My son tried to start his 70 Swinger today and got a huge ball of smoke from under the dash. Checking things out we found the ground wire that goes to the steering column was fried. Not melted insulation but, copper wire turned to ash fried. The key switch seemed a bit stiff to turn and didn't want to spring back from start to run. I haven't had a chance to check anything else out yet. This car has the usual amounts of hacked wiring. The wires at the bulkhead connector looked ok. I haven't checked the wires at the ammeter yet. Haven't done the Madelectricle fix on it yet either. Might be time to do it. Anyone seen a ground wire burn up like that?
Dead short?
- Thread starter 70net440
- Start date
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67Dart273
Well-Known Member
Without knowing "what wire" you are talking about, very very hard to say
Here is the 'massive shorts' strategy
(This can get complicated FAST when somebody has hacked up factory wiring)
First, you need to protect against further damage.
So "get" some stuff
If you don't already, get a multimeter, a 12V test lamp and a bag of clip leads from Radio Shack (if they are still in business)
Get a factory service manual. You can download them here
http://www.forabodiesonly.com/mopar/showthread.php?p=1970088617
http://www.mymopar.com/index.php?pid=31
and, READ this article. It gives you good insight and a simplified diagram of the basic power distribution
http://www.madelectrical.com/electricaltech/amp-gauges.shtml
Also, get yourself a "heavy" test lamp. This can be an old headlight that works, or an old stop / tail light socket with an 1157 bulb. You can hook the wires together in different ways for more or less wattage
THEN remove the battery ground, and hook your "heavy" test lamp IN SERIES with the ground cable
THIS gives you an indication of current flow, while providing protection. That is you can "throw a wrench" across the alternator output stud and all that will happen is your test lamp will light up bright!!!
You won't smoke anything more this way.
===========================================
Now I'm gonna give you some bad news. From what you describe with the ignition switch, it just might be that you have suffered a major short, and the wiring in the harness, BOTH in the engine bay and under the dash, has melted itself together and caused more (welded) shorts.
Hook up your series test lamp. Get a light? Check everything, make sure everything is OFF and make sure the trunk light hood light (if present) and most certainly the dome light is out.
Still have a light?
Pull the fuses one at a time and see if that "kills" the light
No?
Unbolt and tape off the alternator output wire, does that do anything?
If not, this could be trouble.
Go inside and pull the ignition switch connector apart. Still have a light?
Might be time to pull it apart. Drop the column, pull the cluster, and strip the under-dash harness out. Take photos and or tag stuff so you know where it goes.
Pull the engine bay harness out. Unlikely this problem is in the "lighting" or "wiper" hareness, I would not pull them out. But DO examine them visually.
Now, what do you want to do?
1........You can lay out the harness on a bench, nail it down, tie / tape off the branches, and cut loose the wrapping, and inspect the harness and repair it
2.........Find a "good" used harness
3........Spend money and buy a "repop" new harness
4.......Spend money and buy a generic aftermarket harness
Here is the 'massive shorts' strategy
(This can get complicated FAST when somebody has hacked up factory wiring)
First, you need to protect against further damage.
So "get" some stuff
If you don't already, get a multimeter, a 12V test lamp and a bag of clip leads from Radio Shack (if they are still in business)
Get a factory service manual. You can download them here
http://www.forabodiesonly.com/mopar/showthread.php?p=1970088617
http://www.mymopar.com/index.php?pid=31
and, READ this article. It gives you good insight and a simplified diagram of the basic power distribution
http://www.madelectrical.com/electricaltech/amp-gauges.shtml
Also, get yourself a "heavy" test lamp. This can be an old headlight that works, or an old stop / tail light socket with an 1157 bulb. You can hook the wires together in different ways for more or less wattage
THEN remove the battery ground, and hook your "heavy" test lamp IN SERIES with the ground cable
THIS gives you an indication of current flow, while providing protection. That is you can "throw a wrench" across the alternator output stud and all that will happen is your test lamp will light up bright!!!
You won't smoke anything more this way.
===========================================
Now I'm gonna give you some bad news. From what you describe with the ignition switch, it just might be that you have suffered a major short, and the wiring in the harness, BOTH in the engine bay and under the dash, has melted itself together and caused more (welded) shorts.
Hook up your series test lamp. Get a light? Check everything, make sure everything is OFF and make sure the trunk light hood light (if present) and most certainly the dome light is out.
Still have a light?
Pull the fuses one at a time and see if that "kills" the light
No?
Unbolt and tape off the alternator output wire, does that do anything?
If not, this could be trouble.
Go inside and pull the ignition switch connector apart. Still have a light?
Might be time to pull it apart. Drop the column, pull the cluster, and strip the under-dash harness out. Take photos and or tag stuff so you know where it goes.
Pull the engine bay harness out. Unlikely this problem is in the "lighting" or "wiper" hareness, I would not pull them out. But DO examine them visually.
Now, what do you want to do?
1........You can lay out the harness on a bench, nail it down, tie / tape off the branches, and cut loose the wrapping, and inspect the harness and repair it
2.........Find a "good" used harness
3........Spend money and buy a "repop" new harness
4.......Spend money and buy a generic aftermarket harness
hey 70net
67dart has given you some excellent advice. i would add a bit more information as i've had a few wiring problems on my 68 barracuda created primarily from the prior owner installing a "viper" anti-theft system. DO NOT EVER install a modern anti-theft device on an old mopar!! these devices are made to hook up to a number of electric circuits and removing one is a nightmare!!
now as to some advice...
i made photo copies of the engine compartment, interior and dash wiring diagrams from the OEM 68 plymouth service manuel i have. wiring diagrams are VERY hard to follow so here's what i did. i got about six different color fine point felt tip markers and traced each wire with a different color marker. by doing this you can see where the wires go from all of the major electric systems i.e.... starter, dash gauges, wiper motor, lights, etc. i would follow every major wire to see if you can find a connection and/or wire that is shorted out or melted. if you are having a lot of trouble finding your short you might try installing "in-line" fuses on wires leading to major electric components. i burned out a fine OEM turn signal switch on my barracuda from trying to track down a short. i did have an original replacement switch and when i installed that one, i installed in-line fuses on each of the six wires so there would be no chance of frying that switch. in-line fuse holders are a bit bulky but you can usually hid them under the dash or behind a component.
i HATE electrical problems. tracking down shorts requires a LOT of patience and a wiring diagram showing how the wires SHOULD be hooked up.
finally, as most guys will tell you, if you cannot find a short you likely have a power feed wire with the insullation worn off allowing it to short out on the frame, chassis, firewall, component, etc. don't forget to look for a "bare" wire anywhere and everywhere.
67dart has given you some excellent advice. i would add a bit more information as i've had a few wiring problems on my 68 barracuda created primarily from the prior owner installing a "viper" anti-theft system. DO NOT EVER install a modern anti-theft device on an old mopar!! these devices are made to hook up to a number of electric circuits and removing one is a nightmare!!
now as to some advice...
i made photo copies of the engine compartment, interior and dash wiring diagrams from the OEM 68 plymouth service manuel i have. wiring diagrams are VERY hard to follow so here's what i did. i got about six different color fine point felt tip markers and traced each wire with a different color marker. by doing this you can see where the wires go from all of the major electric systems i.e.... starter, dash gauges, wiper motor, lights, etc. i would follow every major wire to see if you can find a connection and/or wire that is shorted out or melted. if you are having a lot of trouble finding your short you might try installing "in-line" fuses on wires leading to major electric components. i burned out a fine OEM turn signal switch on my barracuda from trying to track down a short. i did have an original replacement switch and when i installed that one, i installed in-line fuses on each of the six wires so there would be no chance of frying that switch. in-line fuse holders are a bit bulky but you can usually hid them under the dash or behind a component.
i HATE electrical problems. tracking down shorts requires a LOT of patience and a wiring diagram showing how the wires SHOULD be hooked up.
finally, as most guys will tell you, if you cannot find a short you likely have a power feed wire with the insullation worn off allowing it to short out on the frame, chassis, firewall, component, etc. don't forget to look for a "bare" wire anywhere and everywhere.
Thanks for the tips. I think a new harness with a modern fuse box etc. is the way to go. After I figure out what went wrong in the first place. Looking at Ron Francis or American Autowire. Does anyone know if either of them bypass the ammeter or does this need to be a custom upgrade?
There is a white connector under the column that attaches the switch harness to the dash harness. I suspect you'll find it melted to the point it created a short circuit.
Other circuits like the shift indicator lamp and switch light time delay really shouldn't have been placed in that same connector but they were. Those are the circuits that relate the little ground jumper at column mounting.
FYI The horn circuit uses that ground jumper also but it's in the other connector to signal switch.
Other circuits like the shift indicator lamp and switch light time delay really shouldn't have been placed in that same connector but they were. Those are the circuits that relate the little ground jumper at column mounting.
FYI The horn circuit uses that ground jumper also but it's in the other connector to signal switch.
Thanks Redfish. I forgot to mention the short happened when the switch was switched to run before even being turned to start. 67Dart273, great info as always. I really appreciate the help. Now for some spare time and big can of patience.
67Dart273
Well-Known Member
That too, might be a clue. Unfortunately nothing on the "run" circuit is fused. The only protection is the main fuse link which is no protection at all.
Depends on the year, but what is fed by the run circuit (and of course accessory TO the fuse panel)
is the ignition system, the voltage regulator, and power to the cluster.
In 70, add the blue field lead to the alternator
THIS WOULD BE THE FIRST THING TO CHECK
WHY? Because if the brushes are damaged, or the brush holders, this can create a short right at the alternator field connection(s)
Pull both field wires off. Take an ohmeter, and check to ground. It should be infinate that is, "open" or "no" continuity.
Also the later cars (some) had other stuff added to the 'run' line. Cars with electric choke (suspect), with idle solenoids (some 340s) and retard timing solenoids on the distributors all were fed off the run line, and ARE NOT FUSED
Take a good look at the underhood harness, for any sign of "being hot" under the tape. Look carefully at wiring for melted / "crinkled" insulation
redfastback
Don't ask me... my garage is empty
If your going to replace the harnesses, you can get the factory replacement ones and do the mad electric upgrade on the bench before you install them.
This way you retain all factory end connectors. I did this with mine.
I opened up the engine/fwd harness and took out the voltage reg, ballast wiring, and the ran a new 8 ga wire for the alt. It ran from the alt to the starter relay stud as a main buss point for power. The 2 12 ga wires that come from the ammeter were tied together then ran to that main buss point. Inside I bypassed the ammeter(not necessary now) and had it converted to a voltmeter.
I run a 100 amp 1 wire alt with ZERO ISSUES. Let me know if you have any questions.
I am a dealer for American Autowire and have done many harnesses by them including custom.
This way you retain all factory end connectors. I did this with mine.
I opened up the engine/fwd harness and took out the voltage reg, ballast wiring, and the ran a new 8 ga wire for the alt. It ran from the alt to the starter relay stud as a main buss point for power. The 2 12 ga wires that come from the ammeter were tied together then ran to that main buss point. Inside I bypassed the ammeter(not necessary now) and had it converted to a voltmeter.
I run a 100 amp 1 wire alt with ZERO ISSUES. Let me know if you have any questions.
I am a dealer for American Autowire and have done many harnesses by them including custom.
Finally got a bit of time to do some diagnostic on the Dart. I hooked up a tail light in series with the ground cable from the battery and made a new jumper for the ground that fried on the steering column mount. There are two flat, 8 pin connectors that come from the steering column. With both plugged in, or just the larger connector, I get a bright light. With just the smaller plug connected, I get a very dim light. With both un-hooked, the light goes out. I ran out of time between monsoons to get much further.
BillGrissom
Well-Known Member
1970 has a different column connector than my 1969 Dart had (and current earlier cars). I think you have the key switch in the column. I suggest getting a multimeter (free at HF), gound the black lead, set the 200 ohm scale. With BATT- disconnected (to be safe), touch the red lead to each pin in each connector. If it reads < 5 ohm, make a note. Check a wiring diagram. Some of those might be intended to be grounded (then OK). If a supply wire, it is probably shorted to ground. A 15 W bulb would measure > 10 ohm [P=(V^2)/R].
Did some checking with the ohm meter. I found one yellow wire in the ign switch harness that showed 35 ohms. The wire is separated from the other wires and has a butt splice just up from the factory connector. This makes me think there were problems before. None of the other wires in either harness in the column showed continuity to ground. Looking online, the replacement ign switch and turn signal switch seem to have different connectors than what I have. This car has two flat 8 pin connectors with round female terminals and 8 wires in each connector. Also, it seems the turn signal switch is a new Chrysler only item. Any thoughts?
nm9stheham
Well-Known Member
Are you measring the 35 ohms back into the car harness side of the ignition switch connections? If so, then the yellow wire to the car harness goes to the starter relay coil and 35 ohms seems resonable if you have an auto with it in park or neutral when you tested.
I am catching up with what has been done. Do you have a new ignition switch installed?
Have you carefully examined the wires on the ignition switch harness up into the column? Shorts there seem somewhat common.
Your prior test with the test lamp shows that the main harness to the ignition connections are free from shorts; that is good.
With the ignition connectors disconnected, and the test lamp in the battery - lead, connect a jumper between the ignition harness connectors on the black lead only. This will put 'juice' to the ignition switch but nothing out. Check to see if your test lamp glows. If yes, then the ignition switch input or wire is shorted. If not, then turn the key to all positions to see if the light glows indicating a short in the switch when in certian positions or to an output wire in the switch. With the column ground burning out and the bad switch action, it may well be that the ignition switch was shorting in some or many positions.
If all OK, then put the ignition switch in the RUN position and one by one, jumper the others wires between the ignition connectors and record what lights and how brightly. Some will light a bit (like the dark blue ignition circuits). Let us know what you find.
I am catching up with what has been done. Do you have a new ignition switch installed?
Have you carefully examined the wires on the ignition switch harness up into the column? Shorts there seem somewhat common.
Your prior test with the test lamp shows that the main harness to the ignition connections are free from shorts; that is good.
With the ignition connectors disconnected, and the test lamp in the battery - lead, connect a jumper between the ignition harness connectors on the black lead only. This will put 'juice' to the ignition switch but nothing out. Check to see if your test lamp glows. If yes, then the ignition switch input or wire is shorted. If not, then turn the key to all positions to see if the light glows indicating a short in the switch when in certian positions or to an output wire in the switch. With the column ground burning out and the bad switch action, it may well be that the ignition switch was shorting in some or many positions.
If all OK, then put the ignition switch in the RUN position and one by one, jumper the others wires between the ignition connectors and record what lights and how brightly. Some will light a bit (like the dark blue ignition circuits). Let us know what you find.
Pete in NH
Well-Known Member
Hi,
On the turn signal switch the original Chrysler P/N was 2947503 that supersedes to 4293102. The later number fits A,B and C body cars so it will have a cornering lamp switch connector you will not use. Your local Chrysler dealer should be able to get it for you or I'm sure you can find it on line.
I think you should track through the tests that were suggested by nm9stheham before tackling the turn signal switch.
On the turn signal switch the original Chrysler P/N was 2947503 that supersedes to 4293102. The later number fits A,B and C body cars so it will have a cornering lamp switch connector you will not use. Your local Chrysler dealer should be able to get it for you or I'm sure you can find it on line.
I think you should track through the tests that were suggested by nm9stheham before tackling the turn signal switch.
I have not installed a new ignition switch yet. I was testing the wiring from the switch inside the column not out to the car. My thinking on the turn signal switch was that, I need to nearly remove it to get the ignition switch so I might as well replace it too. There are couple sketchy wires in the turn signal harness right near the connector also even though they didn't show any shorts.
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