Engine Controls - Self-Diagnostics - Except 2.0L Turbo: Overview

Description

While the engine is running, the Volume Airflow (VAF) sensor outputs a pulse signal which corresponds to the volume of air flow. The ECM or PCM checks whether the frequency of this signal output by the VAF sensor while the engine is running is at or above the set value. When the throttle position sensor output voltage is low, the ECM or PCM causes the power transistor to be ON to send an airflow sensor reset signal to the VAF sensor. In response to the reset signal, the VAF sensor resets the filter circuit and improves the ability of the airflow sensor to measure the amount of air in a small air intake region.

Operation

The VAF sensor power is supplied from the MFI relay (terminal No. 4) and ground is provided on ECM harness connector C-119 terminal No. 40 (M/T) or PCM harness connector C-120 terminal No. 16 (A/T). A 5-volt power is applied to the VAF sensor output terminal (terminal No. 3) from ECM (terminal No. 90) or PCM (terminal No. 65). The VAF sensor generates a pulse signal when the output terminal and ground are opened/closed (open/short).

(Схема №11), (Схема №15), (Схема №28) and (Схема №29).

While engine is running, the Volume Airflow (VAF) sensor outputs a pulse signal which corresponds to the volume of air flow. The ECM (M/T) or PCM (A/T) checks whether the frequency of this signal output by the VAF sensor while the engine is running is at or above the set value.

The VAF sensor power is supplied from the MFI relay (terminal No. 4), and the ground is provided on the ECM (terminal No. 40 - M/T) or PCM (terminal No. 16 - A/T). A 5-volt power is applied to the VAF sensor output terminal (terminal No. 3) from the ECM (terminal No. 90 - M/T) or PCM (terminal No. 65 - A/T). The VAF sensor generates a pulse signal when the output terminal and ground are opened/closed (open/short).

(Схема №11), (Схема №15), (Схема №28) and (Схема №29).

A 5-volt voltage is supplied to the BARO sensor power terminal (terminal No. 1) from the ECM (terminal No. 81) or PCM (terminal No. 46). The ground terminal (terminal No. 5) is grounded with ECM (terminal No. 40) or PCM (terminal No. 16). A voltage that is proportional to the atmospheric pressure is sent to the ECM (terminal No. 85) or PCM (terminal No. 55) from the BARO sensor output terminal (terminal No. 2). The BARO pressure sensor outputs a voltage which corresponds to the barometric pressure. The ECM or PCM checks whether this voltage is within a specified range.

(Схема №11), (Схема №15), (Схема №28) and (Схема №30).

A 5-volt voltage is supplied to the BARO sensor power terminal (terminal No. 1) from the ECM (terminal No. 81 - M/T) or PCM (terminal No. 46 - A/T). The ground terminal (terminal No. 5) is grounded with ECM (terminal No. 40 - M/T) or PCM (terminal No. 16 - A/T). A voltage that is proportional to the atmospheric pressure is sent to the ECM (terminal No. 85 - M/T) or PCM (terminal No. 55 - A/T) from the BARO sensor output terminal (terminal No. 2). The BARO sensor outputs a voltage which corresponds to the barometric pressure. The ECM (M/T) or PCM (A/T) checks whether this voltage is within a specified range.

(Схема №11), (Схема №15), (Схема №28) and (Схема №30).

The BARO sensor outputs a voltage which corresponds to the barometric pressure. The ECM (M/T) or PCM (A/T) checks whether this voltage is within a specified range.

A 5-volt voltage is supplied to the BARO sensor power terminal (terminal No. 1) from the ECM (terminal No. 81) or PCM (terminal No. 46 - A/T). The ground terminal (terminal No. 5) is grounded with ECM (terminal No. 40) or PCM (terminal No. 16 - A/T). A voltage that is proportional to the atmospheric pressure is sent to the ECM (terminal No. 85) or PCM (terminal No. 55 - A/T) from the BARO sensor output terminal (terminal No. 2).

(Схема №11), (Схема №15), (Схема №28) and (Схема №30).

The Intake Air Temperature (IAT) sensor converts the intake air temperature to voltage. The ECM (M/T) or PCM (A/T) checks whether this voltage is within a specified range.

About 5 volts are applied to the IAT sensor output terminal (terminal No. 6) from the ECM (terminal No. 72 - M/T) or PCM (terminal No. 64 - A/T) via the resistor in the ECM (M/T) or PCM (A/T). The ground terminal (terminal No. 5) is grounded with ECM (terminal No. 40 - M/T) or PCM (terminal No. 16 - A/T). The intake air temperature sensor is a negative temperature coefficient type of resistor. When intake air temperature rises, resistance decreases. The intake air temperature sensor output voltage increases when resistance increases and decreases when resistance decreases.

(Схема №11), (Схема №15), (Схема №28) and (Схема №31).

The Intake Air Temperature (IAT) sensor converts the intake air temperature to voltage. The ECM or PCM checks whether this voltage is within a specified range.

About 5 volts are applied to the IAT sensor output terminal (terminal No. 6) from the ECM (terminal No. 72) or PCM (terminal No. 64) via the resistor in the ECM or PCM. The ground terminal (terminal No. 5) is grounded with ECM (terminal No. 40) or PCM (terminal No. 16). The IAT sensor is a negative temperature coefficient type of resistor. When the intake air temperature rises, resistance decreases. The intake air temperature sensor output voltage increases when resistance increases and decreases when resistance decreases.

(Схема №11), (Схема №15), (Схема №28) and (Схема №31).

The Intake Air Temperature (IAT) sensor converts the intake air temperature to voltage. The ECM (M/T) or PCM (A/T) checks whether this voltage is within a specified range.

About 5 volts are applied to the IAT sensor output terminal (terminal No. 6) from the ECM (terminal No. 72 - M/T) or PCM (terminal No. 64 - A/T) via the resistor in the ECM (M/T) or PCM (A/T). The ground terminal (terminal No. 5) is grounded with ECM (terminal No. 40 - M/T) or PCM (terminal No. 16 - A/T). The IAT sensor is a negative temperature coefficient type of resistor. When intake air temperature rises, resistance decreases. The intake air temperature sensor output voltage increases when resistance increases and decreases when resistance decreases.

(Схема №11), (Схема №15), (Схема №28) and (Схема №31).

The Engine Coolant Temperature (ECT) sensor converts the engine coolant temperature to a voltage and outputs it. The ECM (M/T) or PCM checks whether this voltage is within a specified range.

A 5-volt reference voltage is applied to the ECT sensor output terminal (terminal No. 1) from the ECM (terminal No. 83 - M/T) or PCM (terminal No. 44) via the resistor in the ECM (M/T) or PCM (A/T). The ground terminal (terminal No. 2) is grounded with ECM (terminal No. 92 - M/T) or PCM (terminal No. 57). The ECT sensor is a negative temperature coefficient type of resistor. It has the characteristic that when the engine coolant temperature rises the resistor decreases. The engine coolant temperature sensor output voltage increases when resistor increases and decreases when resistor decreases.

(Схема №11), (Схема №15), (Схема №17) and (Схема №32).

The Engine Coolant Temperature (ECT) sensor converts engine coolant temperature to a voltage and outputs it. The ECM (M/T) or PCM (A/T) checks whether this voltage is within a specified range.

A 5-volt voltage is applied to the ECT sensor output terminal (terminal No. 1) from the ECM (terminal No. 83 - M/T) or PCM (terminal No. 44 - A/T) via the resistor in the ECM (M/T) or PCM (A/T). The ground terminal (terminal No. 2) is grounded with ECM (terminal No. 92 - M/T) or (terminal No. 57 - A/T). The ECT sensor is a negative temperature coefficient type of resistor. It has the characteristic that when the engine coolant temperature rises, the resistor decreases. The engine coolant temperature sensor output voltage increases when resistor increases and decreases when resistor decreases.

(Схема №11), (Схема №15), (Схема №17) and (Схема №32).

The Engine Coolant Temperature (ECT) sensor converts the engine coolant temperature to a voltage and outputs it. The ECM or PCM checks whether this voltage is within a specified range.

(Схема №11), (Схема №15), (Схема №17) and (Схема №32).

The Throttle Position (TP) sensor outputs voltage which corresponds to the throttle valve opening angle. The ECM or PCM checks whether the voltage is within a specified range.

A 5-volt power supply is applied on the TP sensor power terminal (terminal No. 3) from the ECM (terminal No. 81 - M/T) or PCM (terminal No. 46 - A/T). The ground terminal (terminal No. 2) is grounded with ECM (terminal No. 92 - M/T) or PCM (terminal No. 57 - A/T). When the throttle valve shaft is turned from idle position to fully opened position, the resistor between the TP sensor output terminal (terminal No. 1) and ground terminal will increase according to the rotation.

(Схема №11), (Схема №15), (Схема №26) and (Схема №33).

The Throttle Position (TP) sensor outputs voltage which corresponds to the throttle valve opening angle. The ECM or PCM (A/T) checks whether the voltage is within a specified range. In addition, it checks that the voltage output does not become too high while engine is at idle.

A 5-volt power supply is applied on the TP sensor power terminal (terminal No. 3) from the ECM (terminal No. 81 - M/T) or PCM (terminal No. 46 - A/T). The ground terminal (terminal No. 2) is grounded with ECM (terminal No. 92 - M/T) or PCM (terminal No. 57 - A/T). When throttle valve shaft is turned from idle position to the fully opened position, the resistor between the TP sensor output terminal (terminal No. 1) and ground terminal will increase according to the rotation.

(Схема №11), (Схема №15), (Схема №26) and (Схема №33).

The Throttle Position (TP) sensor outputs voltage which corresponds to the throttle valve opening angle. The ECM (M/T) or PCM (A/T) checks whether voltage is within a specified range. In addition, it checks that the voltage output does not become too high while engine is at idle.

A 5-volt power supply is applied on the TP sensor power terminal (terminal No. 3) from ECM (terminal No. 81 - M/T) or PCM (terminal No. 46 - A/T). The ground terminal (terminal No. 2) is grounded with ECM (terminal No. 92 - M/T) or PCM (terminal No. 57 - A/T). When throttle valve shaft is turned from the idle position to the fully opened position, the resistor between the TP sensor output terminal (terminal No. 1) and ground terminal will increase according to the rotation.

(Схема №11), (Схема №15), (Схема №26) and (Схема №33).

The engine coolant temperature sensor varies resistance due to engine coolant temperature. The ECM (M/T) or PCM (A/T) supplies voltage to sensor. Voltage changes due to sensor resistance. ECM/PCM checks whether this voltage is within a specified range.

A 5-volt voltage is applied to the engine coolant temperature sensor output terminal (terminal No. 1) from the ECM (terminal No. 83 - M/T) or PCM (terminal No. 44 - A/T) via the resistor in the ECM (M/T) or PCM (A/T). The ground terminal (terminal No. 2) is grounded with ECM (terminal No. 92 - M/T) or (terminal No. 57 - A/T). The engine coolant temperature sensor is a negative temperature coefficient type of resistor. It has the characteristic that when engine coolant temperature rises the resistance decreases. The engine coolant temperature sensor output voltage increases when resistance increases and decreases when resistance decreases.

(Схема №11), (Схема №15), (Схема №17) and (Схема №32).

The ECM or PCM checks the time for the engine coolant temperature to reach the judgment temperature.

The heated oxygen sensor (front) detects the concentration of oxygen in the exhaust gas; it converts that data to voltage, and inputs the resulting signals to the ECM (M/T) or PCM (A/T). When the heated oxygen sensor (front) begins to deteriorate, the heated oxygen sensor signal response becomes poor. The ECM (M/T) or PCM (A/T) forcibly varies the air/fuel mixture to make it leaner and richer, and checks the response speed of the heated oxygen sensor (front). In addition, the ECM (M/T) or PCM (A/T) also checks for an open circuit in the heated oxygen sensor (front) output line.

(Схема №11), (Схема №21) and (Схема №34).

The front Heated Oxygen Sensor (HO2S) detects the concentration of oxygen in the exhaust gas; it converts those data to voltage, and inputs the resulting signals to the ECM (M/T) or PCM (A/T). When the front HO2S begins to deteriorate, the heated oxygen sensor signal response becomes poor. The ECM (M/T) or PCM (A/T) forcibly varies the air/fuel mixture to make it leaner and richer, and checks the response speed of the front HO2S. In addition, the ECM (M/T) or PCM (A/T) also checks for an open circuit in front HO2S output line.

(Схема №11), (Схема №21) and (Схема №34).

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM (terminal No. 76 - M/T) or PCM (terminal No. 71 - A/T) from the output terminal (terminal No. 4) of the front HO2S. Terminal No. 2 of the front HO2S is grounded with ECM (terminal No. 92 - M/T) or PCM (terminal No. 57 - A/T).

(Схема №15), (Схема №21) and (Схема №34).

The ECM (M/T) or PCM (A/T) effects air/fuel ratio feedback control in accordance with the signals from the heated oxygen sensor (front). If the heated oxygen sensor (front) has deteriorated, corrections will be made by the heated oxygen sensor (rear). DTC P0134 becomes stored in memory if a failure is detected in the above air/fuel ratio feedback control system.

Refer to DTC P0130: HEATED OXYGEN SENSOR CIRCUIT (SENSOR 1) and DTC P0201, DTC P0202, DTC P0203 OR DTC P0204.

(Схема №15), (Схема №21) and (Схема №34).

The ECM (M/T) or PCM (A/T) checks whether the heater current is within a specified range when the heater is energized.

Power is supplied from the MFI relay (terminal No. 4) to the heated oxygen sensor (front) heater. The ECM (terminal No. 60 - M/T) or PCM (terminal No. 3 - A/T) controls continuity to the heated oxygen sensor (front) heater by turning the power transistor on and off in the ECM (M/T) or PCM (A/T).

(Схема №15), (Схема №21) and (Схема №35).

The output signal of the heated oxygen sensor (front) is compensated by the output signal of the heated oxygen sensor (rear). The ECM (M/T) or PCM (A/T) checks for an open circuit in the heated oxygen sensor (rear) output line.

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM (terminal No. 75 - M/T) or PCM (terminal No. 73 - A/T) from the output terminal (terminal No. 1) of the heated oxygen sensor (rear). Terminal No. 2 of the heated oxygen sensor (rear) is grounded with ECM (terminal No. 92 - M/T) or PCM (terminal No. 57 - A/T).

(Схема №15), (Схема №22) and (Схема №37).

Power is supplied from the MFI relay (terminal No. 4) to the heated oxygen sensor (rear) heater. The ECM (terminal No. 54 - M/T) or PCM (terminal No. 26 - A/T) controls continuity to the heated oxygen sensor (rear) heater by turning the power transistor in the ECM (M/T) or PCM (A/T) on and off. The ECM (M/T) or PCM (A/T) checks whether the heater current is within a specified range when the heater is energized.

(Схема №15), (Схема №22) and (Схема №38).

If a malfunction occurs in the fuel system, the fuel trim value becomes too large. The ECM (M/T) or PCM (A/T) checks whether the fuel trim value is within a specified range.

Refer to DTC P0201, DTC P0202, DTC P0203 OR DTC P0204. (Схема №11)and (Схема №40).

If a malfunction occurs in the fuel system, the fuel trim value becomes too small. The ECM (M/T) or PCM (A/T) checks whether the fuel trim value is within a specified range.

Refer to DTC P0201, DTC P0202, DTC P0203 OR DTC P0204. (Схема №11), (Схема №15) and (Схема №40).

The fuel temperature sensor converts fuel temperature to a voltage. The ECM (M/T) or PCM (A/T) detects fuel temperature in the fuel tank with this output voltage.

A 5-volt voltage is applied to the fuel temperature sensor output terminal (terminal No. 3) from the ECM (terminal No. 77) or PCM (terminal No. 51) via the resistor in the ECM (M/T) or PCM (A/T). The fuel temperature sensor output voltage increases when resistance increases and decreases when resistance decreases. The ground terminal (terminal No. 2) is grounded to vehicle body. (Схема №15)and (Схема №39).

The fuel temperature sensor converts fuel temperature to voltage. The ECM (M/T) or PCM (A/T) detects fuel temperature in fuel tank with this output voltage.

A 5-volt voltage is applied to fuel temperature sensor output terminal (terminal No. 3) from ECM (terminal No. 77 - M/T) or PCM (terminal No. 51 - A/T) via the resistor in the ECM (M/T) or PCM (A/T). The fuel temperature sensor output voltage increases when resistance increases and decreases when resistance decreases. The ground terminal (terminal No. 2) is grounded to vehicle body. (Схема №15)and (Схема №39).

The fuel temperature sensor converts the fuel temperature to voltage. The ECM (M/T) or PCM (A/T) detects fuel temperature in fuel tank with the output voltage.

A 5-volt voltage via the resistor in the ECM or PCM is applied to fuel temperature sensor output terminal (terminal No. 3) from the ECM (terminal No. 77 - M/T) or PCM (terminal No. 51 - A/T). The fuel temperature sensor output voltage increases when resistance increases and decreases when resistance decreases. The ground terminal (terminal No. 2) is grounded to vehicle body. (Схема №15)and (Схема №39).

The amount of fuel injected by the injector is controlled by the amount of time the coil is grounded by the ECM (M/T) or PCM (A/T). A surge voltage is generated when injectors are driven and the current flowing to the injector coil is shut off. The ECM (M/T) or PCM (A/T) checks this surge voltage.

The injector power is supplied from the MFI relay to each injector (terminal No. 4). The ECM (M/T) or PCM (A/T) controls the injector by turning the power transistor in the ECM (M/T) or PCM (A/T) on and off.

(Схема №11), (Схема №15), (Схема №25) and (Схема №40).

If a misfire occurs while the engine is running, the engine speed changes for an instant. The ECM or PCM checks for such changes in engine speed.

Refer to DTC P0201, DTC P0202, DTC P0203 OR DTC P0204. (Схема №11)and (Схема №40).

If a misfire occurs while engine is running, engine speed changes for an instant. The ECM or PCM checks for such changes in engine speed.

Refer to DTC P0201, DTC P0202, DTC P0203 OR DTC P0204. (Схема №11)and (Схема №40).

The knock sensor converts the vibration of the cylinder block into a voltage and outputs it. If there is a malfunction of the knock sensor, the voltage output will not change. The ECM (M/T) or PCM (A/T) checks whether the voltage output changes.

The knock sensor sends a signal voltage to the ECM (terminal No. 78 - M/T) or PCM (terminal No. 90 - A/T). (Схема №11), (Схема №15), (Схема №23) and (Схема №42).

The crankshaft position sensor detects the crank angle (position) of each cylinder, and converts that data to pulse signals, which are then input to the ECM (M/T) or PCM (A/T) When the engine is running, the crankshaft position sensor outputs a pulse signal. The ECM (M/T) or PCM (A/T) checks whether pulse signal is input while the engine is cranking.

The crankshaft position sensor power is supplied from MFI relay (terminal No. 4). Terminal No. 1 of the crankshaft position sensor is grounded with ECM (terminal No. 40 - M/T) or PCM (terminal No. 16 - A/T). A 5-volt voltage is applied on the crankshaft position sensor output terminal (terminal No. 3) from the ECM (terminal No. 89 - M/T) or PCM (terminal No. 45 - A/T). The crankshaft position sensor generates a pulse signal when the output terminal is opened and grounded.

(Схема №11), (Схема №13), (Схема №15) and (Схема №43).

The camshaft position sensor functions to detect the top dead center position of the number 1 cylinder and to convert that data to pulse signals that are input to the ECM (M/T) or PCM (A/T). When engine is running, camshaft position sensor outputs a pulse signal. The ECM (M/T) or PCM (A/T) checks whether pulse signal is input while the engine is cranking.

The camshaft position sensor power is supplied from the MFI relay (terminal No. 4). Terminal No. 1 of the camshaft position sensor is grounded with ECM (terminal No. 40 - M/T) or PCM (terminal No. 16 - A/T). A 5-volt voltage is applied on the camshaft position sensor output terminal (terminal No. 2) from the ECM (terminal No. 88 - M/T) or PCM (terminal No. 56 - A/T). The camshaft position sensor generates a pulse signal when the output terminal is opened and grounded.

(Схема №11), (Схема №12), (Схема №15), (Схема №25) and (Схема №45).

When Exhaust Gas Recirculation (EGR) solenoid switches from OFF to ON while engine is running, EGR gas flows. The ECM (M/T) or PCM (A/T) checks how the EGR gas flow signal changes. (Схема №11), (Схема №16) and (Схема №46).

To judge if there is an open circuit in the EGR solenoid drive circuit, ECM (M/T) or PCM (A/T) measures the surge voltage of the EGR solenoid coil. The ECM (M/T) or PCM (A/T) drives the EGR solenoid. After the solenoid is turned off, the ECM (M/T) or PCM (A/T) will check if the solenoid coil produces a surge voltage of 2 volts or more.

The EGR solenoid power is supplied from the MFI relay (terminal No. 4). The ECM (M/T) or PCM (A/T) controls the EGR solenoid ground by turning the power transistor in the ECM (M/T) or PCM (A/T) on and off.

(Схема №11), (Схема №15), (Схема №16), (Схема №25) and (Схема №46).

The signal from the rear heated oxygen sensor differs from the front heated oxygen sensor. That is because the catalytic converter purifies the exhaust gas. When the catalytic converter has deteriorated, the signal from the front heated oxygen sensor becomes similar to the rear heated oxygen sensor. The ECM (M/T) or PCM (A/T) compares the output of the front and rear heated oxygen sensor signals.

ECM (M/T) or PCM (A/T) detects stuck open of evaporative emission purge solenoid valve and stuck close of evaporative emission ventilation solenoid valve by pressure change in fuel tank. Stuck open of evaporative emission purge solenoid valve is judged through monitoring leak of evaporative emission control system. Stuck close of evaporative emission ventilation solenoid valve is judged after 20 seconds of end of monitoring leak of evaporative emission control system, or of usual operation of evaporative emission purge solenoid from ON to OFF.

(Схема №11), (Схема №16) and (Схема №18).

To judge if there is leak in the fuel system, ECM (M/T) or PCM (A/T) measure the change of the pressure inside the fuel tank. The ECM or PCM turns on the evaporative emission ventilation solenoid to shut off the evaporative emission canister outlet port. Then the evaporative emission purge solenoid is driven to set the fuel system into a negative pressure. When the fuel system develops a vacuum of 0.29 psi (2 kPa), the evaporative emission purge solenoid is turned OFF and fuel system vacuum is maintained at 0.29 psi (2 kPa). The ECM or PCM determines if there is leak in the fuel system by measuring the change of vacuum inside the fuel tank. The test is stopped when fuel vapor pressure is judged as too high. (Схема №11), (Схема №18) and (Схема №47).

To judge if there is open circuit in the evaporative emission purge solenoid drive circuit, ECM or PCM measures the surge voltage of evaporative emission ventilation solenoid coil. The ECM or PCM drives the evaporative emission purge solenoid. After solenoid is turned off, ECM or PCM will check if solenoid coil produces a surge voltage of 2 volts or more.

Power to the evaporative emission purge solenoid power is supplied from the MFI relay (terminal No. 4). The ECM (M/T) or PCM (A/T) controls ground circuit of the evaporative emission purge solenoid by turning the power transistor in the ECM or PCM on and off.

(Схема №15), (Схема №16), (Схема №25) and (Схема №49).

To judge if there is an open circuit in the evaporative emission ventilation solenoid drive circuit, ECM (M/T) or PCM (A/T) measures the surge voltage of the evaporative emission ventilation solenoid coil. The ECM or PCM drives the evaporative emission ventilation solenoid. After the solenoid is turned off, the ECM or PCM will check if the solenoid coil produces a surge voltage of 2 volts or more.

The evaporative emission ventilation solenoid power is supplied from the MFI relay (terminal No. 4). The ECM (M/T) or PCM (A/T) controls the evaporative emission ventilation solenoid ground by turning the power transistor in the ECM or PCM ON and OFF.

(Схема №15), (Схема №18), (Схема №25) and (Схема №50).

The ECM (M/T) or PCM (A/T) monitors the fuel tank differential pressure sensor signal voltage. The ECM (M/T) or PCM (A/T) determines whether the fuel tank differential pressure sensor signal voltage is within normal operating parameters.

The ECM (terminal 81 - M/T) or PCM (terminal 46 - A/T) supplies a 5-volt reference signal to the fuel tank differential pressure snesor (terminal 3). The fuel tank differential pressure sensor (terminal 2) is grounded through the ECM (terminal 81 - M/T) or PCM (terminal 57 - A/T). The fuel tank differential pressure sensor (terminal 1) returns a voltage signal to the ECM (terminal 81 - M/T) or PCM (terminal 92 - A/T) that is proportional to the pressure in the fuel tank. (Схема №15), (Схема №19), (Схема №47) and (Схема №51).

Overview Of Troubleshooting

DTC P0451 can be set by faulty fuel differential pressure sensor, related circuit or faulty ECM (M/T) or PCM (A/T).

To check a system blockage, do a performance test which uses a mechanical vacuum gauge and scan tool set on the fuel tank differential pressure sensor (TANK PRS SNSR 73.) The mechanical gauge reading is used to verify scan tool reading. A comparison of the mechanical gauge to scan tool determines problem in the system.

To judge if the fuel tank differential pressure sensor is defective, the ECM (M/T) or PCM (A/T) monitors the fuel tank differential pressure sensor output voltage. Based on the test conditions and judgment criteria, the ECM (M/T) or PCM (A/T) judges if the fuel tank differential pressure sensor output voltage is normal.

A 5-volt voltage is supplied to the power terminal of the fuel tank differential pressure sensor (terminal No. 3) from the ECM (terminal No. 81 - M/T) or PCM (terminal No. 46 - A/T). The ground terminal (terminal No. 2) is grounded with the ECM (terminal No. 92 - M/T) or PCM (terminal No. 57 - A/T). A voltage proportional to the pressure in the fuel tank is sent from the output terminal of the fuel tank differential pressure sensor (terminal No. 1) to the ECM (terminal No. 61 - M/T) or PCM (terminal No. 92 - A/T). (Схема №15), (Схема №19), (Схема №47) and (Схема №51).

The DTC P0452 can be set if either faulty fuel differential pressure sensor, related circuit or ECM (M/T) or PCM (A/T).

To check a system blockage, do a performance test which uses a mechanical vacuum gauge and scan tool set on the fuel tank differential pressure sensor (TANK PRS SNSR73). The mechanical gauge reading is used to verify scan tool reading. A comparison of the mechanical gauge to scan tool determines the problem in the system.

The DTC P0453 can be set if a faulty fuel differential pressure sensor, related circuit or ECM (M/T) or PCM (A/T) exists. To check a system blockage, do a performance test which uses a mechanical vacuum gauge and scan tool set on the fuel tank differential pressure sensor (TANK PRS SNSR73.) The mechanical gauge reading is used to verify scan tool reading. A comparison of the mechanical gauge to scan tool determines the problem in the system.

The fuel tank may be under a slight pressure or vacuum depending on the state of the evaporative emission (EVAP) system. The ECM (M/T) or PCM (A/T) monitors and responds to these pressure/vacuum changes. If the pressure/vacuum varies from the specified range, the ECM (M/T) or PCM (A/T) will set DTC P0455. The ECM (M/T) or PCM (A/T) energizes the evaporative emission ventilation solenoid to shut off the evaporative emission canister outlet port. The evaporative emission purge solenoid is activated to apply engine manifold vacuum to the EVAP system. When the fuel system develops a vacuum of 0.29 psi (2 kPa), the evaporative emission purge solenoid is turned off and the fuel system vacuum is maintained at 0.29 psi (2 kPa). The ECM (M/T) or PCM (A/T) determines whether there is a leak or clog in the fuel system by measuring the change in vacuum inside the fuel tank. The test is stopped when fuel vapor pressure is determined to be too high. (Схема №11)and (Схема №47).

To determine the cause of DTC P0455, a performance test is needed. The performance test uses a mechanical vacuum gauge and scan tool on the fuel tank differential pressure sensor (TANK PRES SNER 73). The mechanical gauge reading is used to verify scan tool reading. A comparison of the mechanical gauge reading to scan tool reading determines the reading problem in the system. Prior to doing the performance test, several simple inspections are needed to exclude some possibilities of the symptom.

The ECM (M/T) or PCM (A/T) monitors the Evaporative Emission (EVAP) System pressure. The ECM (M/T) or PCM (A/T) controls the evaporative emission ventilation solenoid. It closes the evaporative emission ventilation solenoid to seal the evaporative emission canister side of the system. The evaporative emission purge solenoid is opened to allow manifold vacuum to create low pressure (vacuum) in the EVAP system. When the EVAP system develops a vacuum of 0.29 psi (2 kPa), the evaporative emission purge solenoid is closed and the fuel system vacuum is maintained at 0.29 psi (2 kPa). The ECM (M/T) or PCM (A/T) determines whether there is a leak in the EVAP system by monitoring the vacuum inside the fuel tank. The test is stopped when fuel vapor pressure exceeds predetermined limits. (Схема №11)and (Схема №47).

To determine the cause of DTC P0456, a performance test is needed. The performance test uses a mechanical vacuum gauge and scan tool set on the fuel tank differential pressure sensor (TANK PRES SNER 73.) The mechanical gauge reading is used to verify scan tool reading. A comparison of the mechanical gauge to scan tool determines the problem in the system. Prior to doing the performance test, several simple inspections are needed to exclude some possibilities of the symptom.

The drive signal from the fuel gauge circuit is split to the gauge and to input in ECM (M/T) or PCM (A/T). The ECM (M/T) or PCM (A/T) detects the amount of fuel left in the fuel tank with this signal, and also controls the fuel level warning light.

The fuel gauge drive signal is input in ECM (terminal No. 74 - M/T) or PCM (terminal No. 60 - A/T). (Схема №15)and (Схема №52).

The vehicle speed sensor converts vehicle speed into pulse signals and inputs them to the ECM. The vehicle speed sensor outputs a pulse signal while the vehicle is driven. The ECM checks whether the pulse signal is output.

A 5-volt voltage is applied to the vehicle speed sensor output terminal (terminal No. 3) from the ECM (terminal No. 86). The vehicle speed sensor generates a pulse signal when the output terminal is opened and grounded. (Схема №11), (Схема №15), (Схема №27) and (Схема №53).

The amount of air taken in during idling is regulated by the opening and closing of the servo valve located in the air passage that bypasses the throttle body. If there is a malfunction of the IAC system, the actual engine speed will not be identical to the target engine speed. The ECM (M/T) or PCM (A/T) checks the difference between actual engine speed and target engine speed.

The idle air control motor power is supplied from the MFI relay (terminal No. 4). The ECM (terminals No. 4, 5, 17 and 18 - M/T) or PCM (terminals No. 14, 15, 28 and 29 - A/T) drives the stepper motor by sequentially turning on the power transistors in the ECM (M/T) or PCM (A/T) and providing ground to the idle air control motor (terminals No. 1, 3, 4 and 6).

(Схема №11), (Схема №15) and (Схема №55).

The idle air control motor power is supplied from the MFI relay (terminal No. 4). The ECM (terminals No. 4, 5, 17 and 18 - M/T) or PCM (terminals No. 14, 15, 28 and 29 - A/T) drive the stepper motor by sequentially turning on the power transistors in the ECM or PCM and providing ground to the idle air control motor (terminals No. 1, 3, 4 and 6).

(Схема №11), (Схема №15) and (Схема №55).

The Power Steering Pressure Switch (PSPS) converts the existence of a power steering load into a high/low voltage, and inputs it into the ECM (M/T) or PCM (A/T). When steering wheel is turned, hydraulic pressure rises. The PSPS closes and the applied battery voltage will be grounded. With this, the PSPS output voltage will fluctuate between 12 volts and zero volts. While driving with the steering wheel in straight-ahead position, the PSPS turns off. The ECM (M/T) or PCM (A/T) checks whether the PSPS turns off or on during driving.

Battery voltage is applied to the PSPS output terminal (terminal No. 1) from the ECM (terminal No. 37 - M/T) or PCM (terminal No. 52 - A/T) via the resistor in the ECM or PCM. (Схема №11), (Схема №15) and (Схема №57).

When the generator field coils are controlled, the generator FR terminal inputs signal to the ECM (M/T) or PCM (A/T). The ECM (M/T) or PCM (A/T) detects the generator output with the input signal, and controls the idle air control motor according to the generator input.

The ECM (terminal 41 - M/T) or PCM (terminal 54 - A/T) apply a battery positive voltage into the generator FR terminal No. 4 via resistance inside the unit.

The manifold differential pressure sensor outputs a voltage which corresponds to the negative pressure in the intake manifold. The ECM (M/T) or PCM (A/T) checks whether the voltage output by manifold differential pressure sensor is within a specified range.

A 5-volt voltage is applied on the manifold differential pressure sensor power terminal (terminal No. 3) from the ECM (terminal No. 81 - M/T) or PCM (terminal No. 46 - A/T). The ground terminal (terminal No. 2) is grounded with the ECM (terminal No. 92 - M/T) or PCM (terminal No. 57 - A/T). A voltage proportional to the pressure in the intake manifold plenum is sent from the manifold differential pressure sensor output terminal (terminal No. 1) to the ECM (terminal No. 73 - M/T) or PCM (terminal No. 91 - A/T). (Схема №11), (Схема №15), (Схема №24) and (Схема №58).

The ECM (terminal No. 41 - M/T) or PCM (terminal No. 54 - A/T) applies battery voltage into the generator FR terminal No. 4 via resistance inside the unit. (Схема №15)and (Схема №59).

The ECM (M/T) or PCM (A/T) checks for open circuit in the battery backup line. When the system detects an open circuit in the battery backup line, it makes one failure judgment of other the DTCs. (Схема №15)and (Схема №60).

See also:
• FUEL PUMP RELAY & MFI RELAY

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Overview Of Troubleshooting

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