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Electronic Ignition conversion troubles


Well-Known Member
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2:40 PM
Apr 15, 2016
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I have a 69 plymouth I'm converting to the orange box, new style regulator, and two field alternator. The car previously had a crude engine harness on it wired to an ecu with solid state reg and no alternator. Just enough to get it on a trailer, but mostly ran really well, started on first crank. It came with a brand new oe engine harness. First issue I had after wiring, car would start then stumble and die. I figured out I had to reverse the polarity on the distributor to get it to run. Doesnt seem right to me.

Next thing, the car was running without an alternator when I got it. As I was trying to troubleshoot all this, I noticed it won't run without the alternator hooked up anymore. It would only start with the key in the start position. I replaced the ballast resistor. Same thing. You hook up the alternator and it fires right up, but runs sorta rough. Battery has 12.5 volts also. Is that right?

I've tried multiple coils, ballasts, and ecus
Check for power coming from your ignition switch in the Run position. I had a 69 that had a loose ignition switch that way.
also check to make sure that the dark blue wire coming from the ignition switch has 12v coming to it to the ballast. you can do this first with the key in the run position. If there is 12 volts or so there you dontnhave to check the ignition switch itself.

do this and report back
Sounds like something to do with power from and to the alternator. Hot to the starter from the battery. Hot from the battery to the starter relay, Hot from the starter relay to the small post on the starter. You might want to purchase a new engine harness and start over with the correct connections.
If you put the 12v wire to the orange box on the 6v side of ballast resistor that will cause problems.
Sounds like 50+ yrs of wiring problems/changes & re-wiring those ccts will probably fix your problem.
Update. I did have a loose connection at the switch! I took my brand new distributor out and put the old one back in, car runs like a top again. I'm still not getting charge from the alternator though. The alternator I'm using is a square back that had one field terminal clipped to be used on a single field with solid state (I posted about this in another thread) I isolated that terminal and wanted to use it on this car (it's brand new). Well it's not charging. Thinking I may just go buy the right alternator.