Output Components

The fuel control system consists of the ECU outlined previously and various input and output components. The output components change various modes of operation based on signals from the ECU. The following is a list and description of the output components:


System Power (Latch) Relay

Initially energized during engine start up, this relay remains energized 3 to 5 seconds after engine shutdown. This permits the ECU to extend the idle speed actuator for the next start up.



Fuel Pump Control Relay

Battery voltage is applied to this relay whenever the ignition switch is turned to the On position. The ECU then completes the ground to the circuit, energizing the relay, which in turn activates the fuel pump.



Fuel Injector

The ECU receives data from the various input sensors during all engine operating modes. Injection duration is based on these inputs and is controlled by the ECU, which energizes and de-energizes the injector solenoid as required.



EGR Valve/Canister Purge Solenoid

This solenoid controls the vacuum source to both the EGR valve and vapor canister. When de-energized, vacuum is applied to both components. When energized by the ECU, this solenoid prevents vacuum from reaching the EGR valve and vapor canister. Conditions when this solenoid will be energized include engine warm-up, curb idle, wide open throttle and rapid acceleration or deceleration.



Idle Speed Actuator (ISA) Motor

Located on the throttle body, this device controls idle speed and deceleration throttle stop angles. The ECU controls the ISA motor by applying appropriate voltage outputs to it, thereby producing the idle speed or throttle stop angles required for specific engine operating conditions.



Ignition Power Module

Based on input data received, the ECU triggers the ignition coil via this module.



Compressor Clutch Relay

This relay controls the engagement and disengagement of the compressor clutch based on voltage signals received from the ECU.



Up-Shift Indicator Lamp

Used on manual transmission equipped vehicles, this lamp illuminates when the ignition switch is turned On, and is turned Off when engine start up occurs. The lamp will illuminate during driving when engine speed and load are within specified values. The ECU will turn off the lamp if a shift of gears is not performed within 3-5 seconds of lamp illumination.