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Fusible links

Discussion in 'The Garage' started by afroman006, Dec 6, 2005.

  1. afroman006

    afroman006 1/2 ton status

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    What could cause them to melt? I was wheelin awhile back and went to load up on the trailer and my truck would not even engage the starter. I later discovered that the fusible link up on the little junction block on the firewall is blown. Do I just replace it and see what happens or do I need to figure out why it blew? Thanks.
     
  2. ryan22re

    ryan22re 1/2 ton status

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    they melt from too much amperage. if i remember right, the junction block on the firewall gets its power straight from the starter. it should power the blower motor, the a/c compressor and i think has another wire running inside the cab (not sure where that one goes).

    so something caused the fusible link to melt...what that was, is the real question.

    by the way, i just got rid of all mine. see:

    http://coloradok5.com/forums/showthread.php?t=157475

    ryan
     
  3. unclematty

    unclematty 1/2 ton status

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    betterfigure it out first, it may keep happening!
     
  4. Yukon Jack

    Yukon Jack 1/2 ton status

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    Yep, start checking for a grounded wire somewhere. I put a new fusible link in my 69 once before finding out what burned up the existing fusible link. Turned the key, saw the fusible link going again but unfortunately, it didn't go quick enough and I got to watch the wiring harness from the alternator to the otherside of the firewall go up in smoke.
     
  5. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Had the same problem , never knew why . Fixed mine right next to a cove at the lake with some small wire on hand . Been like that ever since . Its just the same principle as a fusible link , a smaller wire that can burn up instead of the larger wire .

    I think mine was just an truck , in the desert heat .
     
  6. afroman006

    afroman006 1/2 ton status

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    Well I hae absolutely nothing heating or A/c related in my truck and all my accesories get their power dirrectly from the battery. Could cranking on the starter for extended periods of time cause it to melt? I've been doing that loat lately bleeding the fuel system in the truck (its a 6.2). I checked the link at the starter today, and it was intact but had melted the loom around it.
     
  7. Roz

    Roz 1/2 ton status

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    do u have a multi-meter? start checking ground resitance to the lead. if the links are in line with the power draw, the starter might have done it. but i would say more if that happened the connections on main feed wire are dirty.
    dont know to much about the 6.2 set up but electricity is like water, it finds the easiest path
     
  8. PonchoCatalina

    PonchoCatalina Registered Member

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    If you figure out what's causing that link to burn, I'd like to know. Yesterday I fired up my '86 Suburban (gasoline-powered) with the hood up and noticed smoke from the wiring at the firewall junction block (bulkhead connector). Upon closer inspection it turned out to be the short fusible section between the junction block and the intersection of two red wires. Oddly, it did not burn out, but just smoked the insulation. It still runs, but the now exposed wiring of the link glows red-hot, and only when the vehicle is running (I ran it only for a few seconds at a time to see what was going on - I wouldn't go out for a drive with my wiring smoldering!). Anyway, I haven't figured out the cause. Is it possible for the alternator go bad and produce too much amperage, as the problem occurs only when the engine is running? The only other thing worth noting is that I had taken the battery out and used it to crank an old Mustang, and the link smoked after I put the battery back in the 'Burban. Thanks for your thoughts.
    - Poncho
     
  9. afroman006

    afroman006 1/2 ton status

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    I replaced both links and the truck works fine now.
     

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