This 2012 Ford Fusion came in with the complaint that the driver’s side low beam headlight id not work. The customer stated that she had the bulb changed a few days earlier but it has failed again. The area is a little confined but the headlamp assembly does not need to be removed in order to perform this repair. Looking behind the driver’s side headlight and past the air filter housing the black rubber cap can be seen. It is very important that this round cover not be lost or forgotten about. It seals out dirt and water.
Placing my arm behind the headlamp and in front of the air filter housing was the most effective way for me to get to the bulb.
The round rubber cap that seals the rear of the headlamp assembly.
Disconnecting the harness from the bulb while it was still installed was too difficult given the size of my hands and forearms.
So I removed and installed the bulb with the harness connected to it. You just have to be very careful to not touch anything to the glass portion of the bulb. Including fingers.
Disconnecting the harness from the bulb revealed the real problem. The terminal in the harness has overheated and was no longer making sufficient contact with the matching terminal in the bulb.
Cut the old one out and spliced in a new harness. Another brand new bulb was also installed after replacing the harness connector. The old bulb already had signs of arc damage on the terminals and that would have adversely affected the new harness. ALWAYS install a new electrical component when a harness is replaced for heat damage. If not you will be doing it again.
And the headlight is back working.