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Unread 12-24-2008, 03:01 PM   #1
markmyst
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burning wires at starter relay

Today i go out and start up the jeep like everyday to warm up a little. I come back inside after shes idling good, after about 3 or 4 minutes i hear it shut down. All at once, no sputter no hack... just like i turned the key off. I go back out and hit the key, nothing at all. The key buzzer sounds and the headlights turn on but thats it. no blower motor no dash lights no nothing accept that stupid buzzer and lights. So i start poking around under the hood to see if i can find a indication of the problem. I find a burnt wire at the starter relay, the insulation was split off for 3 inches and the wire had broken from the heat. So just to check out if that was the problem i twisted the wires together and had someone try to fire it up. Vroom Vroom. right away she started and runs fine, all the bells and whistles are working again, for an instant.... Then i see that same wire start to heat up and burn again... like glowing red, melting off the insulation.
This burn started about 4 inches before the wire goes to the starter relay, and continues to burn twards the relay. The wire is green and it goes from the relay, (as a green wire) comes to a joint(looks like a rubber cylnder connection) at the wiring harness on the firewall, then comes out that joint as a red wire and goes into the harness. The connection the burnt one makes to the relay is the only one connected to the lug that is a 'pigtail'. Meaning there is one connection made to the relay, but 2 wires coming from that connection. all the other wires to the lug have a independent connection to it.

So what i am wondering is what this wire goes to. As i said its the only connection to the lug that has 2 wires coming from 1 connection (tied together before contact) so hopefully someone will know what the 2 tied together go to, and then i will have a 50/50.

Also i am wondering if the starter relay is what is causing this problem, at first i was just settled on bad wire, but then i read a post made by jeephammer and in it it says that the starter relay is what keeps the high amperage from going into the wiring harness/fuseblock/ignition that is suppose to go to the starter.. or at least that is what i gained from it. So using that lodgic, i thought that maybe the relay stuck in a position after starting the jeep that caused the high amps to go into that wire, inturn melting it down.

I really hope that someone can give me a little insight on this one. As i am scared to replace that relay, and replace the wire, making them the strong point and then the melt down happen somewhere not so easy to work.

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Unread 12-24-2008, 03:40 PM   #2
Gonewhln
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I would start with replacing the relay wit a BOSCH they are the best
They are rare to go bad but it's almost 20 yrs old check the ampage on the relay and replace it with the same.

If you want some relays cheap try a junk yard Nissan cars have about 20 under their hoods look for the early 90's or late 80's nissans
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Unread 12-24-2008, 03:44 PM   #3
ghost183
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snip that wire about 10 inches away from the burn, (wire needs to be replaced anyway) strip the insulation off, how is it? is it a...

nice copper color? normal,

black? indicating moisture,

brown? indicating excessive amp draw
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Unread 12-24-2008, 05:58 PM   #4
markmyst
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weather just wasnt permitting me going and working on it today, but i am just baffled at how to find out what these wires go to... other than ripping them out and seeing where they lead... So does anyone know what all should be connected to that lug in the middle of the starter relay? And the 3 pin and single pin connectors? been looking at wiring diagrams so long that i can see lines everywhere i look. Please help with this. In reply to the just replacing the relay, i thought about that first... but if i can fire it up, is the relay bad? like i said, it will start.. and run, untill it burns that wire to who knows where and then it dies IMMEDIATLY! I am just lost... Is there a way to see if the relay is burning the wire or whatever else the wire connects to is burning it? As i said i hadnt had any problems untill today, and it instantly burns completely through the wire, i mean in about a second! And this morning it ran fine for a good 3 or 4 minutes so what ever it is, was a failure after running for a couple mins. not something that happened over nite while it was sitting.... by my lodgic anyways.
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Unread 12-24-2008, 06:35 PM   #5
sentinal02
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those wires are actually your "fuse box". the early model YJ's used fusible links off the starter relay lug to distribute power to the rest of the jeep. they're designed to blow just like fuses in the event of a short. you've got a short further down the line on the circuit that that link is feeding. and you really need to stop putting just a standard wire back in there in place of the link. it's like putting a 50 amp fuse into the holder after the 20 amp kept blowing. you're just going to start burning more wires where ever that short is.
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Unread 12-25-2008, 11:44 AM   #6
markmyst
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i dont replace fusable links with regular wire. Today was the first chance i had to climb up under the hood and see what i was really doing. And yes it is a burnt fusable link. its one of the only 2 links that are connected together before terminated on the relay. can anyone give me an idea of where to start looking for the short? and is there a chance that maybe the link just became weak and burnt? or does a burnt link always spell disaster? I know that ive had regular fuses just go out, replace them and no problems. I just really dont know where to start looking for a short since there hasnt been any thing done to it at all... I would really like to not have to rip out the whole harness just to track down this one wire. surely someone out there knows where these 2 fuselinks, that use the same connector to the relay, run to... They are the only 2 that share a connector, and on one of them it is labeled B1 that helps anyone. i am currently looking at diffrent diagrams to see if that is maybe a label. It definatlly is the factory harness and links/connectors in this area (which is why i thought maybe it just went bad and nothing else was wrong, she is 19 years old almost!) and to answer the question about the wire stripped back.... clean as can be!
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Unread 12-25-2008, 03:22 PM   #7
sentinal02
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about the only clue you have to go on as to where the short is is what else isn't powered now that the link is blown. unfortunately it sounds like it's the one that powers the ign switch, which in turns powers most of the under dash fuse box. what i would try is pulling all fuses out of the box, replace the link and then put them in one by one to see which one blows it again. once you find that fuse, you can look up what the fuse powers and see about tracing it from there. if the link still blows with all the fuses removed, then you know it's before the fuse box.
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92 YJ 4.0L Ax-15 231
5" springs, 1" shackle 31's or 35's depending on my mood
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Unread 12-26-2008, 12:44 PM   #8
markmyst
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okay, that sounds like a good idea. the only thing that i dont know about is if i have all the fuses pulled will she still start up? As i said before the only time that the fuse burns is when she is running. If this is an issue, are there any hidden circuts that arnt listed on the fuse box that would cause it not to start if its removed? And if it was past the fuse box is it possible for the fusible link to burn out before the fuse in the box pops?
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Unread 12-26-2008, 10:26 PM   #9
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Quote:
Originally Posted by markmyst View Post
okay, that sounds like a good idea. the only thing that i dont know about is if i have all the fuses pulled will she still start up? As i said before the only time that the fuse burns is when she is running. If this is an issue, are there any hidden circuts that arnt listed on the fuse box that would cause it not to start if its removed? And if it was past the fuse box is it possible for the fusible link to burn out before the fuse in the box pops?
is it the jeep running or the fact that the key is turned on that's causing the wire to burn? there isn't a whole lot different between engine on or engine off as far as wiring goes, especially on the 4.2.
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Unread 12-26-2008, 11:16 PM   #10
Castr8r
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It is a fusible link, and you have a dead short to ground. Mine was in the power feed to the O2 sensor where it had rubbed on the intake manifold long enough to finally wear thru. I used up too many links trying to find the short, so I put a 30amp slow blow fuse in its place. I would suggest that you replace the link, then have somebody start it while you and a buddy watch under the hood after dark. Mine was found by accident late one evening by seeing the sparks on the manifold. Patience is a virtue that you may need/learn before you find the short! Good luck!
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Unread 12-27-2008, 02:09 PM   #11
markmyst
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i went through the best that i could and fixed/taped/dielectriced all of the wires and connections that i could get to.. .No help.
Pulled all the fuses. still starts and runs, but still burns that link.
To answer the question, It only burns the link when it is running. With the ignition on run and NOT started its fine. After about a second of it running it starts to burn.
I do know that its not the link that connects the alternator. Ive already tried pulling out all of the fuses and seeing if that corrects it with no help. I did not remove the flashers tho, thats going to be one of the next steps. I am still looking for a bulkhead diagram so that i can identify each pin on the bulkhead connector, figure out which one is dead that should be a constant and then map it out to where the problem may lie. If theres more insight from the additional information and questions it will be greatly appreciated. This forum help is the only thing keeping me from pulling my hair out!
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Unread 12-27-2008, 08:13 PM   #12
laybackman
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Quote:
Originally Posted by markmyst View Post
Today i go out and start up the jeep like everyday to warm up a little. I come back inside after shes idling good, after about 3 or 4 minutes i hear it shut down. All at once, no sputter no hack... just like i turned the key off. I go back out and hit the key, nothing at all. The key buzzer sounds and the headlights turn on but thats it. no blower motor no dash lights no nothing accept that stupid buzzer and lights. So i start poking around under the hood to see if i can find a indication of the problem. I find a burnt wire at the starter relay, the insulation was split off for 3 inches and the wire had broken from the heat. So just to check out if that was the problem i twisted the wires together and had someone try to fire it up. Vroom Vroom. right away she started and runs fine, all the bells and whistles are working again, for an instant.... Then i see that same wire start to heat up and burn again... like glowing red, melting off the insulation.
This burn started about 4 inches before the wire goes to the starter relay, and continues to burn twards the relay. The wire is green and it goes from the relay, (as a green wire) comes to a joint(looks like a rubber cylnder connection) at the wiring harness on the firewall, then comes out that joint as a red wire and goes into the harness. The connection the burnt one makes to the relay is the only one connected to the lug that is a 'pigtail'. Meaning there is one connection made to the relay, but 2 wires coming from that connection. all the other wires to the lug have a independent connection to it.

So what i am wondering is what this wire goes to. As i said its the only connection to the lug that has 2 wires coming from 1 connection (tied together before contact) so hopefully someone will know what the 2 tied together go to, and then i will have a 50/50.

Also i am wondering if the starter relay is what is causing this problem, at first i was just settled on bad wire, but then i read a post made by jeephammer and in it it says that the starter relay is what keeps the high amperage from going into the wiring harness/fuseblock/ignition that is suppose to go to the starter.. or at least that is what i gained from it. So using that lodgic, i thought that maybe the relay stuck in a position after starting the jeep that caused the high amps to go into that wire, inturn melting it down.

I really hope that someone can give me a little insight on this one. As i am scared to replace that relay, and replace the wire, making them the strong point and then the melt down happen somewhere not so easy to work.
I read your PM. A fusible link is a heavier gauge wire placed in a wiring circuit to act as a fuse (cheaper for the manufacturer). If it burns then you have a short in that circuit. You must find out where that short is.

Most important: You need to identify what circuit that wire is in.

The starter relay is a heavy duty switch that prevents voltage from reaching the starter until you close the relay circuit to allow that to happen. That is done via the ignition turned to the START position. After the engine is started, letting go of the key turns off the power to the starter relay preventing voltage to continue to turn the starter over. The starter solenoid not having any voltage, can't hold the starter drive out and it retracts back and the starter lives to start another day. I think your short is in the ignition circuit not the starter circuit since the wire burns after the engine is started. BUT I could be wrong.
I'll see what I can find on any wiring diagram I may have and post back ASAP

Chase out the wire that is pigtailed off of the burnt one. You may find you short there.
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Unread 12-27-2008, 08:26 PM   #13
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Does this help you. It is from an '88 but may be the same wiring design:

http://home.comcast.net/~laybackman/Untitled1.pdf
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Unread 01-24-2009, 10:13 PM   #14
markmyst
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okay after all this, numerous diagrams, so much information i had to sit down to process it all. After all the headache all the wire tracing, it all came down to she wanted some love! After taking the entire dash and steering coulmn out and various other things, cleaning all the connections and using dielectric grease (for further prevention) and having to put it all back together because my garage slot was in need by the owner... Volla... She is alive. I dont know what fixed it... but it is fixed with nothing more purchased then some dielectric grease and a bunch of asprin
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Unread 04-03-2010, 09:39 AM   #15
jschulz85
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wires

Th exact thing happend to mee there are 2 green wires with fusible lnks and one of them burned the exact same as yours. Please tell me if you figure this out im am pulling my hair out, Thank you
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