[V8] Mystery of headlights

[Professor GT gmail]

As kneale and others have stated, repair/replace the overheated parts, and them add a relay for the lights. It's pretty amazing that it took so long for various manufacturers (many of them) to finally add a relay for the lights. The current flow causes heat and that causes the failures you have experienced. AND the loss of headlight performance is caused by, you guessed it - voltage drop!

When you wire in the relay, put it out by the lights so the hight current circuit circuit is a short run, and the low current control circuit (will be approx 120ma with a standard ISO relay), will be the longer run up through the switch. Having low current going through the switch will eliminate the problem you experienced for good. In fact, I never realized that the system did not have a relay, so this will be added to my to-do list, as I really don't want to go through the expense of replacing the switch or the dimmer.
With the shorter high current run to the lights they will burn brighter as well (less voltage drop in the circuit to and from the loads). The relay ideally should be in an enclosure to keep the water away, or at least tucked up out of the way in a location that keeps it protected. If you want, email me and I will draw up a diagram for you to wire in the relay, using the factory schematic.

Thanks,

ProfessorGT
CavalloGT at gmail.com
(Sent from my iPhone4)