The Secondary Air Injection (AIR) System reduces
exhaust emissions following initial engine start up.
This occurs when the engine Start-up coolant
temperature is between 3-50°C (37-122°F) and the
intake air temperature (IAT) is more than 1°C
(32°F). The AIR pump will operate until Closed
Loop operation is achieved.
The powertrain control module (PCM) activates the
AIR system by suppling a ground to the AIR pump
relay and AIR solenoid relay simultaneously. This
action closes the internal contacts of the AIR pump
relay, energizing the AIR pump and also closes the
internal contacts of the AIR solenoid relay,
energizing the AIR solenoid, opening the shut-off
valve. The AIR pump forces pressurized fresh air
into the pipes/hoses and past the check valve into
the exhaust manifold, accelerating catalyst
operation. When the AIR system is inactive, the
AIR shut-off valve prevents airflow in either direction.
The AIR diverter valve has an electronic solenoid
mounted on the valve. The resistance of the
solenoid is 4-7 ohms and the current draw is 2-3.5
amps. The solenoid opens the shut-off valve when
battery voltage is applied to the valve. Once
opened, pressurized air from the AIR pump flows
past the check valve and is directed into the
exhaust manifold through an outlet pipe. The
shut-off valve prevents fresh air from being drawn
into the exhaust manifold by providing a positive
seal when the AIR system is inactive. The solenoid,
valve, and outlet pipe are serviced as an assembly.
Secondary Air Injection and Valve Operation