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GinaParmesan 01-22-2018 03:16 PM

Melting/burning ignition fuse
 
Iíve been parked awhile.Yesterday I noticed the plastic on the ignition fuse in the front cab was melted. Not sure when that happened. So I replaced the fuse. I think itís a 20A. She started and ran fine this morning, but on todayís drive I smelled a stink and yep, that same fuse was melting again. What could be causing this?

The only things electrical Iíve done lately were (1) putting in new regular turn signal, stop etc. bulbs (2) LED headlights (3) LED side-light bulbs.

bkahler 01-22-2018 03:51 PM

Quote:

Originally Posted by GinaParmesan (Post 2058438)
Iíve been parked awhile.Yesterday I noticed the plastic on the ignition fuse in the front cab was melted. Not sure when that happened. So I replaced the fuse. I think itís a 20A. She started and ran fine this morning, but on todayís drive I smelled a stink and yep, that same fuse was melting again. What could be causing this?

The only things electrical Iíve done lately were (1) putting in new regular turn signal, stop etc. bulbs (2) LED headlights (3) LED side-light bulbs.

If your coach has the Air Ride suspension in the rear then it's possible the fuse is for the air compressor for the rear suspension.

I'm not familiar with the later coaches and how the air compressors were installed and wired but that's the first thing I'd be looking at.

Brad

Boom Sounds 01-22-2018 03:57 PM

Strange. I assume itís rated at 20amps. Youíre obviously drawing too much current through that circuit. If itís always been OK, then it suggests a short which seems improbable. It would be worth checking what runs through that circuit and isolating them, measure current as you try and find the cause eg stereo/steps/fridge control etc. Itís also conceivable that your blue finned isolator (likely make surepower) has crapped out. There are some good tests in the site or poss in the manual where you can test if it is working correctly. If faulty, you might join the circuits. I think (Brad can probably confirm this) that the isolator solenoid on the rear of the battery tray can also give rise to issues, but canít remember 100% on that. Good luck.

mayco 01-23-2018 02:08 PM

One would think that the fuse would blow and interrupt current before the actual plastic would melt.......??? I would second the previous posts starting with checking your compressor. It can draw quite a few amps through the ign circuit. Then you'll need to find and isolate all devices on that ign circuit. You might get lucky and find it right off. If indeed it's melting the plastic I would get right to it if you're using the coach. That's quite a bit of heat being generated and may be generating heat down the circuit somewhere.

Did I read your post correctly that it melted while the coach was parked and key turned off??

rmkrum 01-23-2018 03:17 PM

Another possibility...

Are the fuse holder contacts clean and tight? Sometimes the female connectors in the fuse holder can get corroded or dirty, loosen up, or otherwise make a bad connection...

If the fuse is not making solid contact, the prongs can slowly heat up and melt the plastic even if there is no excess current in the circuit...

Something to look into. The fuse and fuse holder contact should be clean, tight, and bright. If the fuse is too easy to insert, that's a place to go looking for issues with the connections...

bobmiller1 01-23-2018 05:10 PM

OK, I'll add my 2 cents for what it's worth....if you didn't have the problem before you changed the directional switch, I would look under the dash at the work you previously have done.....might just find your problem before you let to much smoke out. Regards, Bob

vswingfield 01-23-2018 05:45 PM

Quote:

Originally Posted by rmkrum (Post 2058771)
Another possibility...

Are the fuse holder contacts clean and tight? Sometimes the female connectors in the fuse holder can get corroded or dirty, loosen up, or otherwise make a bad connection...

If the fuse is not making solid contact, the prongs can slowly heat up and melt the plastic even if there is no excess current in the circuit...

Something to look into. The fuse and fuse holder contact should be clean, tight, and bright. If the fuse is too easy to insert, that's a place to go looking for issues with the connections...

I've had this problem more than once.

On more than one vehicle.

It can be very frustrating. As suggested, get all the connections shiny clean. Best of luck. :)

GinaParmesan 01-23-2018 07:42 PM

It was the LED headlights. The diagram for the H4 adapter harness was confusing, and thus I didn’t install them properly. A lead tester made it obvious the grounding wire wasn’t grounded. I guarantee that wouldn’t be a mistake any of you would’ve made. Probably too obvious. ;)

Anyway, lesson learned.

Thanks everyone for your input!!

ROBERTSUNRUS 01-23-2018 10:41 PM

:) Hi, as a previous automotive electrician, fuses melt from bad connections. Overloads blow fuses.

bkahler 01-24-2018 04:44 AM

Quote:

Originally Posted by ROBERTSUNRUS (Post 2058917)
:) Hi, as a previous automotive electrician, fuses melt from bad connections. Overloads blow fuses.

Great tip! I never really thought about it that way but it makes sense.

Thanks!

mayco 01-24-2018 07:22 AM

Quote:

Originally Posted by GinaParmesan (Post 2058872)
It was the LED headlights. The diagram for the H4 adapter harness was confusing, and thus I didnít install them properly. A lead tester made it obvious the grounding wire wasnít grounded. I guarantee that wouldnít be a mistake any of you wouldíve made. Probably too obvious. ;)

Anyway, lesson learned.

Thanks everyone for your input!!

I had to look at that H4 connector diagram several times to get it straight in my head when installing my LED headlights. The diagram pictures the connector facing you, when installed, you have to look at the diagram in reverse. It flips the ground to the other side of the connector when you turn the diagram around to install. A little tricky.

bobmiller1 01-24-2018 03:56 PM

Enough said.....always check what you have recently done if you encounter a new problem that you did not have before......Regards, Bob


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