Engine Control System (Diagnostic Codes (P1604-U0101) & Circuit Tests)) (2AR-FE): Overview Toyota Camry XV50

DESCRIPTION

This DTC is stored when the engine does not start even though the STA signal is input or when the engine takes a long time to start, and when the engine speed is low or the engine stalls just after the engine starts.

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 there is engine starting trouble due to running out of fuel.

Scheme 87

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Scheme 89

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 starting difficulty FREEZE FRAME DATA P1604 STARTABILITY MALFUNCTION Parameter -3 -2 -1 0 1 Unit Engine Speed 398 325 221 159 114 rpm Calculate Load 43.1 42.7 43.1 87.4 87.4 % Vehicle Load 28.2 26.2 26.6 17.2 15.0 % MAF 3.01 2.28 1.59 0.75 0.48 gm/sec Atmosphere Pressure 14.5 14.5 14.5 14.5 14.5 psi (gauge) Coolant Temp 185 185 185 185 185 F Intake Air 115 115 115 115 115 F Battery Voltage 12.460 12.382 12.324 12.324 12.343 V Throttle Sensor Volt % 16.4 16.0 17.6 16.0 16.0 % Throttle Sensor #2 Volt % 48.6 47.8 49.8 47.8 47.8 % Throttle Sensor Position 0.0 0.0 0.0 0.0 0.0 % Throttle Motor DUTY 17.6 16.0 16.0 16.0 16.0 % Injector (Port) 4240 4302 4612 4612 7776 μs Injection Volume (Cylinder 1) 0.274 0.274 0.187 0.187 0.187 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 0.864 0.873 0.882 0.883 0.830 AF Lambda B1S1 0.999 0.999 1.001 1.002 1.005 AFS Voltage B1S1 3.298 3.298 3.307 3.312 3.327 V O2S B1S2 0.015 0.015 0.015 0.015 0.015 V Short FT #1 0.000 0.000 0.000 0.000 0.000 % 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 OL OL OL OL OL IGN Advance 8.0 7.0 6.0 0.0 0.0 deg Knock Feedback Value -3.0 -3.0 -3.0 -3.0 -3.0 °CA Knock Correct Learn Value 19.0 19.0 19.0 19.0 19.0 °CA VVT Control Status #1 OFF OFF OFF OFF OFF Starter Signal Close Close Close Close Close

MONITOR DESCRIPTION

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 the DTC immediately.

The Tumble Control Valve (TCV) is built into the intake manifold. The intake air control valve actuator (for 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

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: WHEN ENGINE WARMED UP)

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 stored. 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 stored.

The ECM activates the intake air control valve actuator (for tumble control valve), 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 intake air control valve actuator 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 tumble control valve. The sensor is reliable and accurate, as it is electrically controlled by Hall-effect elements.

Scheme 90

HINT

When DTC P2014, P2016 or P2017 is output, use the Techstream to confirm the IAC Sensor Voltage (tumble control valve position sensor output voltage). Enter the following menus: Powertrain / Engine and ECT / Data List / Gas Intake Control / 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 0.94 V is applied to the IAC1 terminal. When the tumble control valve is fully open, approximately 3.4 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 with motor body assembly. The throttle position sensor provides feedback to the ECM. This feedback allows the ECM to appropriately control the throttle actuator and monitor the throttle opening angle as the ECM responds to driver inputs.

HINT

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

The ECM 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 less than 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.

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

HINT

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

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

1. 1) The mass air flow meter sub-assembly is normal.
2. 2) Atmospheric pressure is 85 kPa(abs) [638 mmHg(abs)] or higher.
3. 3) The vehicle has been driven at a speed of 30 km/h (18.6 mph) or more at least once.
4. 4) The engine coolant temperature is 45°C (113°F) or less at engine start, the engine is warmed up and conditions for ISC learning are met, or the ignition switch has been turned to ON (include engine running) for 1 hour or more, the engine is warmed up and conditions for ISC learning are met.

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

HINT

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

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

The electronic throttle control system has a dedicated power supply circuit. The voltage (+BM) is monitored and when it is low (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 91

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

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

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

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

HINT

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

The accelerator pedal position sensor is built into the accelerator pedal sensor assembly 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 opening 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 position sensor itself.

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

Scheme 92

HINT

When any of these DTCs are output, check the accelerator pedal position sensor voltage using the Techstream. Enter the following menus: Powertrain / Engine and ECT / Data List / Gas Throttle / 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 VPA2 deviates from the standard range, or the difference between the output voltages of the 2 sensor circuits is more 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 is less than 0.4 V for more than 0.5 seconds when the accelerator pedal is fully depressed, DTC P2122 is stored.

HINT

This DTC relates to the accelerator pedal position sensor.

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 illuminates 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 duration. If the air fuel ratio sensor malfunctions, the ECM is unable to control the air fuel ratio accurately.

The air fuel ratio sensor is a planar type and 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 a narrow type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, and therefore sensor activation is accelerated.

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

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

Scheme 93

HINT

1. When any of these DTCs is stored, check the air fuel ratio sensor voltage output by entering the following menus on the Techstream: Powertrain / Engine and ECT / Data List / Gas AF Control / AFS Voltage B1S1.
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 stores a DTC.

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 heated oxygen sensor output voltage being below 0.69 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 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 94

Refer to DTC P0300. Refer to DESCRIPTION.

Refer to DTC P2195. Refer to DESCRIPTION.

Fuel System Air Fuel Ratio Cylinder Imbalance Monitor

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

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

Air Fuel Ratio 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.

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.
3. Refer to DTC P2195. Refer to «DESCRIPTION»(ref-507926-S04049479602012100900000).

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 (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.

Scheme 95

TEXT IN ILLUSTRATION

P2420: Vent valve stuck open (vent)

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

Scheme 96

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 97

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-507926-S04049479602012100900000).
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 98

The Engine Control Module (ECM) communicates with the Transmission Control Module (TCM) through the Controller Area Network (CAN).

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

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

Scheme 99

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 100

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 101

Scheme 102

When the engine is cranked, the ST (Starter) relay drive signal output from the ignition switch assembly*1 or certification ECU (smart key ECU assembly)*2 is input to the STA terminal of the ECM, and the NE signal generated by the crankshaft position sensor is also input to the NE+ terminal. Thus, the ECM interprets that the engine has been 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 to the ECM with the engine running, the ECM turns Tr1 on continuously.

1. *1: w/o smart key system.
2. *2: w/ smart key system.

Scheme 103

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

Scheme 104

While the engine is being cranked, current flows from terminal ST1 of the ignition switch assembly*1 or terminal STAR of the certification ECU (smart key ECU assembly)*2 to the park/neutral position switch and to terminal STA of the ECM (STA signal).

1. *1: w/o smart key system
2. *2: w/ smart key system

Scheme 105

Scheme 106

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 107

Scheme 108

When the vehicle is being driven, depressing the accelerator pedal sensor assembly and brake 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 109

Activation Conditions

1. Vehicle is running at or above the specified speed.
2. When the accelerator pedal and brake pedal are depressed.

Note. The vehicle may not enter the 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 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 brake pedal or the accelerator pedal returns to some degree.

The MIL (Malfunction Indicator Lamp) is used to indicate vehicle malfunctions detected 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 turned to ON, the MIL should be illuminated and should turn off after engine is started. If the MIL remains illuminated or is not illuminated, conduct the following troubleshooting procedure using the Techstream.

Scheme 110

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