Headlight Fuse Melting

[Gradient]

Referenced thread:
http://www.steelsoldiers.com/showthread.php?124720-LMC-Truck-Head-light-circuit-mod


I really appreciate this thread and the other sticky, I just wish I would have read them earlier. My headlight fuse fried 92 miles from home, at night and I had to wait 2 hours for a tow (luckily my AAA 100 mile tow was still available).

Here is my problem, I tried a new fuse, and a paper clip jumper while I was waiting for the tow truck but no lights. The fuse block melted around the left terminal of the fuse and the left fuse tab broke off inside and melted on the connector. How do I fix this without having to buy a whole new harness? Do I just disconnect all the circuits on that fuse and run inline fuses for them?

 

[top_prop]

I've heard of horns failing and causing problems like this... So be careful that you've isolated what drew way to much current before you bridge the electric gap you now have in you fuse box.

I'd think once you've located the culprit you'd start by taking the fuse bock apart and see what is usable and what you're going to bypass. I'd pull a new lead from the 12v buss on the firewall near the gp solenoid into the cab a feed a small fuse bus you can get at any auto parts store and move each item over to its own fuse by snipping the bad/lost items off the back of the fuse block and but splicing and shrink wrapping them to to leads that are fed by the new fuse block (I don't believe you can find a new harness or fuse center for a cucv)

 

[Gradient]

I've heard of horns failing and causing problems like this... So be careful that you've isolated what drew way to much current before you bridge the electric gap you now have in you fuse box.

I'd think once you've located the culprit you'd start by taking the fuse bock apart and see what is usable and what you're going to bypass. I'd pull a new lead from the 12v buss on the firewall near the gp solenoid into the cab a feed a small fuse bus you can get at any auto parts store and move each item over to its own fuse by snipping the bad/lost items off the back of the fuse block and but splicing and shrink wrapping them to to leads that are fed by the new fuse block (I don't believe you can find a new harness or fuse center for a cucv)

Thank you, that sounds like a plan. I also just read a post where Doghead explains the possible culprits so I will start there.

 

[MarcusOReallyus]

Here is my problem, I tried a new fuse, and a paper clip jumper while I was waiting for the tow truck

Worst mistake you can make. If a fuse blows, it's for a reason - there's a short circuit somewhere downstream from it. If you jumper the fuse with something like a paper clip, you are just about guaranteeing some kind of damage to your vehicle's electrical system.

Sometimes it's significant damage, up to and including a fire that burns it to the ground.

NEVER jumper a blown fuse!

 

[Warthog]

I always like to use a .22LR

 

[MarcusOReallyus]

Yeah, that can add a bit of excitement to an otherwise boring day!

 

[the skull]

I always like to use a .22LR

Sounds like you have a blast troubleshooting electrical problems!

 

[Gradient]

Worst mistake you can make. If a fuse blows, it's for a reason - there's a short circuit somewhere downstream from it. If you jumper the fuse with something like a paper clip, you are just about guaranteeing some kind of damage to your vehicle's electrical system.

Sometimes it's significant damage, up to and including a fire that burns it to the ground.

NEVER jumper a blown fuse!

The fuse did not blow, it just got too hot and melted the plastic. I was only trying to jump it to see if the fuse box was still working, had not planned on leaving it in there.

 

[Warthog]

The headlight sticky helps explain why the box melts. So many other items run thru the headlight fuse.

 

[Gradient]

The headlight sticky helps explain why the box melts. So many other items run thru the headlight fuse.

Yeah, it was really helpful. I ordered the LMC truck harness last weekend and waiting for it to arrive. All the contacts in my fuse box were dirty and/or corroded from the previous owner- he must have ran the truck through a mud bog. There was mud under the dash, on the harness... EVERYWHERE.

 

[MarcusOReallyus]

The headlight sticky helps explain why the box melts. So many other items run thru the headlight fuse.

Yes, but some folks take it personally if you call that a poor design, so don't say that having completely unrelated circuits carrying half the electric usage of a small city running through one fuse marked, "HEADLIGHTS" is a poor design, and don't say that the headlight relay mod is a good way to alleviate some of the problems of that poor design which we aren't calling a poor design.

 

[max1008]

I will be doing this soon, will this help my dimming headlights when I hit the brakes and turn signals?

 

[cucvrus]

The design is fine if the fuse panel was not subjected to 30 years washing and mud and corrosion. And if you remove the fuse box and split it you can put a relay or a circuit breaker in place. You will need to add a fuse for the brake lamps also. That is on the same little buss bar in the fuse panel. Easy 45 minute job. Clean the headlamp ground at the radiator support and put a new ground washer on it. Always worked for me.

 

[Skinny]

It's all a poor design that becomes over stressed with age/corrosion. Pretty much all rigs up to the late 80's/early 90's have this issue because the current runs through the headlamp stalk. It's the nature of the beast. Why the rest of the circuits dim when you step on the brake or just over time is because a 1v drop due to corrosion will appear very noticeable in the headlamps, then it gets worse when you kick the brake lights on.

My suggestion would be to clean everything, make sure you charging voltage is 14v at idle with your foot on the brake (idle speed may need to be tweaked up a hair), add the relay kit so the headlamps get power straight off the battery, and maybe even add some LED lamps to lower power consumption on the lighting circuits. Only way to bandaid a flawed design that has 30 years of age on it.

 

[max1008]

Thank you, I have gone through all of the headligh/tail light connections and all are new or cleaned. Charging system is also top notch. I think that leaves me with the headlight harness mod, which I think will do the trick, I will let you know if this solves the problem. fyi- dimming headlights are even worse with m101a2 hooked up. Which makes sense because that also comes off the same fuse as headlights

 

[Red Dragon]

I had the same issue, I added solder to the tips of the 10A fuse. It effectively widened the tips enough to make a better contact. Have not had any issues since I did it a year ago.