Headlights keep blowing fuses

[his15153]

So my headlights seem to keep blowing the fuse. After the fuse blows, I have to switch to the high beams, which don't seem to blow any fuses. I changed the headlight switch, thinking that it might be the cause. I have driven the truck once at night since then, and the headlights worked for about 10-15 minutes, before it blew the fuse. Now, when I put the high beams on, all the lights flicker on and off. If I turn the lights off for a few seconds, they will stay on for a minute and flicker again.

[cdowns]

you have poor grounds causing all your problems

[his15153]

The wiring looks fine. I don't see anything that looks out of the ordinary in terms of the wiring. Except for one wire. There is one black wire coming into the cab that is in the bundle with the other headlight wires that seems to have had the shielding melted off of a bit of it. Also, it is not hooked to anything. I tried grounding it, but nothing happened. The light still flicker. I have also noticed that you get a bit of a flicker in the gauges as well when it happens.

[cdowns]

giving those wires a stern look and pondering the state of the universe accomplishes nothing

plug back of light bulb trace wires take wires apart clean wire contacts to bright metal to metal contact // that is the old school way of gettin lights ta work

[SS Tim]

Since the truck does not have a headlight fuse it sounds like there are issues. The factory headlamp switch has a built in circuit breaker for protection. First thing I would suggest is looking at a manual and running the wires down.
The factory manuals can be downloaded here with some wiring diagrams in the service manual unde body electrical.
http://67-72chevytrucks.com/vboard/s...d.php?t=558016

[Wrenchbender Ret]

These trucks don't come with fuses on the headlights. What amp fuse are you putting in? Put a voltmeter on the battery & see what the regulater is doing. If the voltage jumps around that is what your flickering is caused from.

[heyjoe]

Another thing to check is the floor mounted hi-beam switch and its connector.

[pritch]

Which fuse is blowing?

[his15153]

The fuse that keeps blowing is the fuse on the front side of the fuse block (on the other side of where the wires attach). I've uploaded a picture of the fuse block, it is the missing fuse that is the one that keeps blowing.

Also, I have pictured the one wire that has the shielding melted off.

Also, when I put the old headlight switch back in, the lights stopped flickering. The fuse still blows though. So I don't know if the flickering with the new switch is because it was defective, or there is another problem.

[heyjoe]

What the heck kind of truck is this? What year they started putting in that type of fuses?

[SS Tim]

If that is a 67-72 truck then it has some sort of replacement wire harness/fuseblock. With melted wiring and apparent shorts I'm going to have to tell you to get help locally if you are not familiar with auto electrical systems. To be on the safe side I would also suggest pulling the negative battery cable too. This is not going to get better by itself.

[heyjoe]

Originally Posted by SS Tim

If that is a 67-72 truck then it has some sort of replacement wire harness/fuseblock. With melted wiring and apparent shorts I'm going to have to tell you to get help locally if you are not familiar with auto electrical systems. To be on the safe side I would also suggest pulling the negative battery cable too. This is not going to get better by itself.

x2
That's what I was kinda thinking.

[Special-Ed]

its time to hire a pro!

[Bigdav160]

It would help to have a little better picture of how the fuse block is wired in. The color wire that connects to the fuse would help determine what part of the circuit your problem is in.

Fuses blow because of the lack of designed resistance in the circuit. The source of resistance in your case is the headlamp bulbs. What kind of headlamps does your truck have?

If it was my truck and I didn't have any electrical tools I'd start with disconnecting the head lamp bulbs. Turn on the lights, flicker the dimmer switch, grab the harness with my hands and move them around. If the fuse still blows disconnect the dimmer switch and do the same thing. the problem is a chafe in the harness to metal.

If the fuse doesn't blow with the headlamp switch "on" then there is something wrong with your headlamp bulbs. Plug them in one-at-a time and do the above testing.