S10/T10 Blazer 4WD L4-119 1.9L VIN A 2-BBL (1983)
Throttle Full Open Switch: Description and Operation
This switch is mounted on the same bracket as the idle position switch. Like the idle position switch, this switch senses intake manifold vacuum and
sends an electrical signal to the ECM when the engine is at WOT. This information is used by the ECM to distinguish between closed throttle (idle) and
wide open throttle positions.