headlight high beam fuse melted

[Michael]

I decided to clean my fuses today. I noticed the high beam fuse had been hot to the point of melting sometime in the past. I turned my lamps on and checked. The fuse will become hot pretty quickly. The low beam fuse is fine, and I tested both fuses with a multimeter. Looks like the box was very slightly heated as well. Fortunately, its only localized to the high beam fuse. I removed the fuse anyway just to be safe. Odd, the headlights function normally, no sign of any problems. I just happened to notice the fuse by accident. I guess I will take it in to be looked at, electronic diagnosis is not my strong suit. Any ideas?

[Ryan King]

I decided to clean my fuses today. I noticed the high beam fuse had been hot to the point of melting sometime in the past. I turned my lamps on and checked. The fuse will become hot pretty quickly. The low beam fuse is fine, and I tested both fuses with a multimeter. Looks like the box was very slightly heated as well. Fortunately, its only localized to the high beam fuse. I removed the fuse anyway just to be safe. Odd, the headlights function normally, no sign of any problems. I just happened to notice the fuse by accident. I guess I will take it in to be looked at, electronic diagnosis is not my strong suit. Any ideas?

I don't know if this counts for anything, but I did reroute my Fuel Pump fuse outside the fuse box by soldering in an inline fuse too since it tends to get quite hot. I don't know about the high beams... are you sure you have the correct amp fuse in there?

[Michael]

Fuse size is correct, but even if it was too big, something would be causing it to get too hot. I did replace the fuse with a new one of course before doing anything.

[WelmoedJ]

Usually this points to bad connections.
Those bad connections can be anything from corroded connectors to bad ground.
Corrosion causes resistance and so raise the temperature in wiring resulting in burnt plastic (fusebox) or even in fire.

Therefore check and clean the fuse's pins and fusebox connectors, wire plugs and also all ground connections to the frame (at least the ones front left and right near the horns).
Also check the socket of your head light switch (you may want to change the stock situation where the current runs through the switch into the switch only activating a relay that switches the current to the head lamps, if not yet done).
Ref: Toby Peterson's K3003DP (Headlight switch bypass kit).

[Bitsyncmaster]

Way back when this was a HOT topic, I did some testing of using the recommended 20 amp fuse for the headlights. Any fuse will get hot if running close to the "blow" current. That is how a fuse works by melting a metal conductor. The fuse seemed to run cool up to 15 amps and the stock headlights would run less than 15 amps. But a lot of us are using higher power headlights but the siverstars still keep the fuse cool. It was the guys over the pond that were running higher power bulbs and were seeing headlight fuses melting. They could not get sealed beams and were using the newer type bulbs.

The fuel pump runs about 7 or 8 amps and the WUR heater and one relay add about 1 more amp. I have seen the WUR heater short circuit burn the wires in the WUR and still not blow the fuse but that would definitely get the fuse hot.

But corrosion on the fuse and pins is mostly causing headlight and fuel pump fuse heating.

[Michael]

Well I do have the xneon upgrade, which is really just halogen bulbs. The fuse was indeed 20 amp. I very seldom run high beams, so it may have been like this for sometime, but I will clean the contacts and see where I stand. Thanks for the replies.