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Fluid Pressure Sensor/Switch: Description and Operation

Description
A pressure sensitive switch is screwed through the rear face of the valve body assembly into the direct clutch oil passage. This switch is closed (grounded) in all but direct drive and reverse, since there is no oil pressure in this passage in Neutral, First or Second gear. The pressure switch is connected by a wire to a transmission connector and hence through an engine solenoid valve to the distributor and engine thermoswitch. When this circuit is grounded (switch closed), spark advance is retarded.

When the transmission shifts to high gear (or reverse), oil pressure in the direct clutch passage will open the switch and circuit so that the transmission will no longer affect the vacuum advance of the distributor.

Line Pressure Regulator
Regulates line pressure according to pump speed and engine torque.