Instructions
Power on your PS3 and navigate to the "Settings" menu on the XMB dashboard.
Select "Accessory Settings" from the menu by highlighting it and pressing the "X" button.
Scroll through the options in "Accessory Settings" until you get to "Controller Vibration Function." Press the "X" button.
Use the D-Pad or Left Stick to toggle the Vibration Function to "On," then press the "X" button. You can activate the vibration function during gameplay as well. Press and hold the PS button, then select "Controller Settings" and press the "X" button. Highlight "Vibration Function" and press the "X" button, then use the D-Pad or Left Stick to toggle the function to "On" and press "X." Press the PS button to resume gameplay.