Electronic ignition troubleshooting help

Electrical & Ignition

  1. Curt Chambers

    Curt Chambers Well-Known Member

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    Tried to fire up my 73 Charger Rallye, 440, 4 speed today and it wouldn't start. This is my first attempt at starting the car after a complete restoration, so any number of things could be going on.

    But there is definitely no spark so let's start with that. I have an FSM, but its troubleshooting section assumes I have the factory test unit available, which I don't. So using a voltmeter, I have 10 .5 volts at the coil with the ignition in the run position. Is that too low? It's a brand new battery and I verified 12.5 volts going to the ignition switch. There was a 1v drop going through the switch and another 1v drop at the bulkhead connector in the engine bay, for a total of 2v drop at the ballast resistor. The troubleshooting steps I found on the web all said that it should be within 1v of the battery voltage.

    Would it be safe to run a wire directly from the battery to the ballast resistor to test this, to see if it at least momentarily tries to start?

    Is there a way to test the ECU without the factory tool? All I could find was to make sure it is well grounded, which it is.

    Thanks
    Curt
     
  2. Ranger16

    Ranger16 Well-Known Member

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    Any chance you have the run and crank wires inverted on the ballast resistor?

    Easiest way is to swap it out with your spare. You do carry a spare, don't you?
     
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    • tonysrt

      tonysrt Well-Known Member

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      Did you check the voltage at the ballast when your cranking with the ignition switch? If you jump 12volts to coil it should start if ignition switch isn't giving you 12 in start.
       
    • Curt Chambers

      Curt Chambers Well-Known Member

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      I didn't check cranking voltage. With only 10.5 available to the ignition system I didn't think it would matter. Is the ignition switch switch resistance less in the start position?

      I wired the ballast resistor according to the diagram in the FSM. I'm pretty sure the Ign1 and Ign2 connections are correct. However, the FSM shows a jumper wire from Ign1 to the auxillary side of the resistor and mine doesn't have that. FYI, the voltage going into the ECU is the same as everywhere else, 10.5v
       
    • 65wgn440

      65wgn440 Well-Known Member

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      I would check voltage at + coil terminal while cranking. 10.5 should still start it. Check for a trigger voltage at coil - terminal while cranking ( test light blinking). If you have both of those, check for spark at coil wire coming out of coil. If no, coil or coil wire bad. If yes, dist cap, dist rotor, dist not turning. If no trigger, box, pick-up, wiring problem possible.
       
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      • Curt Chambers

        Curt Chambers Well-Known Member

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        Thanks, those are good suggestions. Didn't know about checking trigger that way. Will post back with results.
         
      • Curt Chambers

        Curt Chambers Well-Known Member

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        9.1v cranking at the coil. Test light at the coil - to ground did not blink while cranking (stayed lit). And there was no spark at the coil high tension lead. So basically it failed all the tests.

        Time to break out the parts cannon. Which is most suspect at this point, the ICM?
         
      • Don Frelier

        Don Frelier FBBO Gold Member FBBO Gold Member

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        You need the jumper on the dual ballast.
        Your not powering the ECU without it. 1714629349.jpg
         
      • RemCharger

        RemCharger Well-Known Member

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        Is your ign box a 5 pin to match the above diagram.
         
      • Curt Chambers

        Curt Chambers Well-Known Member

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        Good point. I repeated the test with the jumper wire attached but the results were the same.
         
      • Curt Chambers

        Curt Chambers Well-Known Member

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        No. It's only a 4 pin. According to the parts catalog that's what it is supposed to be.
         
        Last edited: Jan 10, 2021
      • RemCharger

        RemCharger Well-Known Member

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        Then what is the other side of the dual ballast going to?
         
      • Curt Chambers

        Curt Chambers Well-Known Member

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        The harness that came with the box has 5 wires and I connected them all. But the box itself only has 4 pins.
         
      • RemCharger

        RemCharger Well-Known Member

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        Right. So its going to nothing.
        Can you post a pic of your wiring
         
      • Don Frelier

        Don Frelier FBBO Gold Member FBBO Gold Member

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        Check the gap on your pickup coil and reluctor.
        If you have another loose distributor you can plug it in and spin the shaft and check for spark from the coil wire.
        It could just be the pickup coil adjustment or the pickup coil could be bad.
         
        Last edited: Jan 10, 2021
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        • Curt Chambers

          Curt Chambers Well-Known Member

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          I will but it's all a bit of a mess right now trying to troubleshoot. The missing pin on the box still has a wire coming out which is connected to the ballast resistor as per the diagram in post #8 (the green wire in the diagram). I have no idea what its purpose is. I figured it wasn't important since the catalog lists a 4-pin box for a 72-74.
           
        • Curt Chambers

          Curt Chambers Well-Known Member

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          OK, I will make those checks tomorrow and report back. A little bit of history might help here.

          I purchased the car a few years ago in a non-running condition. During the course of complete restoration it was discovered that someone had installed a points ignition system on the vehicle at some time. So I purchased an electronic distributor, coil, ICM, and harness from a vendor on this site. I wasn't interested in anything fancy, just a basic system that worked. The components are probably used (they don't look new or NOS), but I assumed everything was in a working condition since that is what I had asked for. But that was a couple years ago and I'm just now getting around to dealing with it so it's probably my fault for not verifying things at the time.
           
        • Curt Chambers

          Curt Chambers Well-Known Member

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          I'm going to be out of town for a couple days and wont' be able to work on it. In the meantime I wanted to ask if the 4-pin box I have is correct for this vehicle, or if I need to look for 5-pin box. Thanks.
           
        • MoparLeo

          MoparLeo NRA PATRON LEVEL LIFE MEMBER FBBO Gold Member

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          • Curt Chambers

            Curt Chambers Well-Known Member

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            According to that article I should only have a single ballast resistor. Now I'm totally confused.
             
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