Engine stays running without key in ignition (and more!)

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Righty Tighty

Righty Tighty

Blame it on the dog
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I guess the Scamp decided it didn't want to be my semi-daily driver anymore, so it quit on me.

The other day, I took her into town to run some errands. About 20 minutes into the trip, driving about 65-70 mph on the interstate, it began to run a little hotter than normal (230F). The outside temp was about 108F, so I figured it may have been the heat. I kept it slow and continued the trip. I also noticed the ammeter was dancing around in the mid-range. On my way back home about 2 hours later, the ammeter spiked. It remained pegged for about 3 minutes, then eventually worked its way back to normal.

When I got home, I turned the key to kill the ignition, but the engine stayed running. I popped to hood to disconnect the ballast, still running. So I pulled the coil wire and that killed the engine. I looked over the wiring to see if I could see anything obvious, and the first thing that caught my eye was the coil was leaking oil. Stock type coil, came with the car when I bought it 2 years ago, mounted horizontally on the intake.

I already had a newish MSD Blaster 2, so I swapped the damaged coil for the MSD. I realized I was already running the ballast resistor that came with the MSD (.8 ohms), so I kept it installed. Started the car and pulled into the driveway to put her in for the night, still couldn't kill the engine with the key, but now the dash lights are stuck on and the engine runs very poorly with any throttle whatsoever. The dash lights may have been stuck on earlier in the day, maybe I just didn't see them in the sunlight.

Another thing I noticed when looking things over, was that the positive battery cable to the starter had fallen against a header. It wasn't terribly damaged, but the insulation was melted a bit. Made me wonder if the (+) cable made contact with the wire that goes to the starter relay, since they are paired together.

Here's my setup and the pertinent components I can think of:
71 Scamp, 318LA, older stock coil, newer orange ECU w/ Mopar distributor, new voltage regulator, new alternator (Vision OE 7509), new engine harness, new battery.

I'm admittedly pretty ignorant with automotive electronics, so bear with me if there's something obvious that I've missed. Tomorrow I will be using my multimeter to check the wiring, but I'm not really sure where to start. Any help is greatly appreciated.
 
First thing that comes to mind is you have melted some wires together under the dash.

Download your wiring diag. from mymopar.com
 
Thanks! Thankfully I've already downloaded both the body and chassis service manuals for my car. I will reference them.
 
Start tracing out the wires from the ballast to the ignition to the battery etc.
 
The ammeter spiking which way?
This is a big clue.
 
Righty Tighty said:
Another thing I noticed when looking things over, was that the positive battery cable to the starter had fallen against a header. It wasn't terribly damaged, but the insulation was melted a bit. Made me wonder if the (+) cable made contact with the wire that goes to the starter relay, since they are paired together.
Click to expand...

IF that wire (the copper inside) touched the headers, then it grounded.
If it touched the threaded terminal on the starter relay that would just be a second path, no big deal. They both connect to the battery positive.

So far the only "rookie mistake" was not routing and securing the cables like the factory did. Lots of us have done that. Anyway, take a look at how the factory supported the wires and copy that when you solve the problem and get things back together.

Although not a rookie mistake, in general shut down the car immediately upon pegging the ammeter if you can. Something has gone wrong and way too much current is either going out of the battery or toward the battery. Either way there is a major problem and its best to find it.


Righty Tighty said:
newer orange ECU w/ Mopar distributor, new voltage regulator, new alternator (Vision OE 7509), new engine harness, new battery.
Click to expand...
Did this car come with a points or an electronic ignition?

Here's a 70-71 power scheme with a ECU added.
upload_2021-7-5_20-16-17.png

It's possible the ignition run or start wire got melted to the wire supplying the switch. Check the connector and in the steering column itself.
 
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Righty Tighty said:
It spiked all the way to the positive side (to the right).
Click to expand...
Right is Charge.
That means over 40 amps was going toward the battery. That's definately possible if the cable to the starter shorted to ground.
Check the condition of the fusible link. Unfortunately it doesnt melt fast with 'only' 50 or even 60 amps.

I'd disconnect the battery and see if it wil lcharge on a charger.

Then start hunting cross wire short from any of the power supply wires to the ignition wires (labelled J2).
You can use the ohmeter function as long as the battery is disconnected.
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The ammeter is always positive. Its attached on one side to the battery positive and on the other side to the alternator positive.
When the battery is supplying power to the system, the ammeter shows discharge.
When the battery is getting charged, the ammeter shows charging.
In normal driving the ammeter should be centered unles the battery was low and needed charging.


Black wires in the diagram above are alternator output wires. They will be at the some voltage as the battery, or when the engine is running, the alternator.
 
Mattax said:
IF that wire (the copper inside) touched the headers, then it grounded.
If it touched the threaded terminal on the starter relay that would just be a second path, no big deal. They both connect to the battery positive.

So far the only "rookie mistake" was not routing and securing the cables like the factory did. Lots of us have done that. Anyway, take a look at how the factory supported the wires and copy that when you solve the problem and get things back together.

Although not a rookie mistake, in general shut down the car immediately upon pegging the ammeter if you can. Something has gone wrong and way too much current is either going out of the battery or toward the battery. Either way there is a major problem and its best to find it.



Did this car come with a points or an electronic ignition?

Here's a 70-71 power scheme with a ECU added.
View attachment 1715760977
It's possible the ignition run or start wire got melted to the wire supplying the switch. Check the connector and in the steering column itself.
Click to expand...
I'm going to check the cable tomorrow, but I wouldn't be surprised at all if some bare wire did indeed touch the header. And I appreciate the tip to properly secure the cables -- I honestly don't know why I didn't do that in the first place.

The car came with points ignition, and I converted it to electronic. The schematic looks like what I have wired, with one component in question which I have circled. What is it?
55430379-CA4D-4A06-9135-1E68875A4EAE.png


Mattax said:
Right is Charge.
That means over 40 amps was going toward the battery. That's definately possible if the cable to the starter shorted to ground.
Check the condition of the fusible link. Unfortunately it doesnt melt fast with 'only' 50 or even 60 amps.

I'd disconnect the battery and see if it wil lcharge on a charger.

Then start hunting cross wire short from any of the power supply wires to the ignition wires (labelled J2).
You can use the ohmeter function as long as the battery is disconnected.
-------

The ammeter is always positive. Its attached on one side to the battery positive and on the other side to the alternator positive.
When the battery is supplying power to the system, the ammeter shows discharge.
When the battery is getting charged, the ammeter shows charging.
In normal driving the ammeter should be centered unles the battery was low and needed charging.


Black wires in the diagram above are alternator output wires. They will be at the some voltage as the battery, or when the engine is running, the alternator.
Click to expand...
Thanks so much for the education. I knew the ammeter had something to do with the condition of the charging system, but didn't quite understand how it worked or what it indicated.

I'm going to do what you suggested and start checking the wiring tomorrow, as well as throw the battery on the charger and see how it does.
 
Righty Tighty said:
I popped to hood to disconnect the ballast, still running.
Click to expand...
So, you're saying that you disconnected the wires from the ballast and the car still ran?

The coil gets power from two places. During "run" it gets power from the blue wire that goes through the ballast. During "start" the ballast is bypassed and the coil gets a full 12v from the brown wire. The brown wire is connected to the blue wire that runs to the coil at the ballast connector.

If you pulled the wires off the ballast, and the engine continued to run, the brown wire has to be shorted to power. It should only have power in "start" but for some reason it has power in "run" as well. Check it with a test light.

If the wires were pulled from the ballast and the engine still ran, it has to be getting power from that brown wire during "run".
 
Well, I disconnected one of the wires at the ballast, which has always worked in the past for killing the engine.

I appreciate the info, looks like my multimeter has a big day today!
 
Burdar's approach is good thinking.

Even though you don't want to reconnect the battery until the problem is identified,
you can approach it the same way using the multimeter set to continuity or ohms.

Establish the baseline first.
Remove the battery from the circuit.
Set the meter to resistance (or continuity).
Attach or hold one probe on the batter positive clamp.

1a.Touch the other probe to the coil. This should show problem condition (continuity) even with the key off. After this you can narrow down where approaching by disconnecting wires.

1b. Touch the other probe to a ground. Check a couple places just to be sure. If it shows a connection then there still is a short to ground.

upload_2021-7-6_11-0-38.png



When you first put the battery on the charger, keep an eye on what the meter or indicators show.


At this point we have to consider the possibility the battery failed internally (plates broke or got lose).
 
Dana67Dart said:
First thing that comes to mind is you have melted some wires together under the dash.

Yup, I suspect one or both of the ammeter wires have fused to other wires in the dash harness. Probably happened when the battery cable hit the exhaust. I'd look real close at the firewall connectors too. You may be in for new harness(es)
Click to expand...
 
That happened to me a couple weeks ago, but I will be damned if I can remember what I did to fix it. when I remember I will let you know.
I think it was a jury rig I did for something else that I had to remove to shut it down
 
Don't discount the idea that the ignition switch itself may have a problem. Before you dig too deep I would access the switch connector, see if the problem exists and then pull the connector off the switch
 
I'm trying to figure out how an ignition switch failure would turn on the dash lights.....
 
Do you have an electric or direct drive fan on the car?
 
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No argument there. Shorts and dead grounds can cause all sorts of problems. Add 50 years to the components and you may be chasing gremlins for months.
 
Thanks for all the replies. I had to repair the air compressor, so it and all of its parts were taking up shop space and my time so far this week. I've got a good feeling I'll be able to get after this at some point today.

67Dart273 said:
Don't discount the idea that the ignition switch itself may have a problem. Before you dig too deep I would access the switch connector, see if the problem exists and then pull the connector off the switch
Click to expand...
Thanks. I've got a new battery cable on the way, so while I wait I'll take a look at the switch connector (and all the other things mentioned.....). I agree when you said it's possible there's more than one problem. Most of the electrical hasn't been replaced, and a lot of it has had some janky work done to it, even to my untrained eyes. Honestly, I'm surprised it took this long to have an electrical issue.

RustyRatRod said:
Do you have an electric or direct drive fan on the car?
Click to expand...
I have a mechanical, clutch type fan with a shroud.

cudamark said:
you may be chasing gremlins for months.
Click to expand...
I suspect you may be right. The good news is that this will help teach me how to troubleshoot electrical problems!! Something that has mystified me for years.

Thanks for the help, everyone, I'll report back with what I find.
 
Righty Tighty said:
I have a mechanical, clutch type fan with a shroud.
Click to expand...

Otay. Just for kicks, try disconnecting the alternator electrically from the system and see if it still runs on after the key is cut off. Humor me. It will only take less than five minutes.
 
Well, this is why electronics mystifies me. I was going to conduct Rusty's experiment first, since it was the simplest and was the least invasive, then go from there. I connected the battery negative, and heard a tick. Repeated this and heard the tick again. I narrowed the noise down to around the blower motor area near the firewall. I noticed the connection between the engine harness and blower motor was loose, if connected at all, so I ensured a proper connection. Started the car and let her warm up, then shut it off - same run on problem. I started it and tried the same procedure, but this time the car shut off with the key. Tried again, shut off with the key again. Again, again, again. I can't replicate the problem anymore.

I disconnected the blower motor connection and the car still shuts off as it's supposed to (I know, the blower motor has nothing to do with the ignition, but that was the only variable where I saw change). I disconnected the alternator, still works fine - starts and shuts off as it's supposed to.

Now obviously, something changed somewhere. But where?? I did relocate the positive battery cable away from the header, so maybe that corrected a ground issue? I don't know. The dash lights are still on, so not all is well and good in the world, but at least I'll be able to sleep a little better tonight.
 
Righty Tighty said:
Well, this is why electronics mystifies me. I was going to conduct Rusty's experiment first, since it was the simplest and was the least invasive, then go from there. I connected the battery negative, and heard a tick. Repeated this and heard the tick again. I narrowed the noise down to around the blower motor area near the firewall. I noticed the connection between the engine harness and blower motor was loose, if connected at all, so I ensured a proper connection. Started the car and let her warm up, then shut it off - same run on problem. I started it and tried the same procedure, but this time the car shut off with the key. Tried again, shut off with the key again. Again, again, again. I can't replicate the problem anymore.

I disconnected the blower motor connection and the car still shuts off as it's supposed to (I know, the blower motor has nothing to do with the ignition, but that was the only variable where I saw change). I disconnected the alternator, still works fine - starts and shuts off as it's supposed to.

Now obviously, something changed somewhere. But where?? I did relocate the positive battery cable away from the header, so maybe that corrected a ground issue? I don't know. The dash lights are still on, so not all is well and good in the world, but at least I'll be able to sleep a little better tonight.
Click to expand...

Ummm.....actually it could have. That's where I was goin with the fan question. Electric motors double as generators when power is cut. If somehow your blower motor was running when the car was and still "hot" when the key was cut off, it could have possibly been spinning producing voltage to the system and keeping the ignition alive. I've never seen it with a blower motor, but have with electric cooling fans when people don't include a relay. I wonder if it's possible the blower relay somehow got stuck and you inadvertently fixed it?
 
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