What is the mirror puddle light and where is it located? 

The mirror puddle light helps you see what you’re stepping into when you get out of your car.  When you or your passenger opens the door, the light turns on, illuminating the ground beside the door.  Then you can if you are stepping into a puddle, thick mud, a patch of ice, or anything else that might ruin your day.  Since these lights are so helpful, they are sometimes called courtesy lights.  Some cars have courtesy lights built into the doors, but many trucks and SUVs have courtesy lights mounted on the underside of the side view mirrors. 

How do I know if my ­­­­ mirror puddle light needs to be replaced?                

Puddle lights can develop more or less the same problems as any of the other lights on your vehicle.  The lenses can be chipped or scratched, and can become faded and cloudy.  Although the puddle lights aren’t as exposed as the headlights, they can also be damaged in an accident or by road debris.  They can also simply burn out.  If your puddle lights aren’t turning on, or aren’t as bright as they used to be, then it might be time to replace them.  Consider it a courtesy to yourself. 

Can I replace the mirror puddle light myself?  

In most cases, replacing a puddle light is quite easy, and can be completed by even a novice do-it-yourselfer.  The puddle light might be held into the mirror by screws, or it might simply be clipped in.  Remove any fasteners.  Then you can pry the light out.  You’ll need a thin tool to pry on the small light.  A household butter knife can be surprisingly useful here.  Once the light is out, you can just twist the bulb socket out of the light.  Then you can just twist the socket into the new light, push the light into place, and reinstall any fasteners.