip.
3. The system uses the throttle body with motor assembly and mass air flow meter sub-assembly to detect this malfunction.

If there are deposits in the throttle valve, a decrease in the ISC flow rate may cause engine stall or unstable idling. Therefore, the necessary ISC flow rate for idling is maintained using the ISC learned value and feedback. The ECM stores this DTC if the ISC learned value approaches its limit. The ECM begins monitoring for the DTC detection conditions when the following preconditions are met

1) The mass air flow meter sub-assembly is normal.

2) Atmospheric pressure is 85 kPa(abs) [637.6 mmHg(abs)] or higher.

3) The vehicle has been driven at a speed of 30 km/h (18.7 mph) or more at least once.

4) The engine coolant temperature is 45°C (113°F) or less at engine start, the engine is warmed up and conditions for ISC learning are met, or the power switch has been turned on (IG) (including when the engine is running) for 1 hour or more, the engine is warmed up and conditions for ISC learning are met.

The throttle actuator is operated by the ECM, 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 with motor assembly. The throttle position sensor provides feedback to the ECM. This feedback allows the ECM to appropriately control the throttle actuator and monitor the throttle opening angle as the ECM responds to driver inputs.

HINT

This Electronic Throttle Control System (ETCS) does not use a throttle cable.

The ECM determines that there is a malfunction in the ETCS when the throttle valve remains at a fixed angle despite a high drive current from the ECM. The ECM then illuminates the MIL and stores a DTC.

The electronic throttle control system has a dedicated power supply circuit. The voltage (+BM) is monitored and when it is low (less than 4 V), the ECM 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 ECM then allows the current to flow to the throttle actuator so that it can be restarted.

HINT

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

Scheme 494

The ECM monitors the auxiliary battery supply voltage applied to the throttle actuator.

When the power supply voltage (+BM) is less than 4 V for 0.8 seconds or more, the ECM interprets this as an open in the power supply circuit (+BM). The ECM then illuminates the MIL and stores this DTC.

The electronic throttle control system is composed of the throttle actuator, throttle position sensor, accelerator pedal position sensor, and ECM. The ECM 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 ECM with feedback so that the throttle valve can be appropriately controlled by the ECM.

The ECM 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 ECM. If the difference between these two values is outside the standard range, the ECM interprets this as a malfunction in the electronic throttle control system. The ECM then illuminates the MIL and stores this DTC.

HINT

Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor.

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

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

In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (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 ECM. Since the air fuel ratio sensor is a current output element, the current is converted into a voltage inside the ECM. Any measurements taken at the air fuel ratio sensor or ECM connectors will show a constant voltage.

Scheme 495

HINT

1. DTCs P2195 and P2196 indicate malfunctions related to the bank 1 air fuel ratio sensor circuit.
2. DTCs P2197 and P2198 indicate malfunctions related to the bank 2 air fuel ratio sensor circuit.
3. When any of these DTCs are stored, check the air fuel ratio sensor voltage output by entering the following menus on the Techstream: Powertrain / Engine and ECT / Data List / Gas AF Control / AFS Voltage B1S1 or AFS Voltage B2S1.
4. Short-term fuel trim values can also be read using the Techstream.
5. The ECM regulates the voltages at the A1A+, A2A+, A1A- and A2A- terminals of the ECM to a constant level. Therefore, the air fuel ratio sensor output voltage cannot be confirmed without using the Techstream.
6. If an air fuel ratio sensor malfunction is detected, the ECM will store a DTC.

Sensor Voltage Detection Monitor

Under air fuel ratio feedback control, If the air fuel ratio sensor output voltage is less than 2.8 V (very rich condition) for 5 seconds despite the heated oxygen sensor output voltage being less than 0.66 V, the ECM stores DTC P2196 or P2198. Alternatively, if the air fuel ratio sensor output voltage is higher than 3.8 V (very lean condition) for 5 seconds despite the heated oxygen sensor output voltage being 0.21 V or higher, DTC P2195 or P2197 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 ECM monitors the air fuel ratio sensor current during fuel-cut and detects any abnormal current values.

If the air fuel ratio sensor output is 2.2 mA or higher for more than 3 seconds of cumulative time, the ECM interprets this as a malfunction in the air fuel ratio sensor and stores DTC P2195 or P2197 (stuck on high side). If the air fuel ratio sensor output is less than 0.7 mA for more than 3 seconds of cumulative time, the ECM stores DTC P2196 or P2198 (stuck on low side).

Scheme 496

Refer to DTC P0300.

Refer to DESCRIPTION

Refer to DTC P2195, P2197.

Refer to DESCRIPTION

Fuel System Air Fuel Ratio Cylinder Imbalance Monitor

The ECM uses the air fuel ratio sensor and crankshaft position sensor to monitor the difference in air fuel ratios between the cylinders caused by differences in injection volumes between the cylinders, leakage in the intake or exhaust system, etc.

When the air fuel ratios of the cylinders are lean or rich with respect to each other, the ECM determines that there is a malfunction, illuminates the MIL and stores a DTC.

Air Fuel Ratio Sensor Monitoring Method: P219A and/or P219B are stored primarily when a rich side imbalance is detected.

When the system detects a difference in air fuel ratios between the cylinders due to fluctuation in the air fuel ratio sensor output over 1 engine cycle (2 crankshaft revolutions), the ECM determines that there is a malfunction.

Crankshaft Position Sensor Monitoring Method: P219C, P219D, P219E, P219F, P21A0 and/or P21A1 are stored primarily when a lean side imbalance is detected.

The system monitors the engine speed variation and when the variation becomes large, the ECM determines that there is a difference in air fuel ratios between the cylinders, which it determines to be a malfunction.

Refer to DTC P2195.

Refer to DESCRIPTION

These DTCs are output when there is an open or short in the air fuel ratio sensor circuit, or if the 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 ECM determines that there is a malfunction in the air fuel ratio sensor. If the same malfunction is detected in the next driving cycle, the ECM will illuminate the MIL and store a DTC.

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

Refer to DESCRIPTION

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 ECM using the canister pressure sensor to conduct an EVAP leak check. If the pressure does not increase when the vent valve is open, the ECM interprets this as the vent valve being stuck open. In this case the ECM will illuminate the MIL and store this DTC.

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Scheme 498

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

Refer to DESCRIPTION

1. P2450: Fuel vapor-containment valve stuck open During sequence C, the leak detection pump creates vacuum in the EVAP system. If the pressure in the fuel tank drops, the ECM determines that the fuel vapor-containment valve is stuck open. The ECM then illuminates the MIL and stores the DTC (2 trip detection logic).
2. P2451: Fuel vapor-containment valve stuck closed (vent) During sequence I, the fuel vapor-containment valve opens to allow atmospheric pressure into the fuel tank. If there is no change in fuel tank pressure, the ECM determines that the fuel vapor-containment valve is stuck closed. The ECM then illuminates the MIL and stores the DTC (2 trip detection logic). During sequence G, the fuel vapor-containment valve opens to allow vacuum pressure generated by the leak detection pump into the fuel tank. If the pressure in the fuel tank does not drop, the ECM determines that the fuel vapor-containment valve is stuck closed. The ECM then illuminates the MIL and stores the DTC (2 trip detection logic).

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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 ECM to perform malfunction checks which can only be performed after the engine is stopped. The soak timer is built into the ECM.

Scheme 501

If the soak timer activates the ECM 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 ECM even though a considerable amount of time has elapsed since the power switch was turned off, the ECM determines that the soak timer is malfunctioning, illuminates the MIL and stores this DTC the next time the power switch is turned on (IG).

The ECM receives signals from the power management control ECU such as the requested engine torque, target engine speed and engine cranking status, and controls the engine output based on the target engine speed and requested torque.

1. The ECM receives signals such as requested engine torque, target engine speed and engine cranking status from the power management control ECU.
2. The ECM controls engine start and stop and throttle valve angle based on the signals received from the power management control ECU.
3. The ECM receives the actual engine torque calculated by the power management control ECU based on the generator torque.
4. When the actual engine torque is less than 20% of the requested engine torque*, the ECM judges that the engine output is abnormal and stores DTC P3190. (The engine may not have started in the above situation.) *: Requested torque = Requested Engine Torque (kW) / HV Target Engine Speed (RPM) x 9549
5. If the ECM does not detect engine start torque (actual engine torque) even though it has received an engine start request and started the engine, it stores DTC P3191. HINT: When DTC P3190, P3191 or P3193 is stored, engine operation is disabled. In this case, add fuel or perform a repair, then clear the DTCs and turn the power switch off to allow the operation to return to normal. When DTC P3190, P3191 or P3193 is stored, the HV battery is not charged as the vehicle operates using only the motor. If the vehicle is driven in this condition, the SOC will drop and the HV battery will be depleted, preventing the system from entering the READY-on state. When DTC P3190 or P3191 is stored, the engine torque has dropped by 80 % or the engine cannot be started. If any DTCs that indicate malfunctioning of engine related parts are stored at the same time, repair the malfunctioning parts first. Relevant Data List Items: ECM (Powertrain / Engine and ECT / Data List) HV Target Engine Speed Engine Speed Requested Engine Torque Actual Engine Torque Throttle Position Command Throttle Position No. 1 Calculate Load Coolant Temp Short FT #1, #2 Long FT #1, #2 EGR Step Position - POWER MANAGEMENT CONTROL ECU (Powertrain / Hybrid Control / Data List) Target Engine Rev Engine Revolution Requested Engine Torque Engine Coolant Temp Engine Idling Request

The ECM receives the fuel low level signal from the combination meter sub-assembly (meter ECU) to detect if the vehicle is running out of fuel.

This DTC indicates that the vehicle ran out of fuel. If the ECM receives the fuel low level signal from the combination meter sub-assembly (meter ECU) and the DTC detection conditions of either DTC P3190 or P3191 are met while the power switch is on (IG) or the engine is operating, the ECM stores this DTC.

The CAN (Controller Area Network) 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. Through the combination of the CANH and CANL bus lines, the CAN is able to maintain communication based on differential voltage.

While the engine is running, if predetermined conditions (closed loop, etc.) are met, the purge VSV is opened by the ECM and stored fuel vapors in the canister are purged to the intake manifold. The ECM will change the duty cycle ratio of the purge VSV to control purge flow volume.

Purge flow volume is also determined by the intake manifold pressure. Atmospheric pressure is allowed to enter the canister through the vent valve to ensure that purge flow is maintained when negative pressure (vacuum) is applied to the canister.

The ECM monitors the condition of both the key-off monitor and purge flow monitor to ensure proper operation of the EVAP system.

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1. Key-off monitor This monitor checks for EVAP (evaporative emission) system leaks and canister pump module malfunctions. The monitor starts 5 hours* after the power switch is turned off. At least 5 hours are required for the fuel to cool down to stabilize the EVAP pressure, thus making the EVAP system monitor more accurate. The leak detection pump creates negative pressure (vacuum) in the EVAP system and the pressure is measured. Finally, the ECM monitors for leaks from the EVAP system, and malfunctions in both the canister pump module and purge VSV 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 the fuel tank pressure is higher or lower than the atmospheric pressure, the system determines that there are no leaks in the closed tank system and the system will check for leaks from the piping and canister between the purge VSV and canister pump module. (Method A) If the fuel tank pressure is almost the same as the atmospheric pressure, vacuum will be allowed to enter the fuel tank and the system will check for leaks from the fuel tank after checking for leaks from the canister. (Method B) Sequence Operation Description Duration - ECM activation Activated by soak timer, 5 hours (7 or 9.5 hours) after power switch turned off. - A Atmospheric pressure measurement Vent valve turned off (vent) and EVAP system pressure is measured by ECM in order to register atmospheric pressure. by ECM in order to register atmospheric pressure.If pressure in EVAP system is not between 70 kPa(abs) and 111 kPa(abs) [525 mmHg(abs) and 832 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 values as they 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 opens and then EVAP system pressure is measured by ECM. Large increase indicates normal. 10 seconds E Second reference pressure measurement After second reference pressure measurement, leak check is performed by comparing first and second reference pressure. If stabilized system pressure is higher than second reference pressure, ECM determines that EVAP system has a leak. 60 seconds F Resetting Fuel tank pressure is compared with atmospheric pressure. If tank pressure is higher than PH or lower than PL, ECM determines that EVAP system is normal and runs sequence I in method A. If tank pressure is around atmospheric pressure, ECM performs sequence G in method B. 5 seconds G Fuel tank pressure measurement Vent valve is turned on (closed). Fuel vapor-containment valve opens to allow negative pressure to enter the fuel tank and fuel tank pressure is measured. Write down measured values because they will be used in leak check. If fuel tank pressure does not stabilize within 15 minutes, ECM stops monitoring. 15 minutes* H Third reference pressure measurement After third reference pressure measurement, leak check of fuel tank is performed. If recorded fuel tank pressure is higher than third reference pressure, ECM determines that EVAP system has a leak. 60 seconds I Fuel vapor-containment valve stuck closed check Fuel vapor-containment valve is opened for a certain period of time to check whether the valve is stuck closed. 0.1 second J Final check Atmospheric pressure is measured and then monitoring result is recorded by ECM. - HINT: *: If there is only a small amount of fuel in the fuel tank, stabilizing the EVAP pressure takes longer than usual. *1 Canister *2 Reference Orifice (0.02 inch) *3 Canister Pressure Sensor *4 Purge VSV *5 Fuel Vapor-containment Valve *6 Fuel Tank Pressure Sensor *7 Fuel Tank *8 Canister Pump Module *9 Vent Valve: OFF (Vent) *10 Canister Filter *11 Leak Detection Pump: OFF *12 OFF *13 ON *14 OFF (Vent) *15 ON (Closed) - - *a Operation A, F *b Operation B, E, H *c Operation C *d Operation D *e Operation G *f Atmospheric Pressure *g Negative Pressure
2. Purge flow monitor The purge flow monitor consists of the 2 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 (Vacuum Switching Valve) 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. 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 in atmospheric pressure, before and after of the purge flow monitor, is measured by the ECM. *1 ECM *2 Soak Timer *3 Fuel Cap *4 Canister Filter *5 Fuel Tank *6 Canister Pressure Sensor *7 Reference Orifice (0.02 inch) *8 Canister Pump Module *9 Canister *10 Fuel Vapor-containment Valve *11 Fuel Outlet Valve (Relief Valve) *12 Fuel Tank Pressure Sensor *a EVAP Purge Flow *b to Intake Manifold *c Purge VSV (on) *d Leak Detection Pump (off) *e Vent Valve (off)

When the power switch is turned on (IG), auxiliary battery voltage is applied to the IGSW terminal of the ECM. The output signal from the MREL terminal of the ECM causes current to flow to the coil of the semiconductor pwr integration ECU (EFI MAIN relay), closing the contacts of the EFI MAIN relay and supplying power to terminals +B and +B2 of the ECM.

Scheme 512

The ECM constantly generates 5 V power source voltage from the auxiliary battery voltages supplied to the +B (BATT) terminal to operate the microprocessor. The ECM also provides this power source voltage to the sensors through the VC output circuit.

Scheme 513

When the VC circuit is shorted, the microprocessor in the ECM 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 when the power switch is turned on (IG). The MIL goes off when the power switch on (READY).

Scheme 514

Refer to DTC P0230.

Refer to DESCRIPTION

Scheme 515

The fuel injector assemblies are located on the intake port. They inject fuel into the cylinders based on the signals from the ECM.

Scheme 516

The Malfunction Indicator Lamp (MIL) is used to indicate vehicle malfunctions detected by the ECM.

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

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See also:
• ON-VEHICLE INSPECTION [02/2014 - ]
• PROCEDURE - Step 2
• PROCEDURE - Step 3
• PROCEDURE - Step 10