Wire getting to hot to touch

[k13evin]

Just did a 3g upgrade and was sorting some wires under the dash. When. I touched the red with green stripes wire it was very hot. Looks like it goes to the ignition switch but I could be wrong. Any one ever have this happen

 

[Rustytruck]

You best chase that wire out. Red with green come from the ignition switch and feeds several circuits. Something is drawing too much power. looking at the picture your buckling the insulation. That could start a fire.

 

[broncodriver99]

What year? Red w/green should only be feeding the ignition coil unless there is some emissions stuff involved. It does go to the ignition switch.

 

[broncodriver99]

I think Rustytruck is thinking of green w/ red. That is the heavier gauge wire that feeds multiple things.

 

[DirtDonk]

Yes and no. The Red w/green wire goes to one place only, and that's the ignition coil on pre-Duraspark setups, and maybe other parts of the ignition for Duraspark (don't remember that last bit for sure).
That means that under the dash it is a resistor wire and is expected to get very hot. So yes, that part is normal.
What is not normal is that it's not completely covered in heat and flame resistant braided outer jacket/sleeve. It's never part of the rest of the harness because it gets so hot.

The other strange thing would be if it's Red w/green all the way. Normally the jacketed part is a faded Pink looking stuff. Follow that wire and see where it goes and if it changes color and has a separate section that's connected with simple push/bullet connectors.
If it's Red w/green all the way to the firewall, then it's ok for it to be hot, but it should be covered to protect the rest of the wires.
If it's got a separate section between the connectors (so you can replace the resistor part when it goes bad) then the section you're showing near the key should NOT get hot. Means that there's just too much load on things, even for normal wire.
If that's the case, maybe you have other things using that circuit that should not be there.

Well worth digging into a little deeper.

Paul

 

[k13evin]

77 302. It goes to the ignition. Almost looks as it loops back in to it some how. But I could be wrong

 

[k13evin]

So here is the wire. Big red wire with green stripe goes to the ignition. Then you have that red wire and what looks like a gold stripe going out of the cab. If the coil was hooked up wrong would it cause this ?

 

[broncodriver99]

That e coil is definitely going to pull more current than a stock can coil.

 

[JAFO]

You better check your fuse. If you have a wire getting so hot it is melting the cover, your fuse to the wire is too big. You want to make sure the fuse matches the wire gauge and if you are blowing fuses, find the problem, don't increase the fuse size so no chance of fires.

 

[k13evin]

Nothing is melting as far as I can see. It's weird tho those other two wires coming out the black round thing are not warm at all. Only the red with green stripe going to the ignition switch.

 

[DirtDonk]

Looks as if there have been a fair share of modifications to the harness over the years. In addition to any additional current pulled by the coil (don't know if or how much that would be) any additional connections will also create heat if they're not done exactly right.

It would definitely normally loop around under the dash. It's extra long and extra small to build up resistance. That's what a resistor wire is. It's long and small.
This resistance is heat, so that wire is always going to be hot. Never seen one that was all Red w/green it's whole length, but the '77's were probably different from what I've worked on most of the time. Too bad i didn't save the '77 harness I took out of a buddy's rig when we re-wired it. Would have been nice to see the comparisons.

Paul

 

[Joe473]

I would expect that e-coil would not need a resistor, check and confirm and if so bypass the resistor wire. When I first got my truck that resistor wire almost took out the whole harness!!
If it is needed listen to paul and make it separate!

It was not separate and I had a starter relay go bad grounding the I terminal. As soon as I turned the key on it was a high resistance short from battery through ignition switch through resistor wire to grounded I terminal. Harness started smoking while I was trouble shooting bad starter relay. Thank go I wasn't going down the road.


Sent from my SM-G900V using Tapatalk

 

[k13evin]

It's really weird. The red with green stripe starts from the black thing and goes the the ignition switch. So can I just remove it. I find it odd the brown and red with gold stripe do not get hot at all. Nor do any of the wires coming off the coil. That funky wire is the only thing getting hot. So what would be the best thing for it?

 

[Steve83]

...those other two wires coming out the black round thing are not warm at all. Only the red with green stripe going to the ignition switch.

That means either there is some load going to each of the cool wires, or the one that's carrying all the load is thicker (lower gauge) than the hot section. ...and the black thing is a "splice". The wires are resistance-welded together, and then black rubber is molded over the weld. The "gold" wire is actually brown (Br 262) coming from the starter relay. Is anything spliced into that wire? Is it connected properly to the relay's "I" terminal? Look closely at the relay's case - it should have "S" and "I" molded into the plastic above the small terminals.

This shows standard wiring for a '77:



The resistor and the ignition feed are R/Gn 16; the splice (S-205) is in zone E7.

The can coil should have 0.8-1.6 Ohms primary resistance; the E-core 0.3-1.0, so it is lower, and would draw more current. But since the E-core was designed for 12V, it doesn't need resistance in circuit 16. I'd overlay a R or Gn wire from the ig.sw. past the splice to the cool R wire, which will eliminate the resistance and keep the wire cool.

But I'd also look for any other draws on circuit 16 between S-205 & the coil.

 

[DirtDonk]

It's weird tho those other two wires coming out the black round thing are not warm at all. Only the red with green stripe going to the ignition switch.

Nothing weird at all. As said previously, it's supposed to get hot.

So can I just remove it.

Sure, if you put something else in it's place from the ignition switch.

I find it odd the brown and red with gold stripe do not get hot at all. Nor do any of the wires coming off the coil.

What exactly do you find odd about that? Those are normal wires doing a normal job, so would, under normal circumstances, never get hot.

That funky wire is the only thing getting hot.

Going to harp on this for a bit longer because we've been discussing this since this morning. As we've explained, that funky wire is SUPPOSED TO GET HOT because it's a resistor wire and that's what resistor wires do. The resistance makes them hot, which builds more resistance, which builds more heat. On purpose.
That's why they're normally covered in heat barrier sleeving and kept away from the other wires.

This resistance lowers the voltage from 12v give or take, to 9v give or take. For the old ignition systems to last longer since they were basically 6v systems upgraded over the years until they finally got changed altogether.

So what would be the best thing for it?

Like Joe and Steve said, bypass it with regular wire (14ga is a good size) from the engine side of the splice to the ignition switch. This will eliminate not only the resistor wire but the Brown wire too, which is no longer needed.

With all the other obvious modifications to the wiring harness, any problems with a particular circuit's function and you'll have to follow each and every wire in the area you're working on to make sure it's connected properly and not deteriorating and not connected to something it's not supposed to be connected to.

Did your 3G install go well? Have it running yet to see if it's charging? Did you run a large wire or cable from the output directly to the battery or starter relay/solenoid?
This is because you can't continue to use the Black w/yellow wire that used to be on the old alternator.
Your Green w/red wire from the ignition switch would be used to energize the alternator. There should be a matching Green w/red wire coming out of the 3G connector if you have a stock connector.

Good luck.

Paul

 

[k13evin]

Ok I see now. Yeah the 3g install went well and is charging right too. I just never really seen that wire before and was redoing my tack so I pulled all that down. Where is a good place to get the heat barrier?

 

[DirtDonk]

Not sure, but the usual suspects probably have it. My local FLAPS actually used to carry it until just recently. You might try yours first.

I'm wondering about that Red wire too. Is it one of yours, or was it like that when you got the Bronco? Just wondering about that splice right there near the Green w/red wire. And you say it's got a stripe, but does it carry that stripe all the way?
I see a Red wire (maybe the same one?) coming out near the coil. Know where it runs to?

Back to the sleeve, does your Green w/red wire have a junction other than that permanently sealed splice? If not, I guess they got rid of that at some point. Maybe they wanted better reliability through fewer junctions and connectors.
Bottom line though is that instead of going to the hassle of trying to cover it, just bypass it to get full power to the ignition. That would give you your best performance.
The only downside I can think of is that you would not be able to use a stock coil after that. But considering the upgraded coil you're using, that would not be much of a downside. Keep the modern coil and dump the resistor wire.

Paul