headlights are dim. why

Hello, do you have the original Nissan bulbs in the vehicle or have they been modified to non original Nissan - non original style? Are the lamp assemblies tarnished and foggy visibly? If the wrong bulbs are installed - restore the vehicle to factory condition. If the lamps are tarnished, you may be able to see a repair shop to have them "restored" - where the bad finish is buffed off and a new clear coat is added. This is depending on whether or not the lamps have deteriorated past a certain point. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops