Solenoid Control Switch
Switch, located at transmission, opens or closes in relation to car speed (automatic transmission) or gear range (manual transmission). At speeds above 25-30 MPH (auto, trans.) or in high gear (manual trans.) the switch opens and breaks the ground circuit to the solenoid vacuum valve. At speeds under 25 MPH (auto, trans.) or when in lower gear ranges (manual trans.) the switch closes and completes the ground circuit to the solenoid vacuum valve. On automatic transmissions, switch is operated by transmission oil pressure. On manual transmissions, switch is operated by shifter shaft.