Engine Control System (Diagnostic Codes (P0504-U0101) & Circuit Tests)): Overview Scion tC II

DESCRIPTION

The stop light switch is a duplex system that transmits two signals: STP and ST1-. These two signals are used by the ECM to monitor whether or not the brake system is working properly. If 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, the Data List items Stop Light Switch and ST1 are both ON when the brake pedal is depressed because the characteristics of ST1 indication are the opposite of the characteristics of Stop Light Switch indication.

Scheme 95

The idling speed is controlled by the ETCS (Electronic Throttle Control System). The ETCS is comprised of: 1) a 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 ETCS. Based on the target idling speed, the ECM controls the throttle actuator to provide the proper throttle valve opening angle.

MONITOR DESCRIPTION

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

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 10 km/h (6.25 mph) 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.

Scheme 96

This monitor will run when the engine is started with the engine coolant temperature between -10 and 50°C (14 and 122°F). The DTC will be stored after the engine idles for 13 seconds (2 trip detection logic).

The DTC is designed to monitor the idle air control at cold start. When the engine is started with the engine coolant temperature below 50°C (122°F), the ECM measures the accumulated mass air flow while the engine is idling. If it does not reach the threshold 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 ETCS (Electronic Throttle Control System) controls the idle speed. The ETCS 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 ISC (Idle Speed Control) learned values are cleared. This DTC cannot be stored with the ISC learned values cleared.

HINT

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

Scheme 97

This monitor will run when the engine is started at an engine coolant temperature of -10 to 50°C (14 to 122°F). The DTC will be stored after the engine idles for 13 seconds (2 trip detection logic).

The DTC is designed to monitor the 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 ISC (Idle Speed Control) learned values are cleared. This DTC cannot be stored with the ISC learned values cleared.

HINT

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

Scheme 98

The battery supplies electricity to the ECM even when the ignition switch is off. This power allows the ECM to store data such as DTC history, freeze frame data and fuel trim values. If the battery voltage falls below a minimum level, the memory is cleared and the ECM determines that there is a malfunction in the power supply circuit. When the engine is next started, the ECM illuminates the MIL and stores the DTC.

HINT

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

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

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 deviate, a DTC is stored.

The ECM monitors the input signals of the throttle position sensor No. 1 and stop light switch. If the input signals and control signals deviate, a DTC is stored.

While the engine is being cranked, the positive 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 20 km/h (12.4 mph) for over 20 seconds.

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

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

DTC P0630 is stored when the Vehicle Identification Number (VIN) is not stored in the ECM or the input VIN is incorrect. The VIN is input 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 will illuminate the MIL and store a DTC when the ignition switch is turned to ON.

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

This DTC indicates a problem with the park/neutral position switch and the wire harness in the park/neutral position switch circuit.

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

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

The park/neutral position switch sends a signal to the ECM according to the shift position (P, R, N, D, M 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 stop light switch is part of 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. This DTC indicates that the stop light switch remains on. When the stop light switch remains on during GO and STOP driving, the ECM interprets this as a fault in the stop light switch. Then the MIL illuminates and the ECM stores the DTC.

This DTC indicates that the stop light switch remains on. When the stop light switch remains on during GO and STOP driving, the ECM interprets this as a fault in the stop light switch. Then the MIL illuminates and the ECM stores the DTC. The vehicle must GO (30 km/h (18.63 mph) or more) and STOP (less than 3 km/h (1.86 mph)) 5 times for 2 driving cycles in order for the DTC to be stored.

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 will illuminate the MIL and store a DTC immediately.

The Tumble Control Valve (TCV) is built into the intake manifold. The intake air control valve actuator (for TCV) is composed of a position sensor and a DC motor. The DC motor opens and closes the TCV 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

When P2004 and/or P2006 is output, use the Techstream to confirm 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° or more for 10 seconds, DTC P2004 is stored. When the ECM has requested a tumble control valve "open" operation but the actual tumble control valve opening angle is less than 35° for 10 seconds, DTC P2006 is stored.

The ECM activates the DC motor for the intake air control valve actuator (for TCV), which opens and closes the Tumble Control Valve (TCV). 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 stores a DTC.

The Tumble Control Valve (TCV) position sensor is a non-contact type sensor.

The position sensor measures the opening angle of the TCV. The sensor is reliable and accurate, as it is electrically controlled by Hall-effect elements.

Scheme 99

HINT

When DTC P2014, P2016 or P2017 is output, use the Techstream to confirm the IAC Sensor Voltage (TCV position sensor output voltage). Enter the following menus: Powertrain / Engine / Data List / All Data.

The ECM IAC1 terminal voltage increases in correlation with the opening angle of the TCV. When the TCV is fully closed, approximately 0.8 V is applied to the IAC1 terminal. When the TCV 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. Refer to ECM Power Source Circuit. Refer to ECM Power Source Circuit.

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 ETCS (Electronic Throttle Control System) 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, if the throttle actuator is stuck on), the ECM determines that there is a malfunction. The ECM then illuminates the MIL and stores a DTC.

Example

When the electrical current is below 0.5 A and the throttle actuator duty ratio is 80% or more, 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 engine speed several times after the engine is started and has idled for 5 seconds.

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 so that the ECM can control the throttle actuator (throttle valve) appropriately in response to driver inputs.

HINT

This ETCS (Electronic Throttle Control System) 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 ETCS (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 ETCS and cuts off the current to the throttle actuator.

When the voltage becomes unstable, the ETCS 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 current to flow to the throttle actuator so that it can be restarted.

HINT

The ETCS does not use a throttle cable.

Scheme 100

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 (ETCS) 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 calculated by the ECM. If the difference between these two values is outside the standard range, the ECM interprets this as a malfunction in the ETCS. 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 the accelerator pedal being fully depressed (fully opening the throttle valve).

The accelerator pedal position 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 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 depending on the position of the accelerator pedal (throttle valve). The signal from VPA indicates the actual accelerator pedal position (throttle valve opening angle) and is used for engine control. The signal from VPA2 conveys the status of the VPA circuit and is used to check the accelerator pedal position sensor itself.

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

HINT

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

Scheme 101

HINT

When any of these DTCs is stored, check the accelerator pedal position sensor voltage by entering 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 the output voltage of either VPA or VPA2 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

Refer to DTC P2120. Refer to DESCRIPTION.

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.

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 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 of the planar type and is 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), a current flows through the heater to heat the sensor in order to facilitate accurate air-fuel ratio 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, thereby accelerating the sensor activation.

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 (TWC) is used. For the most efficient use of the Three-Way Catalytic Converter (TWC), the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric level.

*: The 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 102

HINT

1. When either of these DTCs is stored, check the air fuel ratio sensor output voltage by entering the following menus: Powertrain / Engine / Data List / All Data / AFS Voltage B1S1.
2. Short-term fuel trim values can also be read using the Techstream.
3. The ECM maintains the voltages at the A1A+ and A1A- terminals of the ECM at a constant level. Therefore, the air fuel ratio sensor output voltage cannot be confirmed without using the Techstream.
4. If the air fuel ratio sensor is malfunctioning, the ECM stores DTC P2195 or P2196.

Sensor voltage detection monitor

Under air-fuel ratio feedback control, if the air fuel ratio sensor output voltage is below 2.8 V (very rich condition) for 5 seconds despite the rear heated oxygen sensor output voltage being below 0.59 V, the ECM stores DTC P2196. Alternatively, if the air fuel ratio sensor output voltage is higher than 3.8 V (very lean condition) for 5 seconds despite the rear heated oxygen sensor output voltage being 0.21 V or higher, 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 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 (stuck on high side). If the air fuel ratio sensor output is below 0.7 mA for more than 3 seconds of cumulative time, the ECM stores DTC P2196 (stuck on low side).

Scheme 103

Refer to P0300. Refer to DESCRIPTION.

Refer to P2195. Refer to DTC P2195: Oxygen (A/F) Sensor Signal Stuck Lean (Bank 1 Sensor 1); DTC P2196: Oxygen (A/F) Sensor Signal Stuck Rich (Bank 1 Sensor 1).

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 a problem is present and stores a DTC.

A/F Sensor Monitoring Method

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 system determines that there is a problem.

Crankshaft Position Sensor Monitoring Method

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

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 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 outside of the specified range, or the admittance is below the standard value, the ECM will determine that there is a malfunction in the air fuel ratio sensor. If the same malfunction is detected in the next driving cycle, the MIL is illuminated and a DTC is stored.

The air fuel ratio sensor varies its output voltage in proportion to the air-fuel ratio. If the air fuel ratio sensor impedance (alternating current resistance) or output voltage deviates greatly from the standard range, the ECM determines that there is an open or short in the air fuel ratio sensor circuit.

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 104

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 105

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 106

1. While the engine is running, the ECM monitors the synchronization of the soak timer and 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 to ON.

The ECM (engine control unit) communicates with the TCM (transmission control ECU) through the Controller Area Network (CAN).

If there is a problem with this communication, the ECM stores a DTC.

When the ignition switch is turned to ON, the battery voltage is applied to the IGSW terminal of the ECM. The output signal from the MREL terminal of the ECM causes a current to flow to the coil of the integration relay (EFI NO. 1 relay), closing the contacts and supplying power to terminals +B and +B2 of the ECM.

Scheme 107

The ECM constantly generates a 5 V power source voltage from the battery voltage 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 108

When the VC circuit is short-circuited, the microprocessor in the ECM and the sensors that are supplied with power through the VC circuit are inactivated because 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 goes off when the engine is started.

Scheme 109

Scheme 110

Scheme 111

1. CHECK MIL Check that the Malfunction Indicator Lamp (MIL) lights up when the ignition switch is turned to ON. OK MIL lights up. NG --> See step 2 OK --> See step 17
2. CHECK COMMUNICATION BETWEEN TECHSTREAM AND ECM Connect the Techstream to the DLC3. Turn the ignition switch to ON. Turn the Techstream on. Check the communication between the Techstream and ECM. RESULT Result Proceed to Communication is possible A Communication is not possible B A --> See step 10 B: Go to next step
3. CHECK MIL (THROTTLE POSITION SENSOR) Disconnect the throttle with motor body connector. Turn the ignition switch to ON. Check the MIL. RESULT Result Proceed to MIL illuminates A MIL does not illuminate B A --> See step 11 B: Go to next step
4. CHECK MIL (ACCELERATOR PEDAL POSITION SENSOR) Disconnect the accelerator pedal position sensor connector. Turn the ignition switch to ON. Check the MIL. RESULT Result Proceed to MIL illuminates A MIL does not illuminate B A --> See step 12 B: Go to next step
5. CHECK MIL (CANISTER PUMP MODULE) Disconnect the canister connector. Turn the ignition switch to ON. Check the MIL. RESULT Result Proceed to MIL illuminates A MIL does not illuminate B A --> See step 13 B: Go to next step
6. CHECK MIL (INTAKE AIR CONTROL VALVE ACTUATOR (FOR TCV)) Disconnect the intake air control valve actuator (for TCV) connector. Turn the ignition switch to ON. Check the MIL. RESULT Result Proceed to MIL illuminates A MIL does not illuminate B A --> See step 14 B: Go to next step
7. CHECK MIL (CAMSHAFT POSITION SENSOR FOR INTAKE SIDE) Disconnect the camshaft position sensor (for Intake Side) connector. Turn the ignition switch to ON. Check the MIL. RESULT Result Proceed to MIL illuminates A MIL does not illuminate B A --> See step 15 B: Go to next step
8. CHECK MIL (CAMSHAFT POSITION SENSOR FOR EXHAUST SIDE) Disconnect the camshaft position sensor (for Exhaust Side) connector. Turn the ignition switch to ON. Check the MIL. RESULT Result Proceed to MIL illuminates A MIL does not illuminate B A --> See step 16 B: Go to next step
9. CHECK HARNESS AND CONNECTOR Disconnect the throttle with motor body connector. Disconnect the accelerator pedal position sensor connector. Disconnect the canister pump module connector. Disconnect the intake air control valve actuator (for TCV) connector. Disconnect the camshaft position sensor (for Intake Side) connector. Disconnect the camshaft position sensor (for Exhaust Side) connector. Disconnect the ECM connectors. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition B30-88 (VCTA) - Body ground Always 10 kohms or higher A35-57 (VCPA) - Body ground Always 10 kohms or higher A35-58 (VCP2) - Body ground Always 10 kohms or higher B30-72 (VCIA) - Body ground Always 10 kohms or higher B30-113 (VCPP) - Body ground Always 10 kohms or higher B30-98 (VCE1) - Body ground Always 10 kohms or higher B30-99 (VCV1) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 18
10. GO TO MIL CIRCUIT. Refer to «MIL Circuit»(ref-451172-S41623247702012020700000)
11. REPLACE THROTTLE WITH MOTOR BODY ASSEMBLY. Refer to «REMOVAL»(ref-451166-S06090055942012020700000)
12. REPLACE ACCELERATOR PEDAL POSITION SENSOR ASSEMBLY. Refer to «REMOVAL»(ref-451166-S40840052852012020700000)
13. REPLACE CANISTER. Refer to «REMOVAL»(ref-451182-S29111003172012020700000)
14. REPLACE INTAKE AIR CONTROL VALVE ACTUATOR (FOR TCV). Refer to «REMOVAL»(/scion/tc/ii-2010-2013/remont/exhaust/#intake-system-exhaust-system-service-information)
15. REPLACE CAMSHAFT POSITION SENSOR (FOR INTAKE SIDE). Refer to «REMOVAL»(ref-451166-S11972717362012020700000)
16. REPLACE CAMSHAFT POSITION SENSOR (FOR EXHAUST SIDE). Refer to «REMOVAL»(ref-451166-S11972717362012020700000)
17. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-451061-S17066097812012020700000)
18. REPLACE ECM. Refer to «REMOVAL»(ref-451166-S22630148492012020700000)

When the engine is cranked, the starter relay drive signal output from the ignition switch*1 or power management control ECU*2 is input into the STA terminal of the ECM, and the NE signal generated by the crankshaft position sensor is input into the NE+ terminal. The ECM determines that the engine is cranked, and turns transistor Tr1 in the ECM internal circuit on. Current flows to the C/OPN (Circuit Opening) relay by turning Tr1 on.

Then, the fuel pump operates.

While the NE signal is input into the ECM and the engine is running, the ECM turns Tr1 on continuously.

*1: w/o Smart Key System

*2: w/ Smart Key System

Scheme 112

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

Scheme 113

While the engine is being cranked, current flows from terminal ST1 of the ignition switch*1 or terminal STAR of the power management control ECU*2 to the park/neutral position switch (for A/T) or clutch pedal switch (for M/T) and also flows to terminal STA of the ECM (STA signal).

1. *1: w/o Smart Key System
2. *2: w/ Smart Key System

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

Scheme 114

Scheme 115

When the vehicle is being driven with the accelerator pedal depressed, depressing the brake pedal without releasing the accelerator pedal will activate the brake override system to restrict driving torque. The conditions for activating the brake override system as well as the items that are controlled are explained below.

Scheme 116

Activation Conditions

1. Vehicle is running at or above a specified speed.
2. The accelerator pedal is depressed beyond a specified level, and then the brake pedal is depressed.

Note. The vehicle may not enter brake override system control due to the relation of the accelerator pedal angle and the vehicle's speed.

Items Controlled

1. Driving torque is restricted.

HINT

During brake override system control, the value for the accelerator pedal angle (which is used for engine control) is forcibly reduced to a specified value. For this reason, the Data List value for Accelerator Position (applied to electronic throttle control) will be replaced with a specified value regardless of the actual accelerator pedal angle (Accel Sens. No. 1 Volt %, Accel Sens. No. 2 Volt %).

Deactivation Conditions

1. When the stop light switch turns off or the actual accelerator pedal angle increases or decreases beyond the specified range.

The MIL (Malfunction Indicator Lamp) is used to indicate the detection of vehicle malfunctions by the ECM. When the ignition switch is turned 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 when the engine is started. If the MIL remains illuminated or is not illuminated, conduct the following troubleshooting procedure using the Techstream.

Scheme 117

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