Power windows: It activates the internal mechanism that rolls the windows up and down.
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It may be manually activated with a window crank, or electrically activated with just a switch. Cranks are always attached to the door itself, while switches may be either on the door or the central console.
Tensioner pulley shit the bed and the belt frayed and blew off. Put a new pulley and belt on and after doing so, the power windows and locks, gauge clusters, and 4 wheel drive electronic swith quit working. It's a 2003 chevy silverado.