My 2011 F 150 XLT 3.5 ecoboost. The left turn signal blinks three times at the normal pace then cuts off. All the exterior lights are working, what else could be the issue. confused

 

That is a feature built into your truck, it's for changing lanes, when you just want to change lanes, just touch the lever and lightly push in the direction you want to go. For a full turn just push a little more and it stay on until you make the turn.