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What Is A Transmission Solenoid?

Everything that happens inside an automatic transmission happens because of hydraulic pressure. There are circuits machined throughout the inside of all automatic transmissions that carry fluid under intense pressure to different compartments to cool, lubricate and apply pistons. Those pistons apply clutch plates for reverse, 1st, 2nd, 3rd, 4th, 5th, 6th and recently for 7th, 8th, 9th and 10th gear.

The component that causes the fluid to flow into the respective circuits at the correct time is a solenoid. A transmission solenoid is an electro-hydraulic valve that controls fluid flow into and throughout an automatic transmission. Solenoids can be normally open or normally closed. They operate via a voltage or current supplied via the transmission's computer or controller. Transmission solenoids are usually installed in a transmission valve body, transmission control unit or transmission control module.

It is interesting to know your refrigerator's ice maker, dishwasher and washing machine use the same technology.....solenoids.