Ignition switch wire melting connector

[Frank68]

________________________________________
1968 Bronco with new Painless wiring.

Starts and runs well for a dozen + or so starts.
Next time I start it, the 70 amp painless maxifuse is blown.

So I jump the fuse and it starts and runs fine.
I shut it off and start it again just fine.
After I let it get hot, I shut it off and smoke starts rising from the back of the dash board and I hear crackling...turns out the yellow wire from the back of the ignition switch is REALLY hot and the connector melted to the blade terminal on the ignition switch.

I replaced battery terminals connectors and cleaned the terminals.
Replaced the voltage regulator (external)
Put a new 70amp maxifuse in and start it just fine.
Turn it off and try and restart but the 70amp fuse is blown again.

Why am I blowing this 70A maxifuse ?
and if I jump this fuse I run the risk of melting the ignition switch.

Do I have an ignition switch problem or something else?
Is there any way to test.?
HELP..


FRANK

 

[DirtDonk]

Hey Frank. Sorry to hear you're having a pretty dire issue with your new wiring. I sent you a PM and cc'd Eric at Painless on it too. Between the forum and Eric I think we should be able to at least narrow things down.

Even the fact that whatever the issue is effects the ignition switched wiring with too much load might be a clue.
I'm not sure myself just yet, but let me study the diagrams and think on it for awhile.

I know there are members here that have had "teething" problems with new harness installs, I don't remember any that blew the big fuse. But it's possible others have had the issue.
Obviously the switch connector melted because of whatever problem blew the fuse, was now being loaded on to weaker components because the fuse was bypassed. For the record, this is why you don't jumper fuses until you know you've dealt with the issue that caused the blowing in the first place. And even then, only when you run out of fuses and have to get home. And even then, you usually don't do that because you can melt other stuff farther upstream.
The fuse is there as protection obviously, and I know you did try a couple of fixes first. But obviously the issue was still there, and is something on the "switched" side of the harness.
I'm still trying to narrow down the possibilities, but knowing it goes through the switch is at least a clue.

Good luck! I think we'll narrow it down, but maybe some pics will help.
To post up pics here directly, you need to be a contributor for 12 bucks a year. Without that though, you can use an online hosting site and link the pictures here. Or in a pinch, you can e-mail them to me, or anyone with the yellow "contributor" beneath their name and we can load them to the thread for you.

Any of those options will work. Be good to see some areas of the install to check out.
Besides, we like pics of Bronco stuff here anyway!

Paul

 

[eric0o1]

Sounds like you have an alternator putting access amperage though the system. The techs here and myself have all experienced new alternator regulators being junk right out of the box. What's the output amperage rating of the alternator you are using? Do you happen to have a voltmeter installed? I'd be curious as to what the voltage is with the engine running in it's current state.

For starters I would replace the maxi fuse, disconnect the alternator regulator and disconnect the #915 wire from the alternator and insulate the ring terminal on the #915 so it doesn't short to ground. This will completely take the charging components out of the system. Put a battery charger on the battery and start your bronco and let it idle for a little while; even turn it off and start it a few times once it gets hot. Check the fuse after every key cycle. If the new fuse doesn't blow then I think it's be safe to say the alternator/regulator are needing to be addressed. Make sure the regulator and alternator are both properly grounded. Have the alternator tested and maybe replace the regulator again.

If the fuse still blows then we will go through the procedures of chasing down a short. Being that it's a battery supply fuse, a short would generally pop the fuse as soon as battery power is applied which is why I think you have issues with the charging system.

 

[DirtDonk]

Thanks Eric. I totally neglected to mention the "new parts are junk" scenario!
Thanks for the ugly reminder of what we get to deal with these days. Catches us pretty often with some of these parts.

A low battery and a high-output alternator could do this if he's using the basic charging system layout, yes?
But if it's a stock 45-60a alternator and the regulator is defective, it might put out 17v but not enough amperage to blow the fuse, correct?
Or are there variations on those themes?

Thanks

Paul

 

[eric0o1]

yes, a high output alternator could blow the maxi fuse.

As for 15v+ and not enough amperage to blow the fuse, I feel that would be hard to do. 45-60 a isn't a max rating of an alternator, just what its capable of sustaining at continuous duty.

For Example, I had to fix a 1970 International truck that had a faulty external GM regulator that was outputting almost 17v, 60 amp factory alt, but it melted the alternator output wire, bulkhead connector and burnt up the wires going into and out of the Ammeter and ignition switch.

 

[Frank68]

Thanks for the responses , but i think I need to tell you something before moving forward with suggestions because it may change your thoughts.

So I checked all connections to the ignition switch and everything checks out. I disconnected the small stereo power and I have no other accessories wired. I am doing this as a full resto-mod. gas tank to radiator and everything in between so as I was thinking about this all day, I recall that I have a Pertronix Ignitor 2 ignition and an MSD Blaster 2 coil. The instructions for the Pertronix ignition recommend removal of the ballast resistor, so I did. Now maybe the Pertonix Ignition and MSD coil are capable of handling the excess electrical but maybe the ignition switch is not? I just do not know.
Regardless I will take Eric's advice and run off the battery with the alternator charging system disconnected and see if I blow the maxi-fuse or not.

________________________________________
1968 Bronco 289, NV3550 with new Painless wiring.

 

[SteveL]

With the centech on my 66 a blade on the back of the ignition switch missed the female part on the harness causing the wire and plug to melt. It still made contact but the loose connection caused heat. When I contacted centech to get a new plug they said it's a common problem on the ignition switch and sent me the replacement parts free. Just one more thing to check

 

[DirtDonk]

The alternator putting out big power and a battery being a little too low could be the reason the fuse is blowing, but not as likely the reason the ignition switch wires are melting I'd bet.
Something at the other end of one of those wires needs to be pulling excessive current, or like Steve said, maybe there was excess resistance at the connector.

Did you say the smoke started after you turned off the switch though? If that's the case then maybe the switch itself is defective.
If it just happened that you noticed the smoke at the same time you turned things off, then it could still be somewhere else.
On the factory setup, the Green w/black accessory wire on the center post is a larger gauge than even the Yellow power wire. Not sure what gauge the Yellow wire is on the Painless setup. In this harness the main ACC feed off the center of the switch is a different color. Orange i think Eric?
But if the ACC wire is larger gauge than the 12v wire into the switch, and something in the switched accessories area could be shorted out (or intermittently shorting) and that could explain why the Yellow wire melted first.

What color is the wire that's connected to the side of the switch? Should be purple or pink if I remember. Anything else there would be suspect since that is a ground (proof out) during start.

Anyway, just rambling at this point. It's late (again!) and I'm trying to talk about something that Eric knows way more about.

Cant you post up any pics of the back of the ignition switch, or the offending melted connector?

Thanks

paul

 

[eric0o1]

The ignition switch can handle the new coil without any problems.

stereo power: how big of a wire is it and how/where do you have it connected? If you are running an amplifier if needs it own in line fuse at the battery and not tied into the chassis harness in any way except for the switch 12v turn on from the head unit to the amplifier.

Battery power into the ignition switch is a yellow wire, printed #934

 

[Frank68]

Maxi-Fuse blows when car is OFF

Things are going from bad to worse.
I was attempting to take Erics advice by disconnecting the alternator and running the car off battery.

So the first thing I did was try to replace the maxi-fuse and when I did it sparked and blew, literally with my fingers on it.
Since it was not running the alternator is not involved at all.
All 9 unused accessory wires and unused wires under the hood have heat shrink on the ends.
So it seems I have a short.
Where should I begin..

 

[DirtDonk]

What did you mess with just before this happened? Since this is now a new issue, or at least a worsening of a current issue, something that you bumped may have made the difference.

What about at the ignition switch? Have you been messing about and straightening wires? The Yellow wire is constant power, so might have some sort of fault along it, but I was thinking more of at the switch itself.

Hmm, speaking of the switch, could it have been in the RUN position when you were inserting the fuse?

Paul

 

[Frank68]

Just before this happened I replaced the instrument panel voltage regulator and made sure the proper ammeter wire was passing through the loop.

At this point maybe I should just replace the ignition switch?. I have a spare.

 

[DirtDonk]

Just a second more though. That ammeter wire is the big dog of the wiring harness on a Bronco. If something is amiss with that, it would blow the fuse in a heartbeat (or two!) and take no prisoners.

So double check that one. Look for anything it might be touching on the cluster, or anywhere else.
And you may know this already, but that wire as it goes through the cluster (either Red, or Black w/yellow?) is the very same wire that the Maxi-Fuse is connected to. And it's where every other wire ultimately get's it's power from.

It's also the same Black w/yellow wire that runs from the back of your alternator.
Like said, you may have known all that, and I think it's spelled out in the instructions. But it was worth bringing up again for the discussion.

Paul

 

[Frank68]

Good sign

So i replaced the ignition switch with the old one that was in the vehicle when I purchased it.

Since I do not have anymore good Painless 70A fuses, I put a hand held multi-meter across the painless maxi-fuse holder terminals and got zero amps across the terminals so I am not drawing current....

When I did this with the old ignition switch in the meter sparked and I did not attempt to get a reading.

I will put a painless 70A fuse in ASAP and let you know what happens.

 

[DirtDonk]

The meter may have it's own blown fuse now too. Maybe double-check to see that it still works for regular duties such as checking battery voltage.
The typical meter has a 10a maximum pass-through amperage capacity. Something that would have put down a 70a Maxi-Fuse would definitely take out your puny 10a fuse!

Or do you have one of those fancy ones with the high capacity?

Paul

 

[Frank68]

Progress

The old ignition switch worked, start/restart, turn on accessories, lights, blinkers, etc.

The other issue is that the old ignition switch does not return the key from the START position to ON so I will have to get a new switch and while I am at it a new lock cylinder

Bad news is the alternator is not charging the battery so I will have to replace it as well.

 

[DirtDonk]

If it was working before, don't replace the alternator until you test it. Way too many things can stop an alternator from charging.
Not the least of which is that fuse of course...%)
But Painless has a fuse I believe, that controls the Green w/red wire to the voltage regulator that would do it as well.
Connecting it incorrectly will do it, as will a fault with the Yellow sensing wire or a good ground.

However, yes an alternator can be bad. And it is nice to upgrade to a more powerful unit if you think you'll need it. But I'd hate to see you replace it only to find out the new one does not work either.
Easy to test on a running vehicle, and easy to have a local parts store test it before you get your new one.

On the lock cylinder, in case you did not know there are kits available that include the lock cylinder and two new door locks as well. This way you can keep the same key for both, just like before.

Good luck.

Paul