Melted headlight bulb connector - Cause?

Replaced my badly faded original headlights with some "Eagle Eyes" brand replacements from Amazon about 4 months ago. Last night the passenger side started flickering then cut out. I assumed a bad bulb and went to replace it this morning and found the connector had melted. What would cause this? I was running standard wattage Philips bulbs, not any sort of crazy blue high wattage bulbs.

the fact that it melted and not blow a fuse means it wasn't amperage. a loose connection causes arcing and heat and melting but the amperage draw doesn't increase. usually the spring load in the connector gets bent or weak so as to not make a tight contact or dirty.

Corroded and/or loose connection -> increased resistance -> increased voltage drop across the connection -> increased heat

This is particularly a problem with upgraded wattage bulbs, as the wiring seems to be pretty carefully sized for stock. Are "Eagle Eyes" a stock wattage bulb or high output?

Either way... moisture gets in and...

Eagle Eyes was just the aftermarket brand of the entire light housing. I had used philips standard wattage bulbs. I'm thinking that perhaps it was just a loose connection as jetlagmech suggested. Now that I look closer it does look loose in there for the two pieces that would pinch the prong on the bulb. Maybe it was loose from the start or maybe i bent it somehow slightly during the initial install.

Yup... can happen.

The stock wiring is barely up to the job of handling stock high-beam current... then add a little bit of extra looseness or corrosion and she melts.

Looking at your picture, It also looks as if there is enough room to get on the wrong side of the actual connector - i.e., the hole looks larger than the pin inside. Hit the pin inside, you're golden. Hit beside the connector, you'll have initial connection - not tight - heat builds, oxidation increases, resistance increases, heat increases till you get what you describe.

As sharp and precise as we think the German engineers are, their accountants seem to have the sharper pencil. Every BMW M/C (prior to LED and Zenon) has undersized headlight wiring. It's a laugh. But saves money. (and fits better within handlebars) In the relatively short wiring on M/C, the wiring produces about a volt of drop to the headlights - dimming them as one would expect. Pop in higher watt bulbs, and connectors and/or switchgear melt on a regular basis. Most owners feed a large wire from the batt and use the headlight switch gear to trip a relay - and rewire from the relay to the headlamp. Brighter headlights, and no fuss with switchgear or connectors.

So, Vince is spot on. Stock wiring is barely up to the job. A German thing. Anything but a tight, clean connection will cause the type of heat necessary to melt the connector.

frank

I had the EXACT same thing happen to me, drivers side, Eagle Eyes and all. I ordered a set of Dorman headlight pigtails from Amazon. Cut the old socket off and butt connectored the new one on - works great!

You get two in the set so if the passengers side fails you are good to go. I also eliminated my DRL so as to not press my luck in the future.

Another trick when you're replacing the plug, or even when working in there replacing a bulb, is to add a little dielectric paste. It helps to keep moisture out, and generally reduces corrosion potential.

You can even buy little packets of it at many auto parts stores, marked as "bulb grease" if you don't want to buy a tube of it.

Same thing happened to me. Took it to a mechanic who actually swapped high/low beam wiring per side--so that one side would be on hi and when you hit the brights they would swap, lol... That was when my wife and I were both working and didn't have time to deal w/ it.
Anyway yeah, add dielectric grease when you put the connectors back together. And don't swap the wiring, lol!

I have this problem walk thru the door about twice a month. Just replace the plug and out the door. This is a very common problem that appears more common with any small terminal headlamp bulbs. Not so much on the big sealed beam bulbs unless there is a lot of corrosion present. Put dielectric grease on the connector but that's about all you can do.