Other Control Functions

1. Starting Control
When the engine is started, the ECM provides a rich mixture.
2. Fuel Pump Control
a. When the ignition switch is initially turned on, the ECM supplies ground to the main relay which supplies current to the fuel pump for two seconds to pressurize the fuel system.
b. When the engine running, the ECM supplies ground to the main relay which supplies current to the fuel pump.
c. When the engine is not running and the ignition is on, the ECM cuts ground to the main relay which cuts current to the fuel pump.
3. Fuel Cut-off Control
a. During deceleration with the throttle valve closed, current to the injectors is cut off to improve fuel economy at speeds over 1500 rpm.
b. Fuel cut-off action also takes place when engine speed exceeds 6300 rpm, regardless of the position of the throttle valve to protect the engine from over-running.
4. A/C Compressor Clutch Relay
When the ECM receives a demand for cooling from the air conditioning system (compressor control unit), it delays the compressor from being energized, and enriches the fuel mixture to assure smooth transition to the A/C mode.
5. Purge Cut-off Solenoid Valve
When the coolant temperature is below 167°F (75°C), the ECM supplies a ground to the purge cut-off solenoid valve which cuts vacuum to the purge control valve.
6. Intake Control Solenoid Valve
When the engine speed is below 3500 rpm, the ECM supplies ground to the Intake Control Solenoid Valve. This opens the solenoid valve sending intake manifold vacuum to the intake control diaphragm.
7. EGR Control Solenoid Valve (EGR CSV)
When the EGR is required for control of oxides of nitrogen (NOx) emissions, the ECM supplies ground to the EGR CSV which supplies regulated vacuum to the EGR valve.
8. Alternator Control
The system controls the voltage generated at the alternator according to the electric load and drive mode, and reduces the engine load to improve the fuel economy.
9. Bypass Control Solenoid Valve (BPCSV) (USA: SE model, CANADA: SE, Ex-R models)
When the engine rpm is below 5000 rpm the BPCSV is activated by a signal from the ECM, intake air flows through the long intake path, producing high torque. At speeds higher than 5000 rpm, the solenoid valve is deactivated by the ECM, and intake air flows through the short intake path in order to reduce the resistance in airflow.