Engine Controls - Self-Diagnostics - 3.0L: Overview Mitsubishi Eclipse III

Description

The MIL power is supplied from the ignition switch. The ECM/PCM controls the ground of the MIL by turning a power transistor in the ECM/PCM on and off. The ECM/PCM causes the MIL to illuminate for 5 seconds immediately after the ignition switch is turned to ON position.

The MIL power is supplied from the ignition switch. The ECM/PCM controls the ground of the MIL by turning a power transistor in the ECM/PCM on and off. The ECM/PCM causes the MIL to illuminate for 5 seconds immediately after the ignition switch is turned to ON position.

A battery positive voltage is applied on the DLC power terminal (terminal No. 16). The ground terminals (terminals No. 4 and 5) are grounded to the vehicle body. The cause is probably a defect in power supply system (including ground) for the on-board diagnostic test mode line.

A diagnostic output is made from the ECM/PCM (terminal No. 85) to the diagnostic output terminal (terminal No. 7) of the DLC.

CONNECTOR IDENTIFICATION

Note. The following terminal illustrations are shown as viewed from component side of connector.

TERMINAL IDENTIFICATION DIRECTORY

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While the engine is running, the Volume Airflow (VAF) sensor outputs a pulse signal which corresponds to the volume of air flow. The ECM/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 (TP) sensor output voltage is low, the ECM/PCM causes the power transistor to be on to send a VAF 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 VAF 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 the ground is provided by the ECM (terminal No. 3) or PCM (terminal No. 16). 5-volt power is applied to the VAF sensor output terminal (terminal No. 3) from the ECM (terminal No. 61) or PCM (terminal No. 65). The VAF sensor generates a pulse signal when the output terminal and ground are opened/closed (Open/Short).

While the engine is running, the Volume Airflow (VAF) sensor outputs a pulse signal which corresponds to the volume of air flow. The ECM/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.

The VAF sensor power is supplied from the MFI relay (terminal No. 4), and the ground is provided by the ECM (terminal No. 3) or PCM (terminal No. 16). 5-volt power is applied to the VAF sensor output terminal (terminal No. 3) from the ECM (terminal No. 61) or PCM (terminal No. 65). The VAF sensor generates a pulse signal when the output terminal and ground are opened/closed (open/short).

The BARO pressure sensor outputs a voltage which corresponds to the barometric pressure. The ECM/PCM checks whether this voltage is within a specified range.

A 5-volt voltage is supplied to the BARO pressure sensor power terminal (terminal No. 1) from the ECM (terminal No. 42) or the PCM (terminal No. 46). The ground terminal (terminal No. 5) is grounded by ECM (terminal No. 34) or PCM (terminal No. 16). A voltage that is proportional to the atmospheric pressure is sent to the ECM (terminal No. 51) or PCM (terminal No. 55) from the barometric pressure sensor output terminal (terminal No. 2).

The BARO pressure sensor outputs a voltage which corresponds to the barometric pressure. The ECM/PCM checks whether this voltage is within a specified range.

A 5-volt voltage is supplied to the BARO pressure sensor power terminal (terminal No. 1) from the ECM (terminal No. 42) or the PCM (terminal No. 46). The ground terminal (terminal No. 5) is grounded by ECM (terminal No. 34) or PCM (terminal No. 16). A voltage that is proportional to the atmospheric pressure is sent to the ECM (terminal No. 51) or PCM (terminal No. 55) from the barometric pressure sensor output terminal (terminal No. 2).

The BARO pressure sensor outputs a voltage which corresponds to the barometric pressure. The ECM/PCM checks whether this voltage is within a specified range.

A 5-volt voltage is supplied to the BARO pressure sensor power terminal (terminal No. 1) from the ECM (terminal No. 42) or the PCM (terminal No. 46). The ground terminal (terminal No. 5) is grounded by ECM (terminal No. 34) or PCM (terminal No. 16). A voltage that is proportional to the atmospheric pressure is sent to the ECM (terminal No. 51) or PCM (terminal No. 55) from the barometric pressure sensor output terminal (terminal No. 2).

The IAT sensor converts the intake air temperature to a voltage. The ECM/PCM checks whether this voltage is within a specified range.

Approximately 5 volts are applied to the IAT sensor output terminal (terminal No. 6) from the ECM (terminal No. 62) or the PCM (terminal No. 64). The ground terminal (terminal No. 5) is grounded by ECM (terminal No. 34) or PCM (terminal No. 16). The IAT sensor is a negative temperature coefficient type of resistor. When the intake air temperature rises, the resistance decreases. The IAT sensor output voltage increases when the resistance increases and decreases when the resistance decreases.

The IAT sensor converts the intake air temperature to a voltage. The ECM/PCM checks whether this voltage is within a specified range.

Approximately 5 volts are applied to the IAT sensor output terminal (terminal No. 6) from the ECM (terminal No. 62) or the PCM (terminal No. 64). The ground terminal (terminal No. 5) is grounded by ECM (terminal No. 34) or PCM (terminal No. 16). The IAT sensor is a negative temperature coefficient type of resistor. When the intake air temperature rises, the resistance decreases. The IAT sensor output voltage increases when the resistance increases and decreases when the resistance decreases.

The IAT sensor converts the intake air temperature to a voltage. The ECM/PCM checks whether this voltage is within a specified range.

Approximately 5 volts are applied to the IAT sensor output terminal (terminal No. 6) from the ECM (terminal No. 62) or the PCM (terminal No. 64). The ground terminal (terminal No. 5) is grounded by ECM (terminal No. 34) or PCM (terminal No. 16). The IAT sensor is a negative temperature coefficient type of resistor. When the intake air temperature rises, the resistance decreases. The IAT sensor output voltage increases when the resistance increases and decreases when the resistance decreases.

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

Approximately 5 volts are applied to the ECT sensor output terminal (terminal No. 1) from the ECM/PCM (terminal No. 44) through a resistor in the ECM/PCM. The ground terminal (terminal No. 2) is grounded by ECM (terminal No. 49) or PCM (terminal No. 57). The ECT sensor is a negative temperature coefficient type of resistor. When the engine coolant temperature rises, the resistance decreases. The ECT sensor output voltage increases when the resistance increases and decreases when the resistance decreases.

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

Approximately 5 volts are applied to the ECT sensor output terminal (terminal No. 1) from the ECM/PCM (terminal No. 44) through a resistor in the ECM/PCM. The ground terminal (terminal No. 2) is grounded by ECM (terminal No. 49) or PCM (terminal No. 57). The ECT sensor is a negative temperature coefficient type of resistor. When the engine coolant temperature rises, the resistance decreases. The ECT sensor output voltage increases when the resistance increases and decreases when the resistance decreases.

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

Approximately 5 volts are applied to the ECT sensor output terminal (terminal No. 1) from the ECM/PCM (terminal No. 44) through a resistor in the ECM/PCM. The ground terminal (terminal No. 2) is grounded by ECM (terminal No. 49) or PCM (terminal No. 57). The ECT sensor is a negative temperature coefficient type of resistor. When the engine coolant temperature rises, the resistance decreases. The ECT sensor output voltage increases when the resistance increases and decreases when the resistance decreases.

The Throttle Position (TP) sensor outputs voltage which corresponds to the throttle valve opening angle. The ECM/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. 4) from the ECM (terminal No. 42) or PCM (terminal No. 46). The ground terminal (terminal No. 1) is grounded by ECM (terminal No. 49) or PCM (terminal No. 57). When the throttle valve shaft is turned from idle position to fully opened position, the resistance between the TP sensor output terminal (terminal No. 3) and ground terminal will increase according to the rotation.

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

A 5-volt power supply is applied on the TP sensor power terminal (terminal No. 4) from the ECM (terminal No. 42) or PCM (terminal No. 46). The ground terminal (terminal No. 1) is grounded by ECM (terminal No. 49) or PCM (terminal No. 57). When the throttle valve shaft is turned from idle position to fully opened position, the resistance between the TP sensor output terminal (terminal No. 3) and ground terminal will increase according to the rotation.

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

A 5-volt power supply is applied on the TP sensor power terminal (terminal No. 4) from the ECM (terminal No. 42) or PCM (terminal No. 46). The ground terminal (terminal No. 1) is grounded by ECM (terminal No. 49) or PCM (terminal No. 57). When the throttle valve shaft is turned from idle position to fully opened position, the resistance between the TP sensor output terminal (terminal No. 3) and ground terminal will increase according to the rotation.

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

5-volt voltage is applied to the ECT sensor output terminal (terminal No. 1) from the ECM/PCM (terminal No. 44) through a resistor in the ECM/PCM. The ground terminal (terminal No. 2) is grounded by ECM (terminal No. 49) or PCM (terminal No. 57). The ECT sensor is a negative temperature coefficient type of resistor. When the engine coolant temperature rises, the resistance decreases. The ECT sensor output voltage increases when the resistance increases and decreases when the resistance decreases.

The ECM/PCM checks the time for the engine coolant temperature to reach a predetermined judgment temperature.

The HO2S 1/1 detects the concentration of oxygen in the exhaust gas; it converts those data to voltage, and inputs the resulting signals to the ECM/PCM. When the HO2S 1/1 begins to deteriorate, the HO2S 1/1 signal response becomes poor. The ECM/PCM forcibly varies the air/fuel mixture to make it leaner and richer, and checks the response speed of the HO2S 1/1. In addition, the ECM/PCM also checks for open in HO2S 1/1 output line.

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM/PCM (terminal No. 72) from the output terminal (terminal No. 4) of the HO2S 1/1. Terminal No. 2 of the HO2S 1/1 is grounded by ECM (terminal No. 49) or PCM (terminal No. 57).

The HO2S 1/1 detects the concentration of oxygen in the exhaust gas; it converts those data to voltage, and inputs the resulting signals to the ECM/PCM. When the HO2S 1/1 begins to deteriorate, the HO2S 1/1 signal response becomes poor. The ECM/PCM forcibly varies the air/fuel mixture to make it leaner and richer, and checks the response speed of the HO2S 1/1. In addition, the ECM/PCM also checks for an open in HO2S 1/1 output line.

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM/PCM (terminal No. 72) from the output terminal (terminal No. 4) of the HO2S 1/1. Terminal No. 2 of the HO2S 1/1 is grounded by ECM (terminal No. 49) or PCM (terminal No. 57).

The ECM/PCM effects air/fuel ratio feedback control in accordance with the signals from the HO2S 1/1. If the HO2S 1/1 has deteriorated, corrections will be made by the HO2S 1/2. DTC P0134 becomes stored in memory if a failure is detected in the above air/fuel ratio feedback control system.

Note. To test HO2S 1/1 response time, ECM/PCM forces fuel mixture alternately lean and rich. If HO2S 1/1 does not respond within predetermined parameters it could be due to HO2S 1/1 problem or fuel injection circuit problem.

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM/PCM (terminal No. 72) from the output terminal (terminal No. 4) of the HO2S 1/1. Terminal No. 2 of the HO2S 1/1 is grounded by ECM (terminal No. 49) or PCM (terminal No. 57). The injector power is supplied from the MFI relay to each injector (terminal No. 4). The ECM/PCM controls the injector by turning the power transistor in the ECM/PCM on and off.

The ECM/PCM checks whether the heater current is within a specified range when heater is energized.

Power is supplied from the MFI relay (terminal No. 1) to the HO2S 1/1 heater. The ECM/PCM (terminal No. 60) controls continuity to the HO2S 1/1 heater by turning the power transistor on and off in the ECM/PCM.

The output signal of the Heated Oxygen Sensor Bank 1, Sensor 1 (HO2S 1/1) is compensated by the output signal of the HO2S 1/2. In addition, the ECM/PCM also checks for an open in HO2S 1/2 output line.

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM/PCM (terminal No. 74) from the output terminal (terminal No. 4) of the HO2S 1/2. Terminal No. 2 of the HO2S 1/2 is grounded by ECM (terminal No. 49) or PCM (terminal No. 57).

The output signal of the Heated Oxygen Sensor Bank 1, Sensor 1 (HO2S 1/1) is compensated by the output signal of the HO2S 1/2. In addition, the ECM/PCM also checks for an open in HO2S 1/2 output line.

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM/PCM (terminal No. 74) from the output terminal (terminal No. 4) of the HO2S 1/2. Terminal No. 2 of the HO2S 1/2 is grounded by ECM (terminal No. 49) or PCM (terminal No. 57).

The output signal of the Heated Oxygen Sensor Bank 1, Sensor 1 (HO2S 1/1) is compensated by the output signal of the HO2S 1/2. In addition, the ECM/PCM also checks for an open in HO2S 1/2 output line.

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM/PCM (terminal No. 74) from the output terminal (terminal No. 4) of the HO2S 1/2. Terminal No. 2 of the HO2S 1/2 is grounded by ECM (terminal No. 49) or PCM (terminal No. 57).

The output signal of the Heated Oxygen Sensor Bank 1, Sensor 1 (HO2S 1/1) is compensated by the output signal of the HO2S 1/2. In addition, the ECM/PCM also checks for an open in HO2S 1/2 output line.

Power is supplied from the MFI relay (terminal No. 4) to the HO2S 1/2 heater. The ECM/PCM terminal No. 27 controls continuity to the HO2S 1/2 heater by turning the power transistor in the ECM/PCM on and off. The ECM/PCM checks whether the heater current is within a specified range when the heater is energized.

The HO2S 2/1 detects the concentration of oxygen in the exhaust gas; it converts those data to voltage, and inputs the resulting signals to the ECM/PCM. When the HO2S 2/1 begins to deteriorate, the HO2S 2/1 signal response becomes poor. The ECM/PCM forcibly varies the air/fuel mixture to make it leaner and richer, and checks the response speed of the HO2S 2/1. In addition, the ECM/PCM also checks for an open in HO2S 2/1 output line.

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM/PCM (terminal No. 71) from the output terminal (terminal No. 4) of the HO2S 2/1. Terminal No. 2 of the HO2S 2/1 is grounded by ECM (terminal No. 49) or PCM (terminal No. 57).

The HO2S 2/1 detects the concentration of oxygen in the exhaust gas; it converts those data to voltage, and inputs the resulting signals to the ECM/PCM. When the HO2S 2/1 begins to deteriorate, the HO2S 2/1 signal response becomes poor. The ECM/PCM forcibly varies the air/fuel mixture to make it leaner and richer, and checks the response speed of the HO2S 2/1. In addition, the ECM/PCM also checks for an open in HO2S 2/1 output line.

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM/PCM (terminal No. 71) from the output terminal (terminal No. 4) of the HO2S 2/1. Terminal No. 2 of the HO2S 2/1 is grounded by ECM (terminal No. 49) or PCM (terminal No. 57).

The ECM/PCM effects air/fuel ratio feedback control in accordance with the signals from the HO2S 2/1. If the HO2S 2/1 has deteriorated, corrections will be made by the HO2S 2/2. DTC P0154 becomes stored in memory if a failure is detected in the above air/fuel ratio feedback control system.

Note. To test HO2S 2/1 response time, ECM/PCM forces fuel mixture alternately lean and rich. If HO2S 2/1 does not respond within predetermined parameters it could be due to HO2S 2/1 problem or fuel injection circuit problem.

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM/PCM (terminal No. 71) from the output terminal (terminal No. 4) of the HO2S 2/1. Terminal No. 2 of the HO2S 2/1 is grounded by ECM (terminal No. 49) or PCM (terminal No. 57).

The ECM/PCM checks whether the heater current is within a specified range when heater is energized.

Power is supplied from the MFI relay (terminal No. 4) to the HO2S 2/1 heater. The ECM/PCM (terminal No. 3) controls continuity to the HO2S 2/1 heater by turning the power transistor on and off in the ECM/PCM.

The output signal of the Heated Oxygen Sensor Bank 2, Sensor 1 (HO2S 2/1) is compensated by the output signal of the HO2S 2/2. In addition, the ECM/PCM also checks for an open in HO2S 2/2 output line.

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM/PCM (terminal No. 73) from the output terminal (terminal No. 4) of the HO2S 2/2. Terminal No. 2 of the HO2S 2/2 is grounded by ECM (terminal No. 49) or PCM (terminal No. 57).

The output signal of the Heated Oxygen Sensor Bank 2, Sensor 1 (HO2S 2/1) is compensated by the output signal of the HO2S 2/2. In addition, the ECM/PCM also checks for an open in HO2S 2/2 output line.

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM/PCM (terminal No. 73) from the output terminal (terminal No. 4) of the HO2S 2/2. Terminal No. 2 of the HO2S 2/2 is grounded by ECM (terminal No. 49) or PCM (terminal No. 57).

The output signal of the Heated Oxygen Sensor Bank 2, Sensor 1 (HO2S 2/1) is compensated by the output signal of the HO2S 2/2. In addition, the ECM/PCM also checks for an open in HO2S 2/2 output line.

A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM/PCM (terminal No. 73) from the output terminal (terminal No. 4) of the HO2S 2/2. Terminal No. 2 of the HO2S 2/2 is grounded by ECM (terminal No. 49) or PCM (terminal No. 57).

The output signal of the Heated Oxygen Sensor Bank 2, Sensor 1 (HO2S 2/1) is compensated by the output signal of the HO2S 2/2. In addition, the ECM/PCM also checks for an open in HO2S 2/2 output line.

Power is supplied from the MFI relay (terminal No. 4) to the HO2S 2/2 heater. The ECM/PCM terminal No. 26 controls continuity to the HO2S 2/2 heater by turning the power transistor in the ECM/PCM on and off. The ECM/PCM checks whether the heater current is within a specified range when the heater is energized.

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

The injector power is supplied from the MFI relay (terminal No. 4) to each injector (terminal No. 1). The PCM controls the injector by turning the power transistor in the ECM/PCM on and off.

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

The injector power is supplied from the MFI relay (terminal No. 4) to each injector (terminal No. 1). The ECM/PCM controls the injector by turning the power transistor in the ECM/PCM on and off.

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

The injector power is supplied from the MFI relay (terminal No. 4) to each injector (terminal No. 1). The PCM controls the injector by turning the power transistor in the ECM/PCM on and off.

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

The injector power is supplied from the MFI relay (terminal No. 4) to each injector (terminal No. 1). The PCM controls the injector by turning the power transistor in the ECM/PCM on and off.

The fuel temperature sensor converts the fuel temperature to a voltage. The ECM/PCM detects the fuel temperature in the fuel tank with this output voltage.

5-volt voltage is applied to the fuel temperature sensor output terminal (terminal No. 3) from the ECM (terminal No. 96) or PCM (terminal No. 51) through a resistor in the ECM/PCM. The fuel temperature sensor output voltage increases when the resistance increases and decreases when the resistance decreases. The ground terminal (terminal No. 1) is grounded to the vehicle body.

The fuel temperature sensor converts the fuel temperature to a voltage. The ECM/PCM detects the fuel temperature in the fuel tank with this output voltage.

5-volt voltage is applied to the fuel temperature sensor output terminal (terminal No. 3) from the ECM (terminal No. 96) or PCM (terminal No. 51) through a resistor in the ECM/PCM. The fuel temperature sensor output voltage increases when the resistance increases and decreases when the resistance decreases. The ground terminal (terminal No. 1) is grounded to the vehicle body.

The fuel temperature sensor converts the fuel temperature to a voltage. The ECM/PCM detects the fuel temperature in the fuel tank with this output voltage.

5-volt voltage is applied to the fuel temperature sensor output terminal (terminal No. 3) from the ECM (terminal No. 96) or PCM (terminal No. 51) through a resistor in the ECM/PCM. The fuel temperature sensor output voltage increases when the resistance increases and decreases when the resistance decreases. The ground terminal (terminal No. 1) is grounded to the vehicle body.

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

The injector power is supplied from the MFI relay (terminal No. 4) to each injector (terminal No. 1). The ECM/PCM controls the injector by turning the power transistor in the ECM/PCM on and off.

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

The injector power is supplied from the MFI relay (terminal No. 4) to each injector (terminal No. 1). The ECM/PCM controls the injector by turning the power transistor in the ECM/PCM on and off.

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

The injector power is supplied from the MFI relay (terminal No. 4) to each injector (terminal No. 1). The ECM/PCM controls the injector by turning the power transistor in the ECM/PCM on and off.

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

The injector power is supplied from the MFI relay (terminal No. 4) to each injector (terminal No. 1). The ECM/PCM controls the injector by turning the power transistor in the ECM/PCM on and off.

The Knock Sensor (KS) converts the vibration of the cylinder block into a voltage and outputs it. If there is a malfunction of the KS, the voltage output will not change. The ECM/PCM checks whether the voltage output changes.

The KS sends a signal voltage to the ECM (terminal No. 91) or PCM (terminal No. 90).

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

The CKP sensor power terminal (terminal No. 3) is supplied from the MFI relay (terminal No. 4). Terminal No. 1 of the CKP sensor is grounded by ECM (terminal No. 34) or PCM (terminal No. 16). A 5-volt voltage is applied on the CKP sensor output terminal (terminal No. 2) from ECM (terminal No. 43) or PCM (terminal No. 45). The CKP sensor generates a pulse signal when the output terminal is opened and grounded.

The Camshaft Position (CMP) sensor functions to detect the top dead center position of cylinder No. 1 and to convert that data to pulse signals that are input to the ECM/PCM. When the engine is running, the CMP sensor outputs a pulse signal. The ECM/PCM checks whether pulse signal is input while the engine is cranking.

The CMP sensor power is supplied from the MFI relay (terminal No. 4) to CMP sensor (terminal No. 6). Terminal No. 7 of the CMP sensor is grounded by ECM (terminal No. 34) or PCM (terminal No. 16). A 5-volt voltage is applied on the CMP sensor output terminal (terminal No. 5) from the ECM (terminal No. 50) or PCM (terminal No. 56). The CMP sensor generates a pulse signal when the output terminal is opened and grounded.

When the EGR solenoid switches from off to on while the engine is running, EGR gas flows. The ECM/PCM checks how the EGR gas flow signal changes.

To judge if there is an open in the EGR solenoid drive circuit, ECM/PCM measures the surge voltage of the EGR solenoid coil. The ECM/PCM drives the EGR solenoid. After the solenoid is turned off, the ECM/PCM 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/PCM controls the EGR solenoid ground by turning the power transistor in the ECM/PCM on and off.

The signal from the rear Heated Oxygen Sensor (HO2S) differs from the front HO2S. That is because the catalytic converter purifies exhaust gas. When the catalytic converter has deteriorated, the signal from the front HO2S becomes similar to the rear HO2S. The ECM/PCM compares the output of the front and rear HO2S signals.

The signal from the rear Heated Oxygen Sensor (HO2S) differs from the front HO2S. That is because the catalytic converter purifies exhaust gas. When the catalytic converter has deteriorated, the signal from the front HO2S becomes similar to the rear HO2S. The ECM/PCM compares the output of the front and rear HO2S signals.

ECM/PCM detects if EVAP purge solenoid valve is stuck open and if EVAP Ventilation (VENT) solenoid valve is stuck closed by pressure change in fuel tank. EVAP purge solenoid valve stuck open condition is judged through monitoring leak of EVAP control system. EVAP VENT solenoid valve stuck closed condition is judged after 20 seconds of end of monitoring leak of EVAP control system, or of usual operation of EVAP purge solenoid from on to off.

To judge if there is a leak in the fuel system, ECM/PCM measures the change of the pressure inside the fuel tank. The ECM/PCM turns on the EVAP Ventilation (VENT) solenoid to shut off the EVAP canister outlet port. Then the EVAP 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 EVAP purge solenoid is turned OFF and the fuel system vacuum is maintained at 0.29 psi (2 kPa). The ECM/PCM determines if there is a 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.

To judge if there is an open circuit in the EVAP purge solenoid drive circuit, ECM/PCM measures the surge voltage of the EVAP Ventilation (VENT) solenoid coil. The ECM/PCM drives the EVAP purge solenoid for 30 milliseconds. After the solenoid is turned off, the ECM/PCM will check if the solenoid coil produces a surge voltage of 2 volts or more.

Power to the EVAP purge solenoid power is supplied from the MFI relay (terminal No. 4). The ECM/PCM controls ground of EVAP purge solenoid by turning the power transistor in the ECM/PCM on and off.

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

The EVAP VENT solenoid power is supplied from the MFI relay (terminal No. 4). The ECM/PCM controls the EVAP VENT solenoid ground by turning the power transistor in the ECM/PCM on and off.

To judge if the Fuel Tank Differential Pressure (FTDP) sensor is defective, the ECM/PCM monitors the FTDP sensor output voltage. Based on the check conditions and judgment criteria, the ECM/PCM judges if the FTDP sensor output voltage is normal.

A 5-volt voltage is supplied to the power terminal of the FTDP sensor (terminal No. 3) from the ECM (terminal No. 42) or PCM (terminal No. 46). The sensor ground terminal (terminal No. 2) is grounded by the ECM (terminal No. 49) or PCM (terminal No. 57). A voltage proportional to the pressure in the fuel tank is sent from the output terminal of the FTDP sensor (terminal No. 1) to the ECM (terminal No. 93) or PCM (terminal No. 92.)

To judge if the Fuel Tank Differential Pressure (FTDP) sensor is defective, the ECM/PCM monitors the FTDP sensor output voltage. Based on the check conditions and judgment criteria, the ECM/PCM judges if the FTDP sensor output voltage is normal.

A 5-volt voltage is supplied to the power terminal of the FTDP sensor (terminal No. 3) from the ECM (terminal No. 42) or PCM (terminal No. 46). The sensor ground terminal (terminal No. 2) is grounded by the ECM (terminal No. 49) or PCM (terminal No. 57). A voltage proportional to the pressure in the fuel tank is sent from the output terminal of the FTDP sensor (terminal No. 1) to the ECM (terminal No. 93) or PCM (terminal No. 92.)

To judge if the Fuel Tank Differential Pressure (FTDP) sensor is defective, the ECM/PCM monitors the FTDP sensor output voltage. Based on the check conditions and judgment criteria, the ECM/PCM judges if the FTDP sensor output voltage is normal.

A 5-volt voltage is supplied to the power terminal of the FTDP sensor (terminal No. 3) from the ECM (terminal No. 42) or PCM (terminal No. 46). The sensor ground terminal (terminal No. 2) is grounded by the ECM (terminal No. 49) or PCM (terminal No. 57). A voltage proportional to the pressure in the fuel tank is sent from the output terminal of the FTDP sensor (terminal No. 1) to the ECM (terminal No. 93) or PCM (terminal No. 92.)

To judge if there is a leak or clog in the fuel system, ECM/PCM measures the change of the pressure inside the fuel tank. The ECM/PCM turns on the EVAP Ventilation (VENT) solenoid to shut off the EVAP canister outlet port. Then the EVAP 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 EVAP purge solenoid is turned OFF and the fuel system vacuum is maintained at 0.29 psi (2 kPa). The ECM/PCM determines if there is a 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.

To judge if there is a leak in the fuel system, ECM/PCM measures the change of the pressure inside the fuel tank. The ECM/PCM turns on the EVAP Ventilation (VENT) solenoid to shut off the EVAP canister outlet port. Then the EVAP 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 EVAP purge solenoid is turned OFF and the fuel system vacuum is maintained at 0.29 psi (2 kPa). The ECM/PCM determines if there is a 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.

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

The fuel level drive signal is input in ECM (terminal No. 97) or PCM (terminal No. 60).

The Vehicle Speed Sensor (VSS) converts vehicle speed into pulse signals and inputs them to the ECM. The VSS 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 VSS output terminal (terminal No. 3) from the ECM (terminal No. 80). The VSS generates a pulse signal when the output terminal is opened and grounded.

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 Idle Air Control (IAC) system, the actual engine speed will not be identical to the target engine speed. The ECM/PCM checks the difference between the actual engine speed and the target engine speed.

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

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 Idle Air Control (IAC) system, the actual engine speed will not be identical to the target engine speed. The ECM/PCM checks the difference between the actual engine speed and the target engine speed.

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

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

A battery positive voltage is applied to the PSP switch output terminal (terminal No. 1) from the ECM (terminal No. 54) or PCM (terminal No. 52) through a resistor in the ECM/PCM.

The Manifold Differential Pressure (MDP) sensor outputs a voltage which corresponds to the negative pressure in the intake manifold. The ECM/PCM checks whether the voltage output by MDP sensor is within a specified range.

A 5-volt voltage is applied on the MDP sensor power terminal (terminal No. 3) from the ECM (terminal No. 42) or PCM (terminal No. 46). The ground terminal (terminal No. 2) is grounded by the ECM (terminal No. 49) or PCM (terminal No. 57). A voltage proportional to the pressure in the intake manifold plenum is sent from the MDP sensor output terminal (terminal No. 1) to the ECM (Terminal No. 92) or PCM (terminal No. 91).

When the generator field coils are controlled, the generator FR terminal inputs signal to the ECM/PCM. The ECM/PCM detects the generator output with the input signal, and controls the Idle Air Control (IAC) motor according to the generator output.

The ECM (terminal No. 52) or PCM (terminal No. 54) applies a battery positive voltage into the generator FR terminal (terminal No. 4) through resistance inside the unit.

The ECM/PCM checks for an 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 DTCs.

ECM/PCM monitors the communication condition with the immobilizer ECU and the message from the immobilizer ECU. When an abnormality is found, ECM/PCM prevents engine start.

See also:
• WIRING DIAGRAMS
• SYSTEM & COMPONENT TESTING