Engine Control (1AR-FE) (Diagnostic Codes (P0500-U0101) & Circuit Tests): Overview Toyota Venza I

DESCRIPTION

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.

Scheme 76

*1: w/ Smart Key System

*2: w/ Navigation System

*3: for Separate Type Amplifier System

*4: w/ Automatic Type Headlight Beam Level Control

MONITOR DESCRIPTION

The ECM assumes that the vehicle is being driven, when the indicated engine speed is more than 2300 rpm and 30 seconds have elapsed since the park/neutral position switch was turned off. If there is no speed signal from the combination meter despite these conditions being met, the ECM interprets this as a malfunction in the speed signal circuit. The ECM then illuminates the MIL and sets 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.

Scheme 77

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON and turn the Techstream on.
3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
4. Turn the ignition switch off and wait for at least 30 seconds.
5. Turn the ignition switch to ON and turn the Techstream on [A].
6. Depress and release the brake pedal [B].
7. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
8. Input the DTC: P0504.
9. Check the DTC judgment result [C]. Techstream Display Description NORMAL DTC judgment completed System normal ABNORMAL DTC judgment completed System abnormal INCOMPLETE DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions UNKNOWN Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit HINT: If the judgment result shows ABNORMAL, the system has a malfunction.
10. If the test result is UNKNOWN, enter the following menus: Powertrain / Engine / Trouble Codes / Pending.
11. Read Pending DTCs. HINT: If a pending DTC is output, the system is malfunctioning.
12. If the test result is INCOMPLETE or UNKNOWN and no pending DTC is output, perform a universal trip and check for permanent DTCs. Refer to «DTC CHECK / CLEAR»(ref-394618-S22943830982011040800000). HINT: If a permanent DTC is output, the system is malfunctioning. If no permanent DTC is output, the system is normal.

Scheme 78

Scheme 79

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

Scheme 80

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 when the A/C and NSW are off, or less than -100 rpm or 200 rpm or more when the A/C or NSW are on, 5 times or more during a driving cycle, the ECM illuminates the MIL and sets the DTC.

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. When the cable is disconnected from the negative (-) battery terminal during inspections or repairs, the idle speed control learned values are cleared. This DTC cannot be stored with the idle speed control learned values cleared.

HINT

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

Scheme 81

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. When the cable is disconnected from the negative (-) battery terminal during inspections or repairs, the idle speed control learned values are cleared. This DTC cannot be stored with the idle speed control learned values cleared.

HINT

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

Scheme 82

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 set, the ECM does not store other DTCs.

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.

The ECM continuously monitors its main and sub CPUs while cruise control is operating. 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 tumble control valve is built into the intake manifold. The tumble control valve is composed of a position sensor and a DC motor. The DC motor opens and closes the tumble control valve in response to signals from the ECM. The position sensor detects the opening angle of the tumble control valve.

When the tumble control valve is closed, the intake air tumble flow intensifies and negative pressure is generated between the tumble control valve and intake valve which atomizes the fuel. Combustion is enhanced and exhaust gas emissions are reduced at low temperatures.

HINT

After confirming DTCs P2004 and/or P2006, use the Techstream to confirm the Intake Air Control Position while performing Control the IAC Duty Ratio of the Active Test.

REFERENCE (NORMAL CONDITION)

REFERENCE (NORMAL CONDITION)

When the ECM has requested a tumble control valve close operation but the actual tumble control valve opening angle is 17 deg or more for 10 seconds, DTC P2004 is output. When the ECM has requested a tumble control valve open operation but the actual tumble control valve opening angle is less than 35 deg for 10 seconds, DTC P2006 is output.

The ECM activates the DC motor for the tumble control valve, which opens and closes the tumble control valve. The ECM activates the DC motor based on engine speed, coolant temperature, intake air temperature and other conditions.

When the voltage of the DC motor deviates from the standard range, the ECM determines that a malfunction has occurred and outputs a DTC.

The tumble control valve position sensor is a non-contact type sensor.

The position sensor measures the opening angle of the tumble control valve. The sensor is reliable and accurate, as it is electrically controlled by Hall elements.

Scheme 83

HINT

After confirming DTC P2014, P2016 or P2017, use the Techstream to confirm the IAC Sensor Voltage (tumble control valve position sensor output voltage). Enter the following menus: Powertrain / Engine / Data List / All Data / IAC Sensor Voltage.

The ECM IAC1 terminal voltage increases in correlation with the opening angle of the tumble control valve. When the tumble control valve is fully closed, approximately 0.8 V is applied to the IAC1 terminal. When the tumble control valve is fully open, approximately 3.6 V is applied to the IAC1 terminal.

When the output voltage of the IAC1 terminal deviates from the standard range, the ECM determines that a malfunction has occurred in the position sensor and stores a DTC.

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. 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 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.

1. Example: When the electrical current is below 0.5 A and the throttle actuator duty ratio exceeds 80%, the ECM interprets this as the current being outside the standard range, illuminates the MIL and stores a DTC. If the malfunction is not repaired successfully, a DTC is stored when the engine is quickly revved to a high rpm several times after the engine has idled for 5 seconds after engine start.

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. 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 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 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 ignition 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 84

The ECM 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 ECM interprets this as an open in the power supply circuit (+BM). The ECM 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 sensor assembly, 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 2 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 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 fully depressing the accelerator pedal (fully open the throttle valve).

HINT

1. This Electronic Throttle Control System (ETCS) does not use a throttle cable.
2. These DTCs relate to the accelerator pedal sensor assembly.

The accelerator pedal sensor assembly is mounted on the accelerator pedal bracket and has 2 sensor circuits: VPA (main) and VPA2 (sub). This sensor is a non-contact type sensor and uses Hall-effect elements in order to yield accurate signals even in extreme driving conditions, such as at high speeds as well as very low speeds. The voltage, which is applied to terminals VPA and VPA2 of the ECM, varies between 0.5 V and 4.5 V in proportion to the operating angle of the accelerator pedal (throttle valve). A signal from VPA indicates the actual accelerator pedal angle (throttle valve opening angle) and is used for engine control. A signal from VPA2 conveys the status of the VPA circuit and is used to check the accelerator pedal sensor assembly itself.

The ECM monitors the actual accelerator pedal angle (throttle valve opening angle) through the signals from VPA and VPA2, and controls the throttle actuator according to these signals.

Scheme 85

HINT

When any of these DTCs are output, check the accelerator pedal sensor assembly voltage using the Techstream. Enter the following menus: Powertrain / Engine / Data List / All Data / Accel Sensor Out No. 1 and Accel Sensor Out No. 2.

HINT

Accelerator pedal positions are expressed as voltages.

When either output voltage of VPA or VIP deviates from the standard range, or the difference between the output voltages of the 2 sensor circuits is less than the threshold, the ECM determines that there is a malfunction in the accelerator pedal position sensor. The ECM then illuminates the MIL and stores a DTC.

Example

When the output voltage of VPA drops below 0.4 V for more than 0.5 seconds when the accelerator pedal is fully depressed, DTC P2122 is stored.

If the malfunction is not repaired successfully, a DTC is stored 2 seconds after the engine is next started.

HINT

1. This DTC relates to the accelerator pedal sensor assembly.

Refer to DTC P2120. Refer to DESCRIPTION.

The accelerator pedal position sensor is mounted on the accelerator pedal bracket. The accelerator pedal position sensor has 2 sensor elements and 2 signal outputs: VPA and VPA2. VPA is used to detect the actual accelerator pedal angle (used for engine control) and VPA2 is used to detect malfunctions in VPA. When the difference between the output voltages of VPA and VPA2 deviates from the standard, the ECM determines that the accelerator pedal position sensor is malfunctioning. The ECM turns on the MIL and stores the DTC.

HINT

1. Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor.
2. 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 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 the planar type and is integrated with the 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), 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), 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 86

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 / Data List / All Data / AFS Voltage B1 S1.
2. Short-term fuel trim values can also be read using the Techstream.
3. The ECM regulates the voltages at the A1A+ and A1A- terminals of the ECM 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 ECM 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 ECM determines that there is a malfunction in the air fuel ratio sensor. The ECM 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 ECM 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 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 3.6 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 (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 ECM stores DTC P2196 (stuck on low side).

Scheme 87

HINT

1. Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor.
2. 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 ECM 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 ECM 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 that the oxygen concentration in the exhaust gas is high, the voltage is high. If the air fuel ratio is rich, which means that the oxygen concentration in the exhaust gas is low, the voltage is low.

Scheme 88

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 ignition switch to ON, 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 0.6 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 next driving cycle, the MIL is illuminated and a DTC is stored.

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 89

P2420: Vent valve stuck open (vent)

In operation C, the vent valve turns ON (closes) 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. The ECM illuminates the MIL and stores the DTC.

Scheme 90

The soak timer operates after the ignition switch is turned off. When a certain amount of time has elapsed after turning the ignition 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 91

1. While the engine is running, the ECM monitors the synchronization of the soak timer and the CPU clock. If these two are not synchronized, the ECM interprets this as a malfunction, illuminates the MIL and stores the DTC.
2. If the soak timer activates the ECM even though only a short amount of time has elapsed since the ignition 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 ignition switch was turned off, the ECM determines that the soak timer is malfunctioning, illuminates the MIL and stores a DTC the next time the ignition switch is turned ON.

HINT

1. Refer to DTC P2195. Refer to «DESCRIPTION»(ref-394778-S21856657102011040800000).
2. 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 ECM 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 10 seconds after preconditions are met in order to measure the air fuel ratio sensor response rate. During active air fuel ratio control, the ECM 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 ECM 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 ECM interprets this as a malfunction and stores the DTC.

Scheme 92

The Transmission Control Module (TCM) and ECM perform 2-way communication with each other via the Controller Area Network (CAN). The TCM sends signals to the ECM concerning required engine speed, required engine torque, warning indicators in the combination meter, DTCs and other data. The ECM sends signals to the TCM concerning engine speed, opening angle of the throttle valve, temperature of intake air, temperature of engine coolant, engine torque and other data. If the TCM cannot communicate with the ECM, the TCM will conclude that there is a malfunction in the CAN system, illuminate the MIL and set a DTC.

When the ignition switch is turned to ON, the battery voltage is applied to IGSW of the ECM. The output signal from the MREL terminal of the ECM causes a current to flow to the coil, closing the contact of the engine room junction block assembly (EFI MAIN relay) and supplying power to terminals +B and +B2 of the ECM.

Scheme 93

Scheme 94

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

Scheme 95

When the VC circuit is short-circuited, the microprocessor in the ECM and sensors that are supplied with 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 ignition switch is first turned to ON. The MIL turns off when the engine is started.

Scheme 96

Scheme 97

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

Scheme 98

Scheme 99

1. w/o Smart Key System While the engine is being cranked, current flows from terminal ST1 of the ignition switch assembly to the park/neutral position switch assembly and also flows to terminal STA of the ECM (STA Signal).
2. w/ Smart Key System While the engine is being cranked, current flows from terminal STAR of the power management control ECU to the park/neutral position switch assembly and also flows to terminal STA of the ECM (STA signal).

This circuit opens and closes the Intake Air Control Valve (IACV) in response to the engine load in order to increase the intake efficiency (ACIS: Acoustic Control Induction System).

Scheme 100

Scheme 101

The MIL (Malfunction Indicator Lamp) is used to indicate vehicle malfunctions detected by the ECM. By turning the ignition switch to ON, power is supplied to the MIL circuit, and the ECM provides the circuit ground which illuminates the MIL.

The MIL operation can be checked visually. When the ignition switch is first turned to ON, the MIL should be illuminated and should then turn off. If the MIL remains illuminated or is not illuminated, conduct the following troubleshooting procedure. If the ECM detects any trouble, the MIL illuminates. At this time, the ECM records a DTC in the memory.

Scheme 102

Scheme 103

Scheme 104

1. CHECK THAT MIL ILLUMINATES Turn the ignition switch to ON. Check the illumination of the MIL. Result Result Proceed to MIL remains illuminated (Even after ignition switch is turned to ON 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 --> See step 8 B --> See step 5 A: Go to next step
2. CHECK WHETHER MIL TURNS OFF Connect the Techstream to the DLC3. Turn the ignition switch to ON. Turn the Techstream on. Enter the following menus: Powertrain / Engine / Trouble Codes. Check if any DTCs have been stored. Note any DTCs. Clear the DTCs. Refer to «DTC CHECK / CLEAR»(ref-394618-S22943830982011040800000). Check if the MIL goes off. Result Result Proceed to MIL goes off A MIL does not go off B B --> See step 3 A --> See step 9
3. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT IN WIRE HARNESS) Disconnect the ECM connector. Turn the ignition switch to ON. Check if the MIL is illuminated. Result Result Proceed to MIL is not illuminated A MIL is illuminated B TEXT IN ILLUSTRATION *1 Front view of wire harness connector (to ECM) Reconnect the ECM connector. B --> See step 4 A --> See step 10
4. CHECK HARNESS AND CONNECTOR (ACCESSORY METER ASSEMBLY - ECM) Disconnect the accessory meter assembly connector. Disconnect the ECM connector. Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Short) Tester Connection Condition Specified Condition F2-10 (CHK) or A49-36 (W) - Body ground Always 10 kohms or higher Reconnect the accessory meter assembly connector. Reconnect the ECM connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (ACCESSORY METER ASSEMBLY - ECM) OK --> See step 11
5. CHECK IF ENGINE STARTS Start the engine. Result Result Proceed to Engine starts A Engine does not start* B HINT: *: The Techstream cannot communicate with the ECM. B --> See step 12 A: Go to next step
6. CHECK HARNESS AND CONNECTOR (ECM TERMINAL VOLTAGE) Disconnect the ECM connector. Turn the ignition switch to ON. Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Switch Condition Specified Condition A49-36 (W) - Body ground Ignition switch ON 11 to 14 V Reconnect the ECM connector. NG --> See step 7 OK --> See step 10
7. CHECK HARNESS AND CONNECTOR (ACCESSORY METER ASSEMBLY - ECM) Disconnect the accessory meter assembly connector. Disconnect the ECM connector. Measure the resistance according to the value(s) in the table below. Standard Resistance (Check for Open) Tester Connection Condition Specified Condition F2-10 (CHK) - A49-36 (W) Always Below 1 ohms Reconnect the ECM connector. Reconnect the accessory meter assembly connector. NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (ACCESSORY METER ASSEMBLY - ECM) OK --> See step 13
8. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-394618-S11141036502011040800000)
9. REPAIR CIRCUIT INDICATED BY OUTPUT DTC. Refer to «DIAGNOSTIC TROUBLE CODE CHART»(ref-394618-S20895286482011040800000)
10. REPLACE ECM. Refer to «REMOVAL»(ref-394781-S33405130152011040800000)
11. REPLACE ACCESSORY METER ASSEMBLY. Refer to «REMOVAL»(ref-394795-S03061166282011040800000)
12. GO TO VC OUTPUT CIRCUIT. Refer to «VC Output Circuit»(ref-394778-S34666394892011040800000)
13. REPLACE ACCESSORY METER ASSEMBLY. Refer to «REMOVAL»(ref-394795-S03061166282011040800000)

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