Fuse box fuse melting issues

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Jun 24, 2003
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Recently replaced wiring harness with the coolerman s harness

Wiring harness. Question. having trouble with the fuses melting getting too hot. Mostly just the one for the lights the first location. The fuse melts and solder drips out of it. What could be causing this problem.
WHat is the cause of excessive heat at the fuse panel terminals?

voltage regulator?
 
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I'm not the best when it comes to electronics but to much load on the circuit would be my guess. Not a spike in current which would blow the fuse without melting it, more like load right at or near the max causing things to overheat. You might also try switching the brand of fuses you are using to see if they might be the weak link.
 

S.CarolinaFZJ80

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I.e. Higher wattage headlights such as, the Koito H4 upgrade kit need to be run on a sub-harness wired direct to the battery using only the stock wiring to trigger the Lo/Hi relays.

If one installed headlights like these without an beefed up sub harness, one might experience this.
 

Engineer8000

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What condition is your fuse panel in? The headlights have a large current draw and bad connections heat up fast. If the fuse is made hotter it will open sooner. Definitely make sure you are not running higher wattage bulbs. My fuse panel is not that great and that fuse always gave me trouble. I installed the H4 upgrade and it is much better.
 
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What is the H4 upgrade ? The fuse panel was brand new along with the wiring harness. Not sure about the head lights. If they have been upgraded or not. The volt meter read 14.8v.

What fuses do you all use? I bought the cheap Bussmann from the parts store. Is there a stronger one available?

Thanks everyone.
 
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H4 is a better, more wattage bulb. The wiring in these older vehicles creates issues that can draw more current. The best remedy is to wire the vehicle so the headlamp switch only controls the relays that are big enough to handle the current needed for the bulbs. Originally the switch would be in the circuit with the bulbs and all current went through the switch and wiring. Take a look .
H4 wiring.JPG
 

Dizzy

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The volt meter read 14.8v.
Kinda high. How much voltage with the engine off?

How fast does the fuse blow? Immediately, or over a while? What is the amperage of the fuse installed? Will you burn out a fuse if you have only one headlight connected?
 

Dizzy

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With the battery negative disconnected, is there any conductivity between the low-beam and high-beam at the headlight receptical? How about when the dimmer switch is in the other position? (I wonder if you are actually trying to run both high and low beams at once)
 
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My short answer the temper in the clips for the fuses has over heated from a loose connection right in that area. If everything in the area is in good shape only the fuse should blow. Problem with loose connection is it generates heat the more it heats the worse gets the more heat it generates. If there is no spring left in the metal the holds the fuses don't be fooled the fuse block is done. Delt with this a lot in HVAC fused disconnects.
 

Engineer8000

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This is why I would not flat tow my 40 behind my truck/camper, I feel safer with the rig on a flatbed trailer behind everything. Something that has brakes, something that will stop itself if it breaks away, something that I don't have to worry about smoking any 40 parts.



Even if I probably exceeded the tongue weight of the Super Hitch.

What is the H4 upgrade ? The fuse panel was brand new along with the wiring harness. Not sure about the head lights. If they have been upgraded or not. The volt meter read 14.8v.

What fuses do you all use? I bought the cheap Bussmann from the parts store. Is there a stronger one available?

Thanks everyone.

81110-60P70 H4 upgrade kit from Toyota
 

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