Other Control Functions

A/C COMPRESSOR CLUTCH RELAY
When the Engine Control Module (ECM) receives a demand for cooling from the air conditioning system (compressor control unit), 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) and air conditioner OFF the ECM supplies a ground to the EVAP purge control solenoid valve which cuts vacuum to the EVAP purge control diaphragm valve.

EXHAUST GAS RECIRCULATION (EGR) CONTROL SOLENOID VALVE
When the EGR is required for control of oxides of nitrogen (NOx) emissions, the ECM supplies ground to the EGR control solenoid valve which supplies regulated vacuum to the EGR valve.

FUEL INJECTION AIR (FIA) CONTROL SOLENOID VALVE
When the engine rpm is between 1,300 and 4,500 rpm, the ECM supplies ground to the FIA control solenoid valve, sending intake air to the fuel injectors.

INTAKE AIR RESONATOR (IAR) CONTROL SOLENOID
When the engine rpm is below 2,900 rpm, the IAR control solenoid valve is deactivated by the ECM and the resonator is bypassed. Between 2,900 rpm and 3,700 rpm (mid-range), the solenoid valve is energized by the ECM and intake air flows from the IAR, eliminating a low spot in engine torque output.

VARIABLE VALVE TIMING AND LIFT ELECTRONIC CONTROL (VTEC)
Under proper conditions the ECM will engage the VTEC system and provide increased valve lift and duration for improved performance blended with good driveablity and fuel economy.