Secondary Air Valves & EVR (which has nothing to do with secondary air, but is a solenoid vacuum valve similar to the Thermactor Air Bypass & Thermactor Air Diverter, and is usually mounted beside them)
TAB & TAD solenoids should read 50-100 Ohms; each should hold vacuum applied to the source (farthest) nipple until 12V is applied across the solenoid terminals, at which point it should vent to the other nipple.
TAD pigtailTAB pigtailSee also:
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