Smoked some wires today

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72Ruster

72Ruster

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Think i smoked my ignition switch today. 72 Duster 318 3-speed. Car wouldn't start (no crank but brake light on for parking brake) checked battery voltage and it was at 12.8. Arc'd across solenoid and turned over.

After the first time it cranked right up with the key and I went to lunch. Finished eating and went back to the car with no start. Dash light on sometimes but heard some clicking from whatever the solenoid is in the picture over by the glove box. Then wires started smoking and I heard some crackling and arcing in the column.

Would I be correct in diagnosing the ignition switch as the failure?

Electrical stuff worked fine in accessory but burned stuff in start. I've been messing with electrical but not in the column. Had a tach going to the fuse connector on the back of the box and oil/coolant/fuel going to the open fuse spot without a fuse in it.

My tach ground under the dash had popped off but idk if that happened when I was trying to find the smoke or before. Could that have done it? Only recent electrical issue I can think of was a few days ago when the tach didn't work for a second with my door open. Shut the door and it worked fine after that. All Autometer gauges. Unplugged them to see if they were shorting or something but no change and still smoked. It was 110 today and I was in a parking lot so not great pictures. I can take more if it will help diagnose. Thanks in advance and sorry if its kind of jumbled. I'm pretty exhausted.

IMG-2200.jpg


IMG-2198.jpg
 
Hard to say what started this but here is what you do to prevent damage

1...One / some wires tend to melt inside the harness sometimes far away from "where you see" So you are going to want to 'plan' on tearing the dash and engine bay harnesses out, untaping them and inspect for "meltage."

2...When troubleshooting "in the car live" protect the system. There are LOTS of circuits in these girls that are not fuse protected. The fuse link is not adequate protection. So round up an old head lamp or tail/ stop lamp socket. Wire the two tail / stop wires together and treat that as one connection. The shell of the lamp is your second connection. Wire this device in series with the battery ground. With everything "off" (don't forget trunk lamp, dome, etc) it should not light. If you encounter a short as you are troubleshooting, your test lamp device will limit current flow, and not melt wires or blow fuses. The worst that will happen is the lamp will light

Obviously you cannot operate the starter with this rig
 
67Dart273 said:
Hard to say what started this but here is what you do to prevent damage

1...One / some wires tend to melt inside the harness sometimes far away from "where you see" So you are going to want to 'plan' on tearing the dash and engine bay harnesses out, untaping them and inspect for "meltage."

2...When troubleshooting "in the car live" protect the system. There are LOTS of circuits in these girls that are not fuse protected. The fuse link is not adequate protection. So round up an old head lamp or tail/ stop lamp socket. Wire the two tail / stop wires together and treat that as one connection. The shell of the lamp is your second connection. Wire this device in series with the battery ground. With everything "off" (don't forget trunk lamp, dome, etc) it should not light. If you encounter a short as you are troubleshooting, your test lamp device will limit current flow, and not melt wires or blow fuses. The worst that will happen is the lamp will light

Obviously you cannot operate the starter with this rig
Click to expand...
Ok ill see if I can rig something like that up. Going to go ahead and order a new ignition switch. Is it a rough job?
 
72Ruster said:
Dash light on sometimes but heard some clicking from whatever the solenoid is in the picture over by the glove box.
Click to expand...
This?
img-2200-jpg.jpg

It looks like a horn relay, but more often that's on the left cowl.
And yes its an electromechanical solenoid relay. Just so you know, in automotive speak usually 'solenoid' is reserved for the one that actuates the starter engagement.

A '72 Dodge Chassis or Plymough Service manual may have a connector identification table.
This snip is from '73 Dodge as an example of one that does.
upload_2020-8-17_21-28-19.png


CI = Connector Instrument Panel
The first letter-number on a wire is the circuit and wire section. M appears to be Map. A is battery, R is alternator, J is run & ignition. Q is accessory power. S is start
Next group on the wire label is SAE wire gage followed by color. 20P is 20 ga Pink. 20BR/Y* is 20 gage Brown with Yellow trace (stripe)

If you have decent internet and a computer, mymopar.com has free scans of many service manuals in the 'reference' subsection. IIRC there is a '72 in there.
They also have seperate electrical diagrams, but those are non-factory and generally not as accurate or complete.
 
Mattax said:
This?
View attachment 1715580124
It looks like a horn relay, but more often that's on the left cowl.
And yes its an electromechanical solenoid relay. Just so you know, in automotive speak usually 'solenoid' is reserved for the one that actuates the starter engagement.

A '72 Dodge Chassis or Plymough Service manual may have a connector identification table.
This snip is from '73 Dodge as an example of one that does.
View attachment 1715580119

CI = Connector Instrument Panel
The first letter-number on a wire is the circuit and wire section. M appears to be Map. A is battery, R is alternator, J is run & ignition. Q is accessory power. S is start
Next group on the wire label is SAE wire gage followed by color. 20P is 20 ga Pink. 20BR/Y* is 20 gage Brown with Yellow trace (stripe)

If you have decent internet and a computer, mymopar.com has free scans of many service manuals in the 'reference' subsection. IIRC there is a '72 in there.
They also have seperate electrical diagrams, but those are non-factory and generally not as accurate or complete.
Click to expand...

Yep that's the seat belt relay. Should it click? Never really heard it but the engine is usually cranking when I turn the key lol. Verified the wiring colors. I have the manuals, they're pretty great. Was just in the parking lot when I posted them and didn't have access to them. The hazard flasher over there is pretty badly corroded so Ill grab another one too. Do you think starting with the ignition switch makes sense? Thanks.
 
72Ruster said:
Electrical stuff worked fine in accessory but burned stuff in start.
Click to expand...
Key On, Power to 'Ignition 1' (run) and 'Accessory'
Key in Accessory, Power to 'Accessory'
Key in Start, Power to Ignition 2 (start) and starter relay.

The basic feeds look like this:
upload_2020-8-17_21-48-41.png

Important to know:
The headlights and some of the fuses are always hot. Those circuits work without the key on.
Accessory feed is for wipers, heater fan, and also goes to the fuse box for fused items that require the key to be in run or in accessory.
All the feed wires have no fuse or breaker protection. The fusible link really only protects from a short to ground, if all goes to plan.

72Ruster said:
Had a tach going to the fuse connector on the back of the box and oil/coolant/fuel going to the open fuse spot without a fuse in it.
Click to expand...
Doesn't seem like these would have contributed to the issue. if you want to put a fuse in the open spot for your additional gages, that's not too difficult. That's where a factory tach would be fused.
 
72Ruster said:
Yep that's the seat belt relay. Should it click? Never really heard it but the engine is usually cranking when I turn the key lol. Verified the wiring colors. I have the manuals, they're pretty great. Was just in the parking lot when I posted them and didn't have access to them. The hazard flasher over there is pretty badly corroded so Ill grab another one too. Do you think starting with the ignition switch makes sense? Thanks.
Click to expand...
'72 seat belt relay is just a buzzer, yes?
I haven't had a column switched mopar in ages. But not enough info for me to say begin with that.

I think at minimum I'd start by disconnecting the battery and with the multimeter set to resistance or continuity, see if the switch is internally connecting to the correct wires in each of the positions. Could do that at the column connector and IF that checks out, then check for cross wire shorts downstream.
 
72Ruster said:
Ok ill see if I can rig something like that up. Going to go ahead and order a new ignition switch. Is it a rough job?
Click to expand...

AbodyJoe on here has a nice write up with photos on the "how to." You need a steering wheel puller
 
Was it 4:20 when it happened.

Sorry no help. Just trying to help lift your spirits.

Hope it is a switch or connector and not wires
 
Dana67Dart said:
Was it 4:20 when it happened.

Sorry no help. Just trying to help lift your spirits.

Hope it is a switch or connector and not wires
Click to expand...
It was 4:20 when I got home with the tow. I'm about 80 percent positive it's the switch. Thinking back to this morning the first time I turned it off it kind of stuttered like it still wanted to run. Hadn't done that before and kind of makes sense if some stuff was starting to get crossed. I ordered a new turn signal switch too in case it fried any of that stuff. That had been replaced before judging by the newer plastic and it having the 10 wire setup. Car never had cornering lamps so I can get rid of two extra wires.
 
72Ruster said:
I ordered a new turn signal switch too in case it fried any of that stuff.
Click to expand...
Now your throwing parts at it.
Take a deep breath, draw out the possibilities and check 'em.

You saw smoke so something got very overheated. That requires current, specifically more current than a wire or connector was designed for.
1. You can do what 67Dart273 suggested - look for the overheated wires and connections. I would do that.

2. You can also check the for continuity and resistance. I would do that too.
Facts known.
a. Occured with key in Start position.
b. Overheating occured in column
c. There is a connector in the column & connectors are often weak points.
d. Starter did not turn over - possibly because it wasn't getting sufficient power. (Knowing how the starter soleniod was jumpered would indicate whether there was a short, an open at the relay or the relay was not getting power from the start switch.)


So think about the facts.
Where was the power coming from?
Since it only happened with key in Start;
power clearly was making it to the start switch.
but was it going to the starter relay and ignition, or was it going somewhere else?

Current flow with key in start (not showing the seat belt warning system).
upload_2020-8-18_9-21-41.png



So is there a problem at the switch?
Put the key in Start and check for resistance between the power feed (J1, 12 ga Red) and each output position at the connector.
Should be 0 resistance at Start and Ignition start.
Should be infinate resistance at the others (unless the seat belt thingy gets power from the switch).

upload_2020-8-18_9-34-11.png


Now if you suspect cross wire short to the turn signal switch, you can check that too.

upload_2020-8-18_9-36-54.png


If everything there checks out visually and with your testing, then keep looking for the smoking wire.
It could be the relay wire S2 was grounding or shorting to the chassis or another wire.
It could even be a short to chassis within the starter relay.
 
Mattax said:
It could even be a short to chassis within the starter relay.
Click to expand...
That would look something like this...
upload_2020-8-18_9-47-35.png


Not saying this is what is happening. Just illustrating that possibility to help you think about how a short to ground causes smoke.
That way you can come up with your own checks based on what you find.
 
Mattax said:
Now your throwing parts at it.
Take a deep breath, draw out the possibilities and check 'em.

You saw smoke so something got very overheated. That requires current, specifically more current than a wire or connector was designed for.
1. You can do what 67Dart273 suggested - look for the overheated wires and connections. I would do that.

2. You can also check the for continuity and resistance. I would do that too.
Facts known.
a. Occured with key in Start position.
b. Overheating occured in column
c. There is a connector in the column & connectors are often weak points.
d. Starter did not turn over - possibly because it wasn't getting sufficient power. (Knowing how the starter soleniod was jumpered would indicate whether there was a short, an open at the relay or the relay was not getting power from the start switch.)


So think about the facts.
Where was the power coming from?
Since it only happened with key in Start;
power clearly was making it to the start switch.
but was it going to the starter relay and ignition, or was it going somewhere else?

Current flow with key in start (not showing the seat belt warning system).
View attachment 1715580234


So is there a problem at the switch?
Put the key in Start and check for resistance between the power feed (J1, 12 ga Red) and each output position at the connector.
Should be 0 resistance at Start and Ignition start.
Should be infinate resistance at the others (unless the seat belt thingy gets power from the switch).

View attachment 1715580243

Now if you suspect cross wire short to the turn signal switch, you can check that too.

View attachment 1715580245

If everything there checks out visually and with your testing, then keep looking for the smoking wire.
It could be the relay wire S2 was grounding or shorting to the chassis or another wire.
It could even be a short to chassis within the starter relay.
Click to expand...

I jumped it from terminal B to S from what I can see from the chassis manual. The connectors at the base of the column don't look burned or melted. I'm kind of sketched out to test with it in start because its burning stuff up, and its within a few seconds. Ill be doing the visual first obviously. My reason for buying parts is if I have to take it all apart to find something is burned out then I might as well have the part to replace it. If i don't need the turn signal switch or ignition switch I just return it. Rather do that than find the issue and wait another week to month after that for parts, especially with the current USPS fiasco. Thank you so much for the detailed diagrams. They will be very helpful.
 
That's fine.
72Ruster said:
I'm kind of sketched out to test with it in start because its burning stuff up, and its within a few seconds.
Click to expand...
Resistance tests are done with power disconnected so no danger there.
The only trick will be holding probes while turning the key. Small alligator clips help, or if you have some matching terminals, make up a couple test leads. The terminals on the column connector are similar to common round ones made by Molex.

72Ruster said:
I jumped it from terminal B to S from what I can see from the chassis manual.
Click to expand...
By doing that you bypassed the ignition switch and also bypassed the relay.
So there cauld be a problem in the relay.

B is connection to battery.
S is connection to Solenoid in the starter.
L is power from the key switch in start position.
G is ground for the relay.

upload_2020-8-19_8-20-16.png


When the key is in start and the shifter is in neutral (park), the current can flow through the relay, powering the electromagnet.
upload_2020-8-19_8-27-21.png


The electromagnet pulls the switch closed, connecting B to S.
This powers the starter solenoid.
upload_2020-8-19_8-31-30.png


Likewise when the starter solenoid gets power, it closes a connection direct to the battery to power the starter motor.
upload_2020-8-19_8-33-44.png
 
A short involving wire S2 or terminal L are possible reasons why the starter relay did not work.
 
Mattax said:
A short involving wire S2 or terminal L are possible reasons why the starter relay did not work.
Click to expand...
I checked resistance at the solenoid. Ground was kinda trash so cleaned it up. It was showing about 20 ohms. B and S were in the MOhms, Between the terminals (B to all) was 5 Ohms. Is that normal? My state is kind of on fire right now so progress is slow and my car is covered in ash.
 
Stay safe!
I'll just read what you wrote and type as I go.

20 ohms between what two places? The ground terminal and ground? There should be no connection between ground terminal and ground. In other words it should be infinate or Megaohms. The ground connection should be the wire to the shifter or neutral safety switch, when in N (or Park)
B to ground should be open, which willl show as Meg ohms on many digital meters.
S to ground also should be open.

B should not be connected to any other terminal. 5 ohms between B and anything is too little! Should be infinate! Seems like a problem internally.
If the key was in start, then then there would be a connection between B and L. That connection would be through the key switch and should be 0.1 ohms or less on th e meter.
 
Mattax said:
Stay safe!
I'll just read what you wrote and type as I go.

20 ohms between what two places? The ground terminal and ground? There should be no connection between ground terminal and ground. In other words it should be infinate or Megaohms. The ground connection should be the wire to the shifter or neutral safety switch, when in N (or Park)
B to ground should be open, which willl show as Meg ohms on many digital meters.
S to ground also should be open.

B should not be connected to any other terminal. 5 ohms between B and anything is too little! Should be infinate! Seems like a problem internally.
If the key was in start, then then there would be a connection between B and L. That connection would be through the key switch and should be 0.1 ohms or less on th e meter.
Click to expand...

Here's a photo for reference. 20 Ohms was from the ground terminal to the ring terminal under the bolt. The green wire from the clutch was broken and frayed when I got the car so I grounded that cable out on the firewall. The little red wire was on there when I got it. No neutral safety switch connection I can see but I'm not surprised. Ill recheck the terminals for resistance. Key was not on or in the car when i did the tests.

IMG-2210.jpg
 
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