Engine Control System (1AR-FE) (Diagnostic Codes (P0420-P1605): Overview Toyota Venza I facelift

MONITOR DESCRIPTION

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

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

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

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

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

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TEXT IN ILLUSTRATION

Note. Replace the exhaust manifold converter sub-assembly (*1) and the center exhaust pipe assembly (*5) together when catalyst replacement is necessary. (Excluding air fuel ratio sensor *2 and heated oxygen sensor *3)

DESCRIPTION

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 below 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 below 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 186

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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 187

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.

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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 below 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 below 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. TEXT IN ILLUSTRATION *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. The ECM illuminates the MIL and stores the DTC (2 trip detection logic). Purge VSV stuck closed In operation D, the canister pressure sensor measures the EVAP (Evaporative Emission) system pressure. The pressure measurement for the purge VSV monitor begins when the purge VSV is turned on (open) after the EVAP leak check. When the measured pressure indicates an increase of 0.3 kPa(gauge) [2.25 mmHg(gauge)] or 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 pressures, before and after conduction of the purge flow monitor, is measured by the ECM.

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

Scheme 191

1. DTC P0451: Canister pressure sensor abnormal voltage fluctuation or being constant If the canister pressure sensor voltage output fluctuates rapidly for 10 seconds, the ECM stops the EVAP system monitor. The ECM interprets this as the canister pressure sensor voltage fluctuating, and stops the EVAP system monitor. The ECM then illuminates the MIL and stores the DTC. Alternatively, if the sensor voltage output does not change for 2 minutes, the ECM interprets this as the sensor being stuck, and stops the monitor. The ECM then illuminates the MIL and stores the DTC. (Both the malfunctions are detected by 2 trip detection logic).
2. DTC P0452: Canister pressure sensor voltage low If the canister pressure sensor voltage output (pressure) is less than 0.45 V: 42.11009 kPa(abs) [315.86779 mmHg(abs)], the ECM interprets this as an open or short circuit in the canister pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and stores the DTC (1 trip detection logic).
3. DTC P0453: Canister pressure sensor voltage high If the canister pressure sensor voltage output (pressure) is higher than 4.9 V: 123.76147 kPa(abs) [928.33479 mmHg(abs)], the ECM interprets this as an open or short circuit in the canister pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and stores the DTC (1 trip detection logic).

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

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

HINT

*: If the engine coolant temperature is not below 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 below 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.

TEXT IN ILLUSTRATION

Scheme 192

1. (a) P0455: EVAP (Evaporative Emission) gross leak In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than [second reference pressure x 0.2] (near atmospheric pressure), the ECM determines that the EVAP system has a large leak, illuminates the MIL and stores the DTC (2 trip detection logic).
2. (b) P0456: EVAP very small leak In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than second reference pressure, the ECM determines that the EVAP system has a small leak, illuminates the MIL and stores the DTC (2 trip detection logic).

The speed sensor detects the wheel speed and sends the appropriate signals to the skid control ECU.

The skid control ECU converts these wheel speed signals into a 4-pulse signal and outputs it to the ECM via the combination meter. The ECM determines the vehicle speed based on the frequency of these pulse signals.

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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 the DTC.

The stop light switch is a duplex system that transmits 2 signals: STP and ST1-. These 2 signals are used by the ECM to monitor whether or not the brake system is working properly. If 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 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.

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The idle speed is controlled by the electronic throttle control system. The electronic throttle control system is comprised of: 1) the one-valve-type throttle body; 2) the throttle actuator, which operates the throttle valve; 3) the throttle position sensor, which detects the opening angle of the throttle valve; 4) the accelerator pedal position sensor, which detects the accelerator pedal position; and 5) the ECM, which controls the electronic throttle control system. Based on the target idle speed, the ECM controls the throttle actuator to provide the proper throttle valve opening angle.

The ECM monitors the idling speed and idling air flow volume to conduct Idle Speed Control (ISC). The ECM determines that the ISC system is malfunctioning if either of the following conditions is met

Scheme 196

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

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

The electronic throttle control system controls the idle speed. The 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.

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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 below 50°C (122°F), the ECM checks the ignition timing during engine idling. If the ignition timing advances beyond the specified level within 10 seconds, the ECM interprets this as a malfunction. The MIL is illuminated and a DTC is 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.

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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 stored ECM data is cleared and the ECM determines that there is a malfunction in the power supply circuit. When the engine is next started, the ECM will illuminate the MIL and set the DTC.

HINT

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

The ECM continuously monitors its internal memory status. This self-check ensures that the ECM 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 standard, the ECM illuminates the MIL and stores the DTC immediately.

The ECM continuously monitors its main and sub CPUs. This self-check ensures that the ECM is functioning properly. If outputs from the CPUs are different and deviate from the standard, the ECM illuminates the MIL and stores the DTC immediately.

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

The main CPU and sub CPU of the ECM perform data communication between each other. The main CPU monitors the communications and WDC pulses from the sub CPU. When the signal malfunctions below are detected, the DTC is output.

This DTC is stored when a communication error occurs in the ECM.

The ECM monitors the input signals of the accelerator pedal position sensor No. 1. When the input signals and control signals are deviated, the DTC is stored.

The ECM monitors the input signals of the throttle position sensor No. 1 and stop light switch. As the ECM monitors the input signals of the throttle position sensor No. 1 and the STP signals of the stop light switch, if the input signals and control signals are deviated, the DTC is stored.

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

This monitor runs when the vehicle is driven at 12.43 mph (20 km/h) or more for over 20 seconds.

The ECM monitors its internal operation and it stores this DTC when it detects an internal malfunction.

The ECM monitors its internal operation. If the internal operation is malfunctioning, the ECM illuminates the MIL and stores a DTC.

DTC P0630 is stored when the Vehicle Identification Number (VIN) is not stored in the Engine Control Module (ECM) or the input VIN is not accurate. Input the VIN with the Techstream.

The ECM monitors the output voltage to the throttle actuator. This self-check ensures that the ECM is functioning properly. The output voltage is usually 0 V when the ignition switch is turned off. If the output voltage is higher than 7 V when the ignition switch is turned off, the ECM illuminates the MIL and stores the DTC when the ignition switch is turned to ON.

The park/neutral position switch assembly detects the shift lever position and sends signals to the ECM.

These DTCs indicate a problem with the park/neutral position switch assembly and the wire harness in the park/neutral position switch circuit.

The park/neutral position switch assembly detects the shift lever position and sends a signal to the ECM.

For security, the park/neutral position switch assembly detects the shift lever position so that the engine can be started only when the shift lever is in P or N.

The park/neutral position switch assembly sends a signal to the ECM according to the shift lever position (P, R, N, D, or S). The ECM determines that there is a problem with the switch or related parts if it receives more than 1 position signal simultaneously. The ECM will turn on the MIL and store the DTC.

The purpose of this circuit is to prevent the engine from stalling when brakes are suddenly applied while driving in lock-up condition.

When the brake pedal is depressed, the stop light switch sends a signal to the ECM. Then the ECM cancels the operation of the lock-up clutch while braking is in progress.

This DTC indicates that the stop light switch remains on. When the stop light switch remains on during "stop and go" driving, the ECM interprets this as a fault in the stop light switch. The ECM turns on MIL and stores the DTC. The vehicle must stop (less than 1.86 mph [3 km/h]) and go (18.65 mph [30 km/h] or more) 5 times during 2 driving cycles, in order to detect a malfunction.

P1603

After starting the engine, this DTC is stored when the engine stops without the ignition switch being operated.

Using the Techstream, the conditions present when the DTC was stored can be confirmed by referring to the freeze frame data. Freeze frame data records engine conditions when a malfunction occurs. This information can be useful when troubleshooting.

It is necessary to check if the vehicle has ran out of fuel before performing troubleshooting, as this DTC is also stored when the engine stalls due to running out of fuel.

P1605

This DTC is stored if the engine speed drops below the set speed.

Using the Techstream, the conditions present when the DTC was stored can be confirmed by referring to the freeze frame data. Freeze frame data records engine conditions when a malfunction occurs. This information can be useful when troubleshooting.

It is necessary to check if the vehicle ran out of fuel before performing troubleshooting, as this DTC is also stored when idling is unstable due to running out of fuel.

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1. Reference waveforms showing a normal cold engine start
2. Reference waveforms showing a normal warm engine start
3. Reference values when there is an air leak in the intake system during rough idling FREEZE FRAME DATA P1605 ROUGH IDLING Parameter -3 -2 -1 0 1 Unit Engine Speed 533 516 612 420 416 rpm Calculate Load 39.2 40.0 40.0 41.1 42.3 % Vehicle Load 24.7 27.0 16.8 40.7 35.2 % MAF 3.56 3.75 2.81 4.59 3.93 gm/s Atmosphere Pressure 14.5 14.5 14.5 14.5 14.5 psi(gauge) Coolant Temp 85 85 85 85 85 °C Intake Air 46 46 46 46 46 °C Battery Voltage 13.105 13.144 13.359 12.949 12.910 V Throttle Sensor Volt % 17.2 15.6 15.2 16.8 16.4 % Throttl Sensor #2 Volt % 49.4 47.4 47.0 49.0 48.6 % Throttle Sensor Position 0.0 0.0 0.0 0.0 0.0 % Throttle Motor DUTY 17.6 15.2 15.2 15.2 16.8 % Injector (Port) 4160 4194 4056 4979 5042 μs Injection Volum (Cylinder 1) 0.175 0.175 0.228 0.228 0.228 ml Fuel Pump/Speed Status ON ON ON ON ON EVAP (Purge) VSV 0.0 0.0 0.0 0.0 0.0 % Evap Purge Flow 0.0 0.0 0.0 0.0 0.0 % Purge Density Learn Value 0.000 0.000 0.000 0.000 0.000 EVAP Purge VSV OFF OFF OFF OFF OFF Target Air-Fuel Ratio 0.999 0.999 0.999 0.999 0.999 AF Lambda B1S1 1.232 1.232 1.232 1.232 1.232 AFS Voltage B1S1 4.996 4.996 4.996 4.996 4.996 V O2S B1S2 0.000 0.000 0.000 0.000 0.000 V Short FT #1 18.750 18.750 18.750 18.750 18.750 % Long FT #1 3.906 3.906 3.906 3.906 3.906 % Total FT #1 0.000 0.000 0.000 0.000 0.000 Fuel System Status #1 CL CL CL CL CL IGN Advance 15.0 14.0 14.5 15.0 0.5 deg Knock Feedback Value -3.0 -3.0 -3.0 -3.0 -3.0 deg(CA) Knock Correct Learn Value 19.0 19.0 19.0 19.0 19.0 deg(CA) VVT Control Status #1 OFF OFF OFF OFF OFF Starter Signal OFF OFF OFF OFF OFF

See also:
• REMOVAL [08/2013 - ]
• ON-VEHICLE INSPECTION [08/2013 - ]
• ON-VEHICLE INSPECTION [08/2013 - ]
• ON-VEHICLE INSPECTION [08/2013 - ]