Duster won't fire in cranking position.

Electrical and Ignition

  1. gliderider06

    gliderider06 Well-Known Member

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    Finally got to the point of starting my 73 Duster. 318, with factory ignition and ECU. I have a 4 pin ballast and also a 4 pin ECU. It only gets spark in the RUN position. Nothing in the START position. Am I missing something? I thought that a 4 pin ecu needed a 2 pin ballast, and a 4 pin ballast needed a 5 pin ecu.
    Any suggestions?
     
  2. Dana67Dart

    Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

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    Did it ever work propperly
     
  3. Rainy Day Auto

    Rainy Day Auto Princess Valiant FABO Gold Member

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    You might have a bad ballast resistor
     
  4. gliderider06

    gliderider06 Well-Known Member

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    I got the car 4 years ago as a shell. Had no wiring or anything. I've been piecing it together since then. Just got to the point for starting the car for the first time today. Everything is new except for the wire harnesses.
     
  5. gliderider06

    gliderider06 Well-Known Member

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    I swapped it and still does the same thing with both ballast resistors. I even ran jumper wires to eliminate the ballast. No luck with it either.
     
  6. Dana67Dart

    Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

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    If you have a wiring diag. start tracing.

    Could be bad or miswired ignition switch.

    Jumper from battery to start side of ballast resistor, if it starts and keeps running it will give you some where to start
     
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    • gliderider06

      gliderider06 Well-Known Member

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      Thanks! I briefly thought about the ignition switch. I do have another one I can swap out of the old steering column.
       
    • 70aarcuda

      70aarcuda Master Hoader of SBM FABO Gold Member

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      dont know if this will help...but
       

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      • 70aarcuda

        70aarcuda Master Hoader of SBM FABO Gold Member

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        jpg instead of pdf

        71DartIgnitionWiring.jpg
         
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        • moparmandan

          moparmandan FABO Gold Member FABO Gold Member

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          This sounds familiar. Read through this see if it helps. Ended up being a bad ECU plug.
          1973 Scamp won't start in start only in run. With a Twist....
           
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          • 67Dart273

            67Dart273 FABO Gold Member FABO Gold Member

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            It helps to understand "how this works." Regardless of whether you have a breaker points or Mopar breakerless ignition, or whether you have a 2 or 4 pin ballast, the one side of the coil resistor that goes to the coil is all wired the same.

            One one end of the resistor is power coming from the switch in "run" called IGN1. IGN1 also branches off some place and feeds the voltage regulator, the alternator field (blue) and some smog du dads depending on year. On the other end which goes to coil+ is power in start which is the bypass circuit called IGN2.

            IGN1 IS ONLY HOT during "run." It goes dead in "crank."
            IGN2 IS ONLY HOT during "crank". It is not present in run. That voltage comes from a completely separate contact on the igntion switch, is brown most years, but varies

            So use a light or meter and check coil + for voltage during cranking. It should be same as battery. If not, "back up" and follow it back (diagram) through the bulkhead to the ignition switch, and check there at the switch, at the connector coming out of the column.

            You can download simplified diagrams at MyMopar as well as service manuals, free
             
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            • Dana67Dart

              Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

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              Would a bad / missing / mis adjusted neutral safety switch cause this or does it intrupt the cranking cir only?
               
            • 70aarcuda

              70aarcuda Master Hoader of SBM FABO Gold Member

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              bad or missing neutral safety switch will not let the engine crank with the key.....provide Ground to the Starter relay switch....
               
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              • 69 340 dart

                69 340 dart Well-Known Member

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                Make sure you have a good ground wire from engine to frame.
                 
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                • gliderider06

                  gliderider06 Well-Known Member

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                  Thank you! I do have a factory diagram, but it doesn't show the ignition circuit like this.
                   
                • Mattax

                  Mattax Just the facts, ma'am FABO Gold Member

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                  Two reasons.
                  One - the diagram in the back of the electrical chapter is just that, a wiring diagram. It shows every wire and connection. The tech was expected to use it for locating wire connections, or when neccessary, to make a schematic. It's actually not that hard and you learn a lot sketching or tracing the circuit you're interested in.
                  Electrical Wiring (Session 247) from the Master Technician's Service Conference

                  Two - Explanations for how individual circuits work are located within the chapter. Additional explanation can often be found in the Master Technicians Conference.
                  Master Technician Service Conference - Chrysler's Training for Mechanics
                  The diagram posted above is for some company's modification. Factory ignition is never powered through the fusebox.
                  @67Dart273 has provided an excellent description of how the ignition is wired in post #11.

                  See post #11
                  Basically, but the logic is reversed. Its the early ECU that needs the second ballast resistor. The original 5 pin ECUs needed their power externally regulated. (If you're not sure which is which, the second resistor is 5 ohms)

                  The resistor does act as a connection to the ECU. But because it is sparking in Run, the resistor must be OK. The purpose of the 'Ignition 2' circuit is to bypass the ballast resistor during start so the coil gets unreduced battery power.
                   
                  Last edited: Dec 1, 2019
                • Mattax

                  Mattax Just the facts, ma'am FABO Gold Member

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                  Then you'll probably need to make your own circuit diagram. If the new items and the old items are not from the same year and model, terminal positions or connections may not match. Or a terminal may have backed out of a connector.
                  ^^^^This^^^^^^^^^^
                   
                • Mattax

                  Mattax Just the facts, ma'am FABO Gold Member

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                  Schematically, this is all that is needed for the newer ECUs.
                  upload_2019-12-1_10-5-17.png

                  If you're using the original harness with dual ballast, its more like this.
                  upload_2019-12-1_10-46-47.png
                   
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