Ignition wires smoking in my '70

[70Mach351c]

Driving down the road this morning, all my lights all went dim, followed by a bunch of smoke from under the dash.
Pulled over and checked. the new wires for the temp. gauge I put in wasn't involved (had it out twice since then), so I went to head home....
The starter barely ran, it almost didn't fire, like a low battery, but it started fine five minutes ago. Then the smoke came again. This time, it was at the base of the steering column as it runs under the dash. big stream of grey-black stuff.

I will need guidance. It's obviously the ignition wiring. I have a '70 with a column-mounted keyswitch.
Questions:

• Where does the ignition wiring run? I guessing the switch or a relay is under the dash that I can look in on.
• Can the column be dropped down from it's mount onto the seat, or does it pull out telescope-style? If it's the former, I'll start there, if not I pull the dash.
• How much harness is involved? are there connectors at the firewall, or should I everything from the battery to the column?
• Last, please tell me I don't have to get a column, that the wires plug in somewhere.

 

[70Mach351c]

Found the problem

I took the steering wheel bracket off. I found the source of the smoke:

This is the 8-pin harness from the steering column. It's like a taco Bell commercial Crunchy, Melty hot and fried.
To the left is are the wires leading to the ignition switch. Among them is a big yellow wire, melted as the rest. They're actually melted on both sides of the plug, as is the plug itself. It looks like the little wire got it worse than the yellow at the plug.
I'm not sure which is the culprit.
Can I replace this section (keyswitch to plug, plug to ?) without splicing in wires?

 

[2+2GT]

The wires and plug are part of the switch. The hard part will be finding a good used 70 switch. This was a one-year-only item.

I found a clean one in a junkyard last year, got almost $100 on eBay. They often go twice that, now.

Many suppliers, including some big Mustang outfits, think the 70 was the same as the 71-73. No such luck. The housing assembly is mirror image, no way you can make it work.

Your under-dash harness is probably toast, too. I have fixed some, but it takes a whole day, even if it can be saved, and it must also be removed and re-installed.

IIRC, a repro 70 under-dash is about $800, for that you could get the "Painless", but you'd have to re-do the whole car. You might be able to locate a used 70 under-dash.

 

[tx65coupe]

I prefer the reproduction harnesses. They come pre-terminalized. The painless stuff you have to make your own connections.

So, The 70 switch is not available new from any of the Mustang parts places? That seems odd to me. I would think that they would not have any problem selling them.

 

[2+2GT]

I prefer the reproduction harnesses. They come pre-terminalized. The painless stuff you have to make your own connections.

So, The 70 switch is not available new from any of the Mustang parts places? That seems odd to me. I would think that they would not have any problem selling them.

They would have no trouble at all selling them, but no one makes the switch. The last supplier was Standard Products, and they dropped them 3-4 years ago. This means someone will have to make them, and even if they can find the existing tooling, you're looking at many thousands of dollars spent before one switch can be sold.

 

[70Mach351c]

Your under-dash harness is probably toast, too. I have fixed some, but it takes a whole day, even if it can be saved, and it must also be removed and re-installed.

IIRC, a repro 70 under-dash is about $800, for that you could get the "Painless", but you'd have to re-do the whole car. You might be able to locate a used 70 under-dash.

Wires on both sides are toast. there just isn't one of those black sleeves to melt around it. I haven't traced back very far, I'd get too depressed.

I also have seen prices for the underdash harness repro. However, it looks to be wired to actual connectors, where a Painless Wiring full-car has you re-use the same 40-year-old plugs, and you can see what shape they're in.

I'm leaning to a full re-wire. This wasn't the only electical issue, it is the one I'm unable to drive with. Anything more involved than a water gauge or radio I will defer to a pro. I do not screw with starter, headlight or battery circuits.

Thanks for the feedback.

 

[BarnStang]

You can use a 71 switch. I have done it twice. Cut the plug off the old one and splice it on to the 71 switch. Too easy. THe hard part is if you don't have a 70 switch to start with. If you stagger the splices, you can fit it all inside the plastic cover. (which I guess is now disintegrated...)

THe wiring isn't that hard. If the ign switch is the source of the problem-meaning its the direct cause of the short and not something else, get a new switch, and repair the wiring. THere is plenty of help here to get you through it.

 

[2+2GT]

That's right, I looked into converting 71 switches to 70, but it just wasn't feasable, there were too many problems reversing the housing. However, the wiring, although shorter, had the same plug. If the wires on yours are not damaged, by retracting the prong on the pin you can swap them into a new housing. If they are fried, you could splice them to the new wires in the plug.

 

[BarnStang]

OK, I got ahead of myself.
NAPAONLINE

You can order a new ignition switch for a 1970 mustang and it will be the correct switch-but it will have the wrong connector on it. Sorry for the confusion.

I actually got a defective one-the return spring was broken or too weak. Wouldn't return from the start position correctly. But, I had already spliced the 70 plug onto it. So, Napa wouldn't honor the return. I called the vendor and they were of cousre oblivious to this plug problem. So I mailed them the switch and emailed them pictures of the harness in the 70 under the dash. THey were amazed. But not enough to develop a one year only plug. THey sent my plug back to me, and called Napa and had them issue me a credit for a new one. Now I have a standing authorization for replacement 70 ign switches if I have already spliced them...and they are defective.

It was Echlin that was the vendor that I dealt with. Very helpful and sincere effort to resolve my problem.

 

[70Mach351c]

OK, I got ahead of myself.
NAPAONLINE

You can order a new ignition switch for a 1970 mustang and it will be the correct switch-but it will have the wrong connector on it. Sorry for the confusion.

Thanks for the link. I was scratching my head, as there is a difference between the switches themselves.

I finally got back to it pulled the cover and looked at the switch. Damn.
The ignition wire (the "on" position, keeps spark running, as opposed to the starter) is melted and bare, from the switch terminal to halfway through the engine compartment. I'll start removing tape in the engine area, but I see burned bare wire across the back of the firewall, in the bundle heading for the battery/voltage regulator area.
Pics here:
http://picasaweb.google.com/scott.kolesar/Wiring#5378941755965890114
I think the wire on the ignition switch was pink. As you can see, BarnStang, the plug is not really a factor, as mine is melted; I'll have to replace it somehow.

 

[BarnStang]

Wow. The wire that got it worst is the Red w/green strip. It looks like it is wire 16 that goes to the coil. You can save the plug, just crimp on a male and female bullet connector to the new wire at the plug to go around it and still be able to disconnect it.

The other wire it took out is the Red w blue strip wire which is wire 32 going to key the solinoid. But I think that is collateral damage, you just need to repair that one.

Oh, yes, on the stock switch the wire that burned is a pink wire, on the new switch is might be red w/ green strip. I see now on my switch I spliced it to the pink wire. Intersting that the wiring book shows it as red w/ grn strip and not pink. Hmmm, there are two sheets for ign, start, charge, gauges. One with a tach and one without. The 70 wiring book is the worst next to the 71-73 book.
View attachment 246379

I think we need to know if your car has a factory tach at this point to make sure we don't fry anything else.

It looks worse than it is. You will have to peel the whole harness apart and make sure all the damaged wires are repaired or replaced-one wire at a time.
Again, you need to know absolutly what caused the short so it doesen't fry the new repaired wiring.

 

[70Mach351c]

The other wire it took out is the Red w blue strip wire which is wire 32 going to key the solinoid. But I think that is collateral damage, you just need to repair that one.

Oh, yes, on the stock switch the wire that burned is a pink wire, on the new switch is might be red w/ green strip. I see now on my switch I spliced it to the pink wire. Intersting that the wiring book shows it as red w/ grn strip and not pink. Hmmm, there are two sheets for ign, start, charge, gauges. One with a tach and one without. The 70 wiring book is the worst next to the 71-73 book.

...I think we need to know if your car has a factory tach at this point to make sure we don't fry anything else.

It looks worse than it is. You will have to peel the whole harness apart and make sure all the damaged wires are repaired or replaced-one wire at a time.
Again, you need to know absolutely what caused the short so it doesn't fry the new repaired wiring.

I'm halfway across the firewall, and about to start peeling tape from the bundle leading from the upper mid firewall to the regulator/solenoid/battery area. To this point it's been easy because the burning wire has melted it. What wire I can see to this point is bare from the ignition switch out across the firewall. It's the circuit you described, it's heading for the solenoid. Marked as 'ignition' in the wiring manual as opposed to starter or accessory. It looks to be the wire that maintains the 'ON' condition of the engine. [excuse the newbie-speak, I'm learning as I go here]

Unconfirmed: the harness may have fallen into contact with the engine, and shorted at that point. I don't see damage in the solenoid/battery/voltage reg. area at the other end of the bundle. At the rate of things around the homestead, it may be next week before I can dig in to confirm.

There is a fleeting reference in the shop manual to the fact that it was pink, but I see by your picture it is red/green. Also, I'll confirm that your switch is opposite of mine as to the bracket mount.

I'll probably need to get up under the dash when I go to repair, at which time I'll probably confirm the rest of the bare wire. For that, I'm probably removing the driver's seat for comfort. and get better task lights. It's going to take time to assess and repair. The previous owner has convinced his daughter (my wife and current owner) that a new harness is not necessary, and "we can fix it". There's no point in trying to sell another solution. I'll have to buy a new fire extinguisher though.

The plug is toast. I can't even separate the halves. I'll check continuity among the other wires across the plug and proceed with the repair. Is it possible to get a new plug and re-splice the cable into it? Surely there's something to put bullet/socket ends onto the wire bundle and snap them into a plug. I will be getting a new harness for on top of the engine, as the current wires are brittle.

PS - I have no factory tach. For that matter, no tach at all.

Before I forget, I appreciate the help here.

 

[2+2GT]

I'm halfway across the firewall, and about to start peeling tape from the bundle leading from the upper mid firewall to the regulator/solenoid/battery area. To this point it's been easy because the burning wire has melted it.

…At the rate of things around the homestead, it may be next week before I can dig in to confirm.

I'll probably need to get up under the dash when I go to repair, at which time I'll probably confirm the rest of the bare wire. For that, I'm probably removing the driver's seat for comfort. and get better task lights. It's going to take time to assess and repair. The previous owner has convinced his daughter (my wife and current owner) that a new harness is not necessary, and "we can fix it". There's no point in trying to sell another solution. I'll have to buy a new fire extinguisher though.

The plug is toast. I can't even separate the halves. I'll check continuity among the other wires across the plug and proceed with the repair. Is it possible to get a new plug and re-splice the cable into it? Surely there's something to put bullet/socket ends onto the wire bundle and snap them into a plug. I will be getting a new harness for on top of the engine, as the current wires are brittle.

PS - I have no factory tach. For that matter, no tach at all.

Don't attempt any further repair while it's on the car. Put nylon zip ties at the branch points, and remove the harness from the car, taping it to a floor where you can solder and shrinktube the repairs. Then use harness tape (NOT electrical tape) to re-wrap the whole thing.

 

[70Mach351c]

Don't attempt any further repair while it's on the car. Put nylon zip ties at the branch points, and remove the harness from the car, taping it to a floor where you can solder and shrinktube the repairs. Then use harness tape (NOT electrical tape) to re-wrap the whole thing.

That is a good piece of advice. I was actually wondering how plain ol' electrical tape could possible last so long without melting. I'd never get this at shows..... I hope to last long enough to pass it on to another neobie.....+1

Hey, I got this sheet of 1/4' ply not doing anthing. I could even hang it on the wall...

I'm within driving distance of Summit Racing. Can you believe these guys have weathertite connectors, split loom, crimp-ons, ties, wire and strippers, but not an inch of tape?

 

[2+2GT]

That is a good piece of advice. I was actually wondering how plain ol' electrical tape could possible last so long without melting.

I'm within driving distance of Summit Racing. Can you believe these guys have weathertite connectors, split loom, crimp-ons, ties, wire and strippers, but not an inch of tape?

1) Electrical tape has glue on it, and the first hot day you park the car in the sun that friggin' glue will ooze out all over the place. Let me know if you need a sourse, my favorite Mustang shop stocks it.

2) Sure, I can believe it. They are into quickies, if your list is any indication. I prefer to solder the connections, then slide a piece of shrinktube over the repair. Then wrap the whole thing in harness tape. It'll work perfectly, for years. I got this habit when I was wiring boats. The slightest bit of moisture in a crimp connector and you've got resistance. This is bad.

 

[BarnStang]

If you have the time and skills to solder correctly, it's the most effective. Correct soldering takes practice and experiance. THe bigger the blob the better the job is not the way to go...I've pitched all the standard crimp connectors and collected a large assortment of heat shrink crimps. THey seal around the insulation when heat shrunk. Expensive, but effective, and if you don't have a good set of crimp pliers, get a set now, you will use them again. ANd not the cheap junk ones that come in the dime store kits. THis is an effective repair within anyones skill range. Here is a link
Heat Shrink Connector (BSA / WBSA) - UTA Auto Industrial Co., Ltd.

And I like this style crimp plier
Channellock® 909 THE CRIMPER Crimp and Cut Tool - ToolKing.com

So, you have some options. You will need to decide what works for you. Practice on some loose wire to get the best connection.

Lowes sells some electrical tape for wire wrapping that I have used before. It's also expensive. And awkward to work with but won't bleed glue. You can alternativly use zip ties just don't pull them tight. Loosly snug. See if I can find the tape again...
Can't find it on the Lowes site yet, but it's also called friction tape or splicing tape.

So where are you with you deconstruction? It may also be easier to pull the inst cluster. ANother hard spot will be where that wire passes through the firewall. You may have to just run a whole new line and aandon the wire in the harness where it passes through the firewall. Once you get it apart you will be able to decide. Just cut all the damaged wire out. Also, you will have to repair/replace any wiring that was damaged cause it ran beside it. As you peel it apart, you will be able to seperate the wires, but the ones that really melted together will tear the insulation off. Some of that you can trim loose with a razor blade, but you will see that some will just be too far gone.

Take some more pictures when you get more of it apart and post them up. I'll also post up some more pictures of the switch. We are prepping for te 70 Boss car coming back from paint and it will need a switch replacement. I'll show you what the Ecklin part will look like out of the box.

 

[BarnStang]

Scotch(R) Premium Vinyl Electrical Tape Super 88

Says it's good to 220 degrees F

It's called Scotch Super 88

Click the link that says "Full Description"

 

[70Mach351c]

Then use harness tape (NOT electrical tape) to re-wrap the whole thing.

Again, I'll start with a "Thanks"

2+2, what's the brand of the tape you talked about? Is it the same as BarnStang's "friction tape"? I saw that at AutoZone, I thought it was some sort of handgrip tape.

I also saw the Super88 - in my toolbox. It's the gooey plastic stuff. Higher quality gooey plastic, it just takes longer to go to goo....

I'm thinking of using the braided fabric material to wrap up my work.

I'll update this weekend. I'm going out to pull a switch from a '70 Cougar (need one?, he says he's got two), and possibly to the Canfield swap meet over in east Ohio.

 

[BarnStang]

Here is some harness tape. Yea, the super 88 isn't as bad, but still has glue. I found this on an MG site...check it out:

MossMotors.com - Restoration Parts And Accessories For British Cars

 

[ddonaca351]

Someplace like Year One or NPD might also have it, for doing concourse quality resto's...