Engine Control System (Diagnostic Codes (P1604-U0101) & Circuit Tests): Overview Lexus ES XV60

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 44

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1. Reference waveforms showing a normal cold engine start
2. Reference waveforms showing a normal warm engine start
3. Reference values when there is an air leak in the intake system during starting difficulty FREEZE FRAME DATA P1604 STARTABILITY MALFUNCTION Parameter -3 -2 -1 0 1 Unit Engine Speed 1489 986 345 186 124 rpm Calculate Load 36.2 28.2 31.4 92.4 94.6 % Vehicle Load 7.9 7.9 9.2 7.2 6.0 % MAF 10.12 5.04 2.79 0.81 0.68 gm/sec Atmosphere Pressure 0 0 0 0 0 kPa Coolant Temp 185 185 185 185 185 F Intake Air 102 102 102 102 102 F Battery Voltage 13.222 13.300 12.109 11.972 11.854 V Throttle Sensor Volt % 16.5 16.5 16.0 15.6 15.6 % Throttl Sensor #2 Volt % 48.2 48.2 47.8 47.2 47.2 % Throttle Sensor Position 0.0 0.0 0.0 0.0 0.0 % Throttle Motor DUTY 16.5 16.5 16.0 15.6 15.6 % Injector (Port) 3628 2620 2744 2744 2744 μs Injection Volum (Cylinder 1) 3.062 0.226 0.226 0.226 0.226 ml Fuel Pump Duty 58.6 58.6 58.6 58.6 58.6 % 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 System Vent Valve OFF OFF OFF OFF OFF EVAP Purge VSV OFF OFF OFF OFF OFF Purge Cut VSV Duty 0.0 0.0 0.0 0.0 0.0 % Target Air-Fuel Ratio 0.998 0.998 0.998 0.998 0.998 AF Lambda B1S1 0.999 0.999 0.999 0.999 0.999 AF Lambda B2S1 0.997 0.997 0.997 0.998 0.998 AFS Voltage B1S1 3.258 3.258 3.258 3.258 3.258 V AFS Voltage B2S1 3.251 3.251 3.251 3.253 3.253 V O2S B1S2 0.000 0.000 0.000 0.000 0.000 V O2S B2S2 0.015 0.015 0.015 0.000 0.000 V Short FT #1 0.000 0.000 0.000 0.000 0.000 % Long FT #1 8.782 4.354 -2.665 -2.665 -2.665 % Total FT #1 0.058 0.058 0.058 0.058 0.058 Sort FT #2 0.000 0.000 0.000 0.000 0.000 % Long FT #2 9.264 4.587 -2.462 -2.462 -2.462 % Total FT #2 0.062 0.062 0.062 0.062 0.062 Fuel System Status #1 OL OL OL OL OL Fuel System Status #2 OL OL OL OL OL IGN Advance 0.0 10.5 16.5 18.0 18.0 deg Knock Feedback Value -1.5 -1.5 -1.5 -1.5 -1.5 deg(CA) Knock Correct Learn Value 17.0 17.0 17.0 17.0 17.0 deg(CA) Starter Signal OFF OFF OFF OFF OFF

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 stores DTC immediately.

The throttle actuator is operated by the ECM and opens and closes the throttle valve using gears.

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

HINT

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

The ECM monitors the electrical current through the electronic actuator, and detects malfunctions and open circuits in the throttle actuator based on this value. If the current is outside the standard range, the ECM determines that there is a malfunction in the throttle actuator. In addition, if the throttle valve does not function properly (for example, stuck on), the ECM determines that there is a malfunction. The ECM then illuminates the MIL and stores a DTC.

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

HINT

1. The ISC learned value is the calculated intake air amount corresponding to the throttle opening amount necessary to maintain the 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 body with motor assembly and mass air flow meter sub-assembly to detect this malfunction.

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

1. 1) The mass air flow meter sub-assembly is normal.
2. 2) Atmospheric pressure is 85 kPa(abs) [637.5 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 engine switch has been turned on (IG) (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 body with motor assembly. The throttle position sensor provides feedback to the ECM. This feedback allows the ECM to appropriately control the throttle actuator and monitor the throttle opening angle as the ECM responds to driver inputs.

HINT

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

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

The electronic throttle control system has a dedicated power supply circuit. The voltage (+BM) is monitored and when it is low (less than 4 V), the ECM determines that there is a malfunction in the electronic throttle control system and cuts off the current to the throttle actuator.

When the voltage becomes unstable, the electronic throttle control system itself becomes unstable. For this reason, when the voltage is low, the current to the throttle actuator is cut. If repairs are made and the system returns to normal, turn the engine 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 47

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 4.75 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 48

HINT

When any of these DTCs are output, check the accelerator pedal position sensor voltage using the Techstream. Enter the following menus: Powertrain / Engine / 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

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

The air fuel ratio sensor generates voltage* that corresponds to the actual air fuel ratio. This sensor voltage is used to provide the ECM with feedback so that it can control the air fuel ratio. The ECM determines the deviation from the stoichiometric air fuel ratio level, and regulates the fuel injection 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 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, 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 49

HINT

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

Sensor Voltage Detection Monitor

Under air fuel ratio feedback control, If the air fuel ratio sensor output voltage is less than 2.8 V (very rich condition) for 5 seconds despite the heated oxygen sensor output voltage being less than 0.59 V, the ECM stores DTC P2196 or P2198. Alternatively, if the air fuel ratio sensor output voltage is higher than 3.8 V (very lean condition) for 5 seconds despite the heated oxygen sensor output voltage being 0.21 V or higher, DTC P2195 or P2197 is stored.

Sensor Current Detection Monitor

A rich air fuel mixture causes a low air fuel ratio sensor current, and a lean air fuel mixture causes a high air fuel ratio sensor current. Therefore, the sensor output becomes low during acceleration, and it becomes high during deceleration with the throttle valve fully closed. The ECM monitors the air fuel ratio sensor current during fuel-cut and detects any abnormal current values.

If the air fuel ratio sensor output is 2.2 mA or more for more than 3 seconds of cumulative time, the ECM interprets this as a malfunction in the air fuel ratio sensor and stores DTC P2195 or P2197 (stuck on high side). If the air fuel ratio sensor output is less than 0.8 mA for more than 3 seconds of cumulative time, the ECM stores DTC P2196 or P2198 (stuck on low side).

Scheme 50

Refer to DTC P0300. Refer to DESCRIPTION .

Refer to DTC P2195, P2197. Refer to DESCRIPTION .

Fuel System Air Fuel Ratio Cylinder Imbalance Monitor

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

When the air fuel ratios of the cylinders are lean or rich with respect to each other, the ECM determines that 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.

Refer to DTC P2195. Refer to DESCRIPTION .

HINT

1. DTCs P2237, P2238, P2239, P2252 and P2253 indicate malfunctions related to the bank 1 air fuel ratio sensor circuit.
2. DTCs P2240, P2241, P2242, P2255 and P2256 indicate malfunctions related to the bank 2 air fuel ratio sensor circuit.

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 engine switch on (IG), and the admittance (admittance is an electrical term that indicates the ease of flow of current) is checked while driving. If the voltage of the air fuel ratio sensor is between 0.5 V and 4.5 V, it is considered normal. If the voltage is out of the specified range, or the admittance is less than the standard value, the ECM determines that there is a malfunction in the air fuel ratio sensor. If the same malfunction is detected in 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 engine 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 less than 35°C (95°F) 5 hours after the engine switch is turned off, the monitor check starts 2 hours later. If it is still not less than 35°C (95°F) 7 hours after the engine 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 51

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 52

The soak timer operates after the engine switch is turned off. When a certain amount of time has elapsed after turning the engine 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 53

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 engine 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 engine switch was turned off, the ECM determines that the soak timer is malfunctioning, illuminates the MIL and stores a DTC the next time the engine switch is turned on (IG).

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 assembly, 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 store a DTC.

LOCATION

Scheme 54

TEXT IN ILLUSTRATION

The active control engine mount system decreases engine vibration at a low engine speed using the duty vacuum switching valve (for active control engine mount). The duty vacuum switching valve (for active control engine mount) is controlled by a pulse signal transmitted to the duty vacuum switching valve (for active control engine mount) from the ECM. The frequency of this pulse signal is matched to the engine speed to decrease engine vibration.

Scheme 55

When the engine switch is turned on (IG), 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 contact and supplying power to terminals +B and +B2 of the ECM.

Scheme 56

The ECM constantly generates 5 V power source voltage from the battery voltages 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 57

When the VC circuit is short-circuited, the microprocessor in the ECM and sensors that are supplied with power through the VC circuit are deactivated because the power is not supplied from the VC circuit. Under this condition, the system does not start up and the MIL does not illuminate even if the system malfunctions.

HINT

Under normal conditions, the MIL is illuminated when the engine switch is turned on (IG). The MIL goes off when the engine is started.

Scheme 58

Scheme 59

The fuel pump circuit consists of the ECM, fuel pump and fuel pump control ECU assembly (which operates the fuel pump). Based on the engine output, the ECM determines the fuel pump speed. The speed is then converted to a duty signal and sent to the fuel pump control ECU assembly. Based on the signal sent from the ECM, the fuel pump ECU adjust the fuel pump operation speed.

Scheme 60

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

Scheme 61

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

Scheme 62

This circuit opens and closes the intake air control valve assembly (built into intake air surge tank assembly) in response to changes in the engine load in order to increase the intake efficiency using the acoustic control induction system.

When the engine speed is between 0 and 4200 rpm and the throttle valve opening angle is 60° or more, the ECM supplies current to the actuator (on status), to close the intake air control valve assembly. Under other conditions, the intake air control valve assembly is open.

Scheme 63

Scheme 64

The air cleaner is equipped with 2 inlets, one of which is opened or closed by the air intake control valve. This system reduces intake noise and increases engine power at low-to-high engine speed ranges.

When the engine is operating in the low-to-mid speed range, this control operates the air intake control valve to close one of the air cleaner inlets. When the engine speed is higher than 3600 rpm and the opening angle of the throttle valve is more than 60°, the ECM activates the vacuum switching valve (for air intake control valve) and opens the air intake control valve.

Scheme 65

Scheme 66

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 67

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

Scheme 68

See also:
• ON-VEHICLE INSPECTION [06/2012 - ] - Step 2
• ON-VEHICLE INSPECTION [06/2012 - ]
• ON-VEHICLE INSPECTION [06/2012 - ]
• INSPECTION [06/2012 - ]
• REMOVAL [06/2012 - ]
• INSPECTION [06/2012 - ]
• ON-VEHICLE INSPECTION [06/2012 - ]