Every time you wash the car or it rains, you may notice condensation, moisture or even water build-up inside the headlight assembly. This simply means the seam of the headlight has been compromised or perhaps it has sustained damage to the housing. Most often, you can repair the assembly without having to replace it. Since there are several procedures in place for removing the assemblies, depending on make and model, a good repair manual specific to your vehicle will be helpful. If the moisture is ignored, the wiring and light sockets can sustain damage and further repairs will be required.
Removing the Headlight Assembly
Since each make and model often requires a variety of different procedures to remove the headlight assembly, referring to a repair manual is recommended. Owners manuals these days are often not geared towards informing owners how-to procedures for self-repairs.
Most often, headlight assemblies are retained by two upper bolts or retaining rods. Removing radiator covers can be required to access the retaining devices. Some models even require the front grill to be removed in order to allow the headlight assembly to be disassembled from the vehicle.
Once the retaining devices are removed (and the grill, if required), you'll be able to pull the assembly forward, unplug the light sockets from the assembly and then remove it.
Headlight Assembly and Socket Maintenance
Inspect the headlight assembly for visible cracks or holes. Because the assemblies are glued together at a seam holding the front lens to the assembly unit, often times the seal has simply been compromised from exposure.
With the assembly removed, inspect the lights and sockets. If moisture has compromised them, they may have dark or black burn marks from shorting out electrically. If so, cut the wires of the sockets and replace them with new ones. Use butt connectors that feature heat-shrinking to seal the connections. Be sure to colour coordinate the wires when reconnecting.
To remove the moisture from the headlight assembly, a number of different methods can be employed. Placing it in the sun will dry the moisture as will using a hair dryer. Another unconventional method is to bake the assembly in the oven wrapped in a towel to soften and inevitably reseal the leaking seam. Since the assembly is removed from the vehicle, it is still highly recommended to reseal it with a permatex compound or a silicone sealant.
Run a small bead along the entire perimeter of the seam and then allow it time to cure and dry before replacing.
Even if you're replacing the headlight assembly with a new one, it's a wise idea to seal the seam with the compound to avoid future problems.
Socket Covers and Re-installation
Inspect the black rubber socket covers that protect the sockets from inclement weather conditions, while reassembling the headlight assembly. This is another area where the moisture can get into the headlight assembly if the covers are compromised or damaged. A black permatix compound can help repair the covers, or you could simply replace them if necessary. You don't want to seal the covers to the assembly because you'll complicate the headlight replacement procedure in the future.
Once replaced or repaired, if required, follow the removal procedure for the headlight assembly in reverse to reinstall. Be sure to test the bulbs for proper operation before reassembling the grill or any other components that needed to be removed in order to remove the assembly or access the light bulbs.