Q: How do I replace the headlight bulb in a Mercury Mariner?
A: First of all, ensure that the ignition and Headlight switches are turned off. Next, raise the hood. After that, unplug the electrical connector from the headlight assembly for earlier models like 2007. Then remove the rubber boot and bulb retainer spring. Remove the bulb without touching its glass part. Insert a new bulb ensuring that its metal tabs align with the plastic base. Push the bulb till it is fully seated into position. Reattach the rubber book and spring back onto their previous positions. Now plug in the connector again. Close up by testing headlights and closing the hood again, for model years 2008 as well as subsequent versions repeat the above steps but twist counterclockwise then pull out the bulb after testing headlights close up by closing the hood again.