Engine Control System (Diagnostic Codes ( P0327 - P1422)) (Plug-In): Overview Toyota Prius Plug-in

DESCRIPTION

A flat-type knock control sensor (non-resonant type) has a structure that can detect vibrations between approximately 5 kHz and 15 kHz.

The knock control sensor is fitted onto the engine block to detect engine knocking.

The knock control sensor contains a piezoelectric element which generates a voltage when it becomes deformed.

The voltage is generated when the engine block vibrates due to knocking. Any occurrence of engine knocking can be suppressed by delaying the ignition timing.

HINT

When DTC P0327 or P0328 is stored, the ECM enters fail-safe mode. During fail-safe mode, the ignition timing is delayed to its maximum retardation. Fail-safe mode continues until the power switch is turned off.

Reference: Inspection using an oscilloscope

Scheme 347

HINT

The correct waveform is as shown.

MONITOR DESCRIPTION

If the output voltage transmitted by the knock control sensor remains low or high for 1 second or more, the ECM interprets this as a malfunction in the sensor circuit, and stores a DTC.

The monitor for DTCs P0327 and P0328 begins to run when 5 seconds have elapsed since the engine was started.

The crankshaft position sensor system consists of a No. 1 crankshaft position sensor plate and a pickup coil.

The No. 1 crankshaft position sensor plate has 34 teeth and is installed on the crankshaft. The pickup coil is made of wound copper wire, an iron core and magnet. The No. 1 crankshaft position sensor plate rotates and, as each tooth passes by the pickup coil, a pulse signal is created. The pickup coil generates 34 signals per crankshaft revolution. Based on these signals, the ECM calculates the crankshaft position and engine speed. Using these calculations, the fuel injection and ignition timing are controlled.

Scheme 348

1. Reference: Inspection using an oscilloscope. HINT: The correct waveform is as shown. Grounding failure of the shielded wire may cause noise in the waveforms. ECM Terminal Name Between NE+ and NE- Tester Range 5 V/DIV., 20 ms./DIV. Condition Idling with warm engine

If there is no signal from the crankshaft position sensor despite the crankshaft rotating, the ECM interprets this as a malfunction of the sensor.

The camshaft position sensor for the intake camshaft (G2 signal) consists of a magnet and MRE (Magneto Resistance Element).

The camshaft has a timing rotor for the camshaft position sensor. When the camshaft rotates, changes occur in the air gaps between the timing rotor and MRE, which affects the magnetic field. As a result, the resistance of the MRE material fluctuates. The camshaft position sensor converts the camshaft rotation data to pulse signals, uses the pulse signals to determine the camshaft angle, and sends it to the ECM. Then the ECM uses this data to control fuel injection duration and injection timing.

Scheme 349

1. Reference: Inspection using an oscilloscope. HINT: The correct waveform is as shown. ECM Terminal Name Between G2+ and G2- Tester Range 5 V/DIV., 20 ms./DIV. Condition Idling with warm engine

If no signal is transmitted by the camshaft position sensor despite the engine revolving, or the rotation of the camshaft and the crankshaft is not synchronized, the ECM interprets this as a malfunction of the sensor.

HINT

1. These DTCs indicate malfunctions relating to the primary circuit.
2. If DTC P0351 is output, check the No. 1 ignition coil assembly circuit.
3. If DTC P0352 is output, check the No. 2 ignition coil assembly circuit.
4. If DTC P0353 is output, check the No. 3 ignition coil assembly circuit.
5. If DTC P0354 is output, check the No. 4 ignition coil assembly circuit.

A Direct Ignition System (DIS) is used on this vehicle.

The DIS is a 1-cylinder ignition system in which each cylinder is ignited by one ignition coil assembly and one spark plug is connected to the end of each secondary wiring. A powerful voltage, generated in the secondary wiring, is applied directly to each spark plug. The spark of the spark plugs passes from the center electrode to the ground electrodes.

The ECM determines the ignition timing and transmits the ignition (IGT) signals to each cylinder. Using the IGT signal, the ECM turns the power transistor inside the igniter on and off. The power transistor, in turn, switches the current supplied to the primary coil on and off. When the current to the primary coil is cut off, a powerful voltage is generated in the secondary coil. This voltage is applied to the spark plugs, causing them to spark inside the cylinders. As the ECM cuts the current to the primary coil, the igniter sends back an ignition confirmation (IGF) signal to the ECM for each cylinder ignition.

Scheme 350

Scheme 351

1. Reference: Inspection using an oscilloscope.

HINT

1. The correct waveform is as shown.

1. While idling the engine, check the waveform between terminals IGT (1 to 4) and E1, and IGF1 and E1 of the ECM connector.

Scheme 352

If the ECM does not receive any IGF signals despite transmitting the IGT signal, it interprets this as a fault in the igniter and stores a DTC.

Based on the driving conditions, the ECM regulates the volume of exhaust gas that is recirculated to the engine's combustion chambers and thus lowers the combustion temperature to reduce NOx emissions. The ECM monitors signals such as engine speed, coolant temperature, electric load, and vehicle speed. When the EGR permission conditions are fulfilled, the ECM controls the opening of the EGR valve linearly through signals to the EGR step motor.

The ECM monitors the pressure inside the intake manifold while opening and closing the EGR valve during fuel cut operation. If there is no change in the manifold absolute pressure sensor value, the ECM interprets this as a malfunction in the EGR valve assembly, illuminates the MIL and stores the DTC (2 trip detection logic).

Refer to DTC P0401. Refer to DESCRIPTION.

This DTC is designed to detect an open or short in the EGR valve assembly circuit.

Example

1. If the EGR1, EGR2, EGR3 or EGR4 terminal output voltage is excessively low, but the step motor is still operating, the ECM determines that there is a short in the EGR valve assembly circuit, and stores the DTC.
2. If the EGR1, EGR2, EGR3 or EGR4 terminal output voltage is excessively low, and the step motor is not operating, the ECM determines that there is an open in the EGR valve assembly circuit, and stores the DTC.

The ECM uses sensors mounted in front of and behind the three-way catalytic converter to monitor its efficiency.

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

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

The oxygen storage capacity value is an indication of the oxygen storage capacity of the three-way catalytic converter. When the vehicle is being driven with a warm engine, active air fuel ratio control is performed for approximately 15 to 25 seconds. When it is performed, the ECM deliberately sets the air fuel ratio to lean or rich levels. If the cycle of the waveform for the heated oxygen sensor is long, the oxygen storage capacity is great. There is a direct correlation between the heated oxygen sensor and the oxygen storage capacity of the three-way catalytic converter.

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

This system determines the deterioration of the entire catalyst system (including the front and rear catalysts), by using the oxygen storage capacity value of the front catalyst, that is more sensitive than the rear catalyst, as the representative value. Therefore, be sure to replace the front and rear catalysts together when catalyst replacement is necessary.

Scheme 353

TEXT IN ILLUSTRATION

Note. When replacing the front exhaust pipe assembly (*4) in order to replace the three-way catalytic converter, it is not necessary to replace the heated oxygen sensor (*2).

The description can be found in the EVAP (evaporative emission) System. Refer to DESCRIPTION.

In sequence B and E, the leak detection pump creates negative pressure (vacuum) through the reference orifice. The EVAP system pressure is then measured by the ECM, using the canister pressure sensor, to determine the reference pressure. If the pressure is one of the following conditions, the ECM illuminates the MIL and stores the DTC (2 trip detection logic).

1. EVAP pressure is lower than the malfunction criterion.
2. EVAP pressure is higher than the malfunction criterion.
3. EVAP pressure is not saturated within 60 seconds.
4. EVAP pressure difference between sequence B and E is large.

Scheme 354

Scheme 355

The description can be found in the EVAP (evaporative emission) System. Refer to DESCRIPTION.

The two monitors, Key-off and Purge Flow, are used to detect malfunctions relating to DTC P0441. The key-off monitor is initiated by the ECM internal timer, known as the soak timer, 5 hours* after the power switch is turned off. The purge flow monitor runs while the engine is running.

HINT

*: If the engine coolant temperature is not less than 35°C (95°F) 5 hours after the power 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 power switch is turned off, the monitor check starts 2.5 hours later.

Scheme 356

Scheme 357

Scheme 358

1. KEY-OFF MONITOR Purge VSV stuck open In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP system. The EVAP system pressure is then measured by the ECM using the canister pressure sensor. If the stabilized system pressure is higher than [second reference pressure x 0.2], the ECM interprets this as the purge VSV (Vacuum Switching Valve) being stuck open. The ECM illuminates the MIL and stores the DTC (2 trip detection logic). Purge VSV stuck closed During sequence D, the canister pressure sensor measures the EVAP system pressure. The pressure measurement for purge VSV monitor is begun when the purge VSV is turned on (open) after the EVAP leak check. When the measured pressure indicates an increase of 0.3 kPa(gauge) [2.25 mmHg(gauge)] or higher, the purge VSV is functioning normally. If the pressure does not increase, the ECM interprets this as the purge VSV being stuck closed. The ECM illuminates the MIL and stores the DTC (2 trip detection logic).
2. PURGE FLOW MONITOR The purge flow monitor consists of the two step monitors. The 1st monitor is conducted every time and the 2nd monitor is activated if necessary.

1. The 1st monitor While the engine is running and the purge VSV (Vacuum Switching Valve) is on (open), the ECM monitors the purge flow by measuring the EVAP pressure change. If negative pressure is not created, the ECM begins the 2nd monitor.
2. The 2nd monitor The vent valve is turned on (closed) and the EVAP pressure is then measured. If the variation in the pressure is less than 0.5 kPa(gauge) [3.751 mmHg(gauge)], the ECM interprets this as the Purge VSV being stuck closed. The ECM illuminates the MIL and stores DTC P0441 (2 trip detection logic).

Atmospheric pressure check

In order to ensure reliable malfunction detection, the variation between the atmospheric pressure, before and after conduction of the purge flow monitor is measured by the ECM.

The description can be found in the EVAP (evaporative emission) System. Refer to DESCRIPTION.

Scheme 359

1. DTC P0451: Canister pressure sensor abnormal voltage fluctuation If the canister pressure sensor voltage output fluctuates rapidly for 10 seconds, the ECM stops the EVAP system monitor. The ECM interprets this as the canister pressure sensor voltage fluctuating, and stops the EVAP system monitor. The ECM then illuminates the MIL and stores the DTC (2 trip detection logic).
2. DTC P0452: Canister pressure sensor voltage low If the canister pressure sensor voltage output (pressure) is less than 0.45 V: 42.11009 kPa(abs) [315.86779 mmHg(abs)], the ECM interprets this as an open or short circuit in the canister pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and stores the DTC (1 trip detection logic).
3. DTC P0453: Canister pressure sensor voltage high If the canister pressure sensor voltage output (pressure) is higher than 4.9 V: 123.76147 kPa(abs) [928.33479 mmHg(abs)], the ECM interprets this as an open or short circuit in the canister pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and stores the DTC (1 trip detection logic).

The idle speed is controlled by the ETCS (Electronic Throttle Control System). The ETCS 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 ETCS. 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 idling air flow volume to conduct Idle Speed Control (ISC). The ECM determines that the ISC system is malfunctioning if either of the following conditions is met

Scheme 360

1. The difference between the target engine idle speed and actual engine idle 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 idle speed exceeds the threshold 5 times or more during a driving cycle, and then the system determines that the IAC flow rate learned value is stuck at the upper or lower limit, or that the IAC flow rate learned value has been changed by an amount that exceeds the threshold.

This monitor will run when the engine is started at an engine coolant temperature of -10 to 65°C (14 to 149°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 less than 65°C (149°F), the ECM measures the accumulated mass air flow at idle. If it 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 negative (-) auxiliary battery terminal is disconnected during inspection or repairs, the idle speed control (ISC) learned values are cleared. Idle speed control learning needs to be performed before this DTC can be stored. To perform idle speed control learning, the engine must be warmed up by allowing it to idle for 5 minutes. For idle speed control learning to be successful, when the engine is started to warm it up, there must be at least 10 seconds of idling with the coolant temperature less than 50°C (122°F) before allowing it to continue running for the 5 minute learning period.

Scheme 361

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 less than 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 negative (-) auxiliary battery terminal is disconnected during inspection or repairs, the idle speed control learned values are cleared. Idle speed control learning needs to be performed before this DTC can be stored. To perform idle speed control learning, the engine must be warmed up by allowing it to idle for 5 minutes. For idle speed control learning to be successful, when the engine is started to warm it up, there must be at least 10 seconds of idling with the coolant temperature less than 50°C (122°F) before allowing it to continue running for the 5 minute learning period.

Scheme 362

The auxiliary battery supplies electricity to the ECM even when the power switch is off. This power allows the ECM to store data such as DTC history, freeze frame data and fuel trim values. If the auxiliary 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 or the data stored in the ECM is may be partially cleared.

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

The ECM continuously monitors its main and sub CPUs. This self-check ensures that the ECM is functioning properly. If outputs from these 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 stored.

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

The ECM monitors the signals received from the throttle position sensor No. 1. As the ECM monitors the input signal of the throttle position sensor No. 1, if the input signal and control signal deviate, the DTC is stored.

The ECM monitors its internal operation and 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.

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 power switch is turned off. If the output voltage is higher than 7 V when the power switch is turned off, the ECM illuminates the MIL and stores the DTC when the power switch is turned on (IG).

HINT

*: Data List name

This DTC is designed to detect a deviation in the output characteristics of a pressure sensor.

The pressure of the canister pressure sensor and manifold absolute pressure sensor is monitored 50 minutes after the power switch is turned off. If there is a difference in the pressures, the MIL is illuminated (2 trip detection logic).

HINT

Correct judgment may not be possible when the altitude is 4000 m (13124 ft) or higher.

The description can be found in the EVAP (evaporative emission) System. Refer to DESCRIPTION.

Scheme 363

Scheme 364

1. P1420: EVAP (evaporative emission) small leak In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than the second reference pressure, the ECM determines that the EVAP system has a small leak, illuminates the MIL and stores the DTC (2 trip detection logic).
2. P1421: EVAP gross leak In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than [second reference pressure x 0.2] (near atmospheric pressure), the ECM determines that the EVAP system has a large leak, illuminates the MIL and stores the DTC (2 trip detection logic).

The description can be found in the EVAP (evaporative emission) System. Refer to DESCRIPTION.

Scheme 365

1. P1422: Fuel tank small leak In operation G, the leak detection pump creates negative pressure (vacuum) in the fuel tank and the fuel tank pressure is measured. If the stabilized system pressure is higher than the third reference pressure, the ECM determines that the fuel tank has a small leak. The ECM illuminates the MIL and stores the DTC (2 trip detection logic).
2. P1423: Fuel tank gross leak In operation G, the leak detection pump creates negative pressure (vacuum) in the fuel tank and the fuel tank pressure is measured. If the stabilized system pressure is higher than [third reference pressure x 0.2] (near atmospheric pressure), the ECM determines that the fuel tank has a large leak. The ECM illuminates the MIL and stores the DTC (2 trip detection logic).

See also:
• COMPONENTS
• ON-VEHICLE INSPECTION
• COMPONENTS
• REMOVAL