Circuit/System Description

The secondary air injection (AIR) system aids in the reduction of hydrocarbon emissions during a cold start. The electric air pump forces fresh air into the exhaust stream in order to accelerate the catalyst operation. An AIR system pressure sensor is used to monitor the air flow from the AIR pump. The Engine Control Module (ECM) supplies 5 V to the 5 V reference circuit and supplies a ground to the low reference circuit. The sensor provides a signal voltage to the ECM relative to the pressure changes within the AIR system.

Ignition voltage is supplied directly to the secondary air injection pump relay. The Engine Control Module (ECM) controls the relay by grounding the control circuit, which activates the AIR pump relay. With the relay contacts closed, battery voltage is supplied to the AIR pump.