Fuse Link Box Repair ~ MB434379

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sealica
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Fuse Link Box Repair ~ MB434379

Postby sealica » Sat Jun 09, 2018 7:33 pm

Hello!

My van blew a fusible link (the one marked "LIGHT" in the photo below) the other morning after putting on my hazards, and shutting the engine off. The fog lights may have also been on. After walking away from the van (unloading a canoe) .. I noticed my hazards didn't work, but didn't inspect until after unloading the canoe. Upon closer inspection the stereo, clock, hazards, headlights, fog lights, and little red lights in the door no longer functioned. Turn signals totally OK.

Replacing the fusible link was made impossible (or seemingly) by the spade connector of the fusible link melting/damaging/getting stuck on the male terminal within the fuse box.
fusible link housing.jpg
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I looked into replacement parts, and the fuse box looks like MB434379 and was about $105 CAD via Amayama shipped in 17 days or so. 830701B in picture.
fuse box etc.png
fuse box etc.png (146.79 KiB) Viewed 155 times


I wanted a quicker fix (because no lights at dark is quite serious!) so I went with a used fuse box from Rocky Mountain $56. The used part came with wires cut which was unnecessary. At the time I hadn't completely removed the fuse box since I still wanted to be able to drive to assemble the parts for the repair, Etc. So I thought they must know something I didn't and the fuse box couldn't simply be unplugged.
fix.jpg
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After removing the fuse box I'm like "What? why not just unplug the connectors and sell the part without cut wires??". White one was a little difficult to remove yes ... but I'm definitely an amateur mechanic / electrickery tech.

Is it fair to expect a business selling parts to know this kind of thing? The hassle of attempting to return the part or whatever was not worth it although I wonder if I would be better of had I just immediately ordered the part from Japan instead of fooling around to save $50.
crimp.jpg
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Are crimp connectors splicing two pieces of wire as reliable as the OEM connector? I don't want to fool around with being stuck on a logging road a hundred kliks from civilization having to re-splice a wire? I'm thankful Rocky Mountain got my lights back in action quick, but I feel the ideal repair would be to simply plug a new fuse box in. But at this point it may not matter if crimps are genuinely reliable which may be where Rocky Mountain is coming from ...

OR that may be made redundant by another issue. With the fuse box unplugged I noticed that perhaps more serious than my concerns about crimped wire, I found damaged insulation of one of the wires going into the back connector .
connect_harness (2).jpg
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So I did a quick fix by wrapping a bit of tape around the damaged insulation hoping the wire fray isn't too bad. But I think I should probably do something like crimp/solder a new connector here (very short on wire ...) or perhaps bypass the connector entirely, or use a new connector(s). I think it's unlikely a new connector can be had, but I think it's effectively just two spade terminals with a plastic box to insulate / make removal easier. Any chance torn insulation on the wire could be the root cause of the blown fusible link in the first place?
connect_fix.jpg
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Appreciate any tips any might have!

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Growlerbearnz
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Fuse Link Box Repair ~ MB434379

Postby Growlerbearnz » Sun Jun 10, 2018 12:37 am

The chopped off wires just make me sad. It's difficult enough to keep the damned things plugged in, how could they not notice that it just unplugs?

I like your theory about the exposed wire being the cause of the failure. On those connectors you can put a tiny screwdriver down beside the spade terminal, depress the metal latch, and eject the spade terminal out the back of the plastic housing- from there you might be able to use some heatshrink to cover the nasty exposed wire?

*Julia Child voice* Here's one I repaired earlier:
repaired.JPG
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I'd also check all the other wires in the area for damage. The wiring harness loves to rub through where it passes from the battery box into the engine bay.
Nothing says "poor workmanship" more than wrinkles in the duct tape.

sealica
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Fuse Link Box Repair ~ MB434379

Postby sealica » Sun Jun 10, 2018 9:17 am

I'm considering ordering the new part from Japan, but I can't seem to find a way to confirm whether it would come with wires/plugs installed.

I don't see a way to remove the wires from the back of the fuse box ... perhaps there is? But the only pics online I can find of the replacement part (Russian sites) seem to show the fuse box just by itself; no wiring ...

I checked the other wires in the area and all good. The harness isn't rubbing on that area although I see how that could happen. I'll give the plastic housing a closer look for the latch you're talking.

But if that doesn't work ... would it make sense to just fit a new pair of spade terminals to the wire itself and bypass the housing on that one wire?

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Growlerbearnz
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Fuse Link Box Repair ~ MB434379

Postby Growlerbearnz » Sun Jun 10, 2018 3:13 pm

Here's how it works on a fusible link (I tried to demonstrate on the same connector you're working on, but my wiring is pretty tightly packed in the battery box and I didn't fancy removing the batteries.)

Look for the little rectangular hole that's beside the spade terminal you want to eject.
1Spade.JPG
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Use a small screwdriver to push the spade's metal tag down...
2Screwdriver.JPG
2Screwdriver.JPG (34.47 KiB) Viewed 132 times

...and the spade terminal will just slide out the back. You can see the little metal tag/latch clearly in this picture.
3ejected.JPG
3ejected.JPG (69.73 KiB) Viewed 132 times


Before reinstalling the spade, bend the little tag out a bit. When the spade goes back into the plastic housing you should hear the tag go "click" when it's in place.

sealica wrote:would it make sense to just fit a new pair of spade terminals to the wire itself and bypass the housing on that one wire?

It looks like the crimps you've used on the butchered wires are indeed proper all-metal crimps with slipped-on silicone sleeves. Perfect. Those should be quite reliable as long as they're rated for the size wires (they're big wires!) and they don't get bent near the connectors. I'm cheap, so on those butchered wires I would have used an inline pigtail-twist joint and soldered it.
twist.JPG
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Seeing as the wire on your damaged connector isn't frayed, only exposed, I would just insulate it (which will also protect it from further bending and fatigue) and call it done.
Nothing says "poor workmanship" more than wrinkles in the duct tape.

sealica
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Fuse Link Box Repair ~ MB434379

Postby sealica » Sun Jun 10, 2018 6:43 pm

Awesome that was really helpful. Although now I'm wondering if the spade terminals in the fuse box eject the same way? Tried on my old one without much success, but maybe just need a tinier screwdriver. I did use 10-12 gauge crimps, as I noticed the wire was larger than the normal 16-14 in the van ...

It was very difficult to remove the problem spade. The top one popped out easy after pressing the latch and pushing on the end of the spade with a larger screwdriver (flathead). But I think the lower one was stuck in there because of the heat generated (deforming plastic slightly) by the blown fuse. You can see the charred plastic in my pic. I was being careful, but I slightly bent the spade terminal when trying to get it out.

short_circuit_housing-1.jpg
short_circuit_housing-1.jpg (309.77 KiB) Viewed 123 times


I hit the exposed wire with a bit of deoxit to try and clean up the blue oxidization, but probably not the best use of deoxit? Will grab some larger heatshrinks tomorrow because mine are too small to fit over the spade. Not sure if the same is possible with the female side (coming from the fuse box) of the housing? Same deal with the charred plastic on this side; which is another vote for used parts with intact connectors?

short_circuit_spade-1.jpg
short_circuit_spade-1.jpg (406.78 KiB) Viewed 123 times

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Growlerbearnz
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Fuse Link Box Repair ~ MB434379

Postby Growlerbearnz » Sun Jun 10, 2018 7:31 pm

sealica wrote:...now I'm wondering if the spade terminals in the fuse box eject the same way?


They do, but for some reason they take a bit more effort (I tried on a spare fuse box I have). One of mine was more difficult to eject than the rest- it looks like it got hot and slightly melted too! A small allen/hex key makes a good eject tool too, if you're out of long, thin screwdrivers.

Hmm. That spade connector is nastier than I thought. Sometimes the overheating and corrosion will make the copper wires weak- just check that your wires aren't waiting to snap.

If the wire is brittle either add solder (which only works if you can deal with the loss of flexibility) or cut if off and fit new connectors.
Nothing says "poor workmanship" more than wrinkles in the duct tape.

sealica
Posts: 137
Joined: Mon Aug 08, 2016 5:38 pm
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Fuse Link Box Repair ~ MB434379

Postby sealica » Tue Jun 12, 2018 9:00 pm

The exposed wire leading to the spade doesn't seem brittle. I was pulling quite hard a few times in the process of removing the plastic housing and it didn't feel like it was waiting to snap. I backed off for fear of breaking it, but more being careful as it didn't feel like it was going to go.

Getting that particular style of terminal that would fit into the plastic housing doesn't seem likely except by ebay, or lots of local asking and back-and-forth.

For future reference if I was stuck somewhere needing to repair this and all I had was access to Canadian Tire type terminals ...
-would two ring terminals put together with a nut + bolt do the trick? At least temporarily?
-Or the pretty standard "quick disconnect" blade terminals. As long as I isolated each connection with tape / wiring loom?

I'd rather get this sorted tomorrow, but seems easier to do something now then after putting heat shrink on and reassembling everything. Solder sounds like the way to go, but I'm pretty new at soldering. If I do a rough cleaning of the corrosion should the solder do fine, or do I need to be really thorough to make sure the wire shines? I hit it with deoxit and that improved it slightly, but still pretty grungy just worried of being too abrasive (file) or adding lots of dust with sandpaper ...

Thanks!!


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