Air Switching/Relief Valve
This valve directs air injection flow to either the location near exhaust ports or to downstream injection point. The valve also serves as a relief valve at high engine speeds.
A vacuum signal, from Coolant Vacuum Switch (CVS), causes switching valve to open. This routes air pump airflow into exhaust ports. When CVS shuts off vacuum to the switching valve, a bleed orifice in the vacuum hose allows vacuum signal to go to zero, causing the switching valve to route air pump air to downstream injection point.