Losing switched power and other #$%&^# electrical issues. HELP!

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Mopar to ya

Mopar to ya

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I need some help. My 73 Dart Sport, 408 stroker / 200 4R, has been running great for 6 years. A month or so I came home from a car show and it would not shut off. Key turned off, key in hand, but it stayed running. I didn't notice it before, but I drove it a week later and noticed it wasn't charging as well. It seemed like it was the ignition switch, so I installed a brand new one. Same issue. I had 12.6v at the battery and only 10.8 at the alternator. I started tracing the power to the alternator and after a little checking I found the car wouldn't start. The MSD ignition wasn't supplying power to the coil. I had constant power and ground, but I found the switched power to the MSD had 12v key on, but lost all power during cranking. If I added 12V to the switched line the car starts. I draw the switched power from the ballast resistor, and have since I put the motor in. I have key on power at all four terminals but lose power to all four when cranking. It seems to me that my new ignition switch is bad, but I am looking for opinions, ideas, etc. When I ran power to the MSD box and got it running today it still wouldn't turn off with the key and was not charging. I have to believe they are all related and that in the end one repair will fix all the issues. HELP!
 
I have 12V at all four terminals key on, but lose all power to all four terminals on cranking. I jumpered the ballast years ago, it supplies full power, not stepped down power. At least when everything is working. I replaced the ballast anyway since I had one. No surprise, it made no difference.
 
Mopar to ya said:
I have 12V at all four terminals key on, but lose all power to all four terminals on cranking. I jumpered the ballast years ago, it supplies full power, not stepped down power. At least when everything is working. I replaced the ballast anyway since I had one. No surprise, it made no difference.
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Got it. Are you using the original/factory cranking power source wiring config? If so I can trace it back in my 73 fsm and figure out where to check for power next. I know you're not all factory from your original post, but id be happy to do that for you.
 
The only two terminals on the ign switch that will be hot "cranking" is the yellow start wire and the old brown ignition bypass, "IGN2"

Both accessory and ignition "run" go dead during cranking. This is why you hear all the talk about jumpering IGN1 and IGN2 (traditional blue and brown) together when eliminating the ballast.

Your small red on your MSD is a "trigger" wire sort of like a relay coil.
 
67Dart273 said:
The only two terminals on the ign switch that will be hot "cranking" is the yellow start wire and the old brown ignition bypass, "IGN2"

Both accessory and ignition "run" go dead during cranking. This is why you hear all the talk about jumpering IGN1 and IGN2 (traditional blue and brown) together when eliminating the ballast.

Your small red on your MSD is a "trigger" wire sort of like a relay coil.
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That is interesting. I'll check the yellow and brown wires. Everything in the car seems to go dead on cranking, but I will physically check those two. Without cranking power to the red MSD wire the box didn't see hall effect and won't fire the coil. One I run direct power to that red wire the car starts and I can see the light in the MSD box flashing with each hall effect trigger.
 
Okay, the yellow and brown have power only during cranking. No key on power. The brown wire was cut of my factory harness and wasn't being used. I ran a wire from the MSD box to the yellow wire and the car started but the starter drive remained engaged the entire time it ran. If I run the wire to the brown wire, the car starts and will also shut off with the key. One problem solved. However, I an still not charging and show 10.6v at the alternator B+.
 
I don't know how you ran it "before." Using the yellow wire could cause a feedback situation. There are only so many ways to get around this, as the "run" wire has always gone cold during crank

1....Rewire the brown so it's functional and jumper to the blue "run" You can do that either in the bay or under the dash

2....you could run a diode between the start terminal (yellow) and the "run" to isolate them, but with RadioShXXt being pretty much dead, just getting a diode is tougher.

3....you could parallel a second relay to trigger with the start relay and use the contacts to route starting voltage to the MSD
 
Tab wire from brown along with switched power to MSD box. Starts, runs and turns off. Still not charging. Only 10.6v to the alternator. My brother wants to go to a car show tonight and says cheat and run power from your battery to the alternator. I said no one likes a cheater, and he said cheaters always win. Hard to argue that, so I ran the power. Still no charging and now the car won't shut off with the key again. I removed the power wire to the alternator and it shut off with the key.
 
Whenever i have an electrical problem, I make sure my grounds are super solid first, then I address the stuff 67dart273 is talking about.... just a good practice thing. It probably isn't the ground, but I check em....all of em. F'n grounds have fooled me before I won't be fooled again.

$O.o2
 
What are you using for an alternator/ regulator? If this is a GM "3 wire" you need a diode or lamp or resistor in series with the excitation wire from the "key"

With the problem "active" try pulling the small red loose from the MSD and if it kills the engine, AND THEN the "run" wire is cold after engine stops, then this has GOT to be some sort of backfeed issue.
 
Pretty sure I found it. Now if I can just figure which wires go where. There are a lot of spliced wires in this spot and aren't factory colors. Only one is power, and I know the alternator b+ goes to that.
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Sorry you are on your own. That does NOT look like fun.
 
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