Other Control Functions
Starting ControlWhen the engine is started, the Engine Control Module (ECM) provides a rich mixture by increasing Fuel Injector duration.
Fuel Pump Control
^ When the ignition switch is initially turned on, the ECM supplies ground to the Main Relay that supplies current to the Fuel Pump for two seconds to pressurize the fuel system.
^ When the engine is running, the ECM supplies ground to the Main Relay that supplies current to the Fuel Pump.
^ When the engine is not running and the ignition is on, the ECM cuts ground to the PGM-Fl Main Relay which cuts current to the Fuel Pump.
Fuel Cut-off Control
^ To improve fuel economy, current to the Fuel Injectors is cut off during deceleration with the throttle valve closed, at speeds over 914 rpm, in no-load conditions in which the headlights, blower fan, rear defogger, radiator fan and air conditioner are not operating.
^ Fuel cut-off action also takes place when a maximum engine speed of 8100 rpm is exceeded, regardless of the position of the throttle valve, to protect the engine from over-revving.
A/C Compressor Clutch Relay
When the ECM receives a demand for cooling from the air conditioning system, it delays the compressor from being energized, and enriches the mixture to assure smooth transition to the A/C mode.
Evaporative Emission (EVAP) Purge Control Solenoid Valve
When the engine coolant temperature is below 75°C (167°F), the ECM supplies a ground to the EVAP Purge Control Solenoid Valve which cuts vacuum to the EVAP Purge Control Diaphragm Valve.
Alternator Control
The system controls the voltage generated at the alternator in accordance with the electrical load and drive mode, which reduces the engine load to improve the fuel economy.
Lock-up Control Solenoid Valve (A/T)
The vehicle speed and throttle position sensor inputs to the Engine Control Module (ECM) are used to send an on/off voltage signal to the Lock-up Control Solenoid Valve for precise timing of the Torque Converter Lock-up System.