Ignition won't crank engine unless ballast is unkooked

Hey trying to find out if anyone can help me with my 74 360 4speed duster started up fine yesterday on the key now will not turn over on key unless I unhook one side of ballast tried crossing over at starter relay with key ignition on ballast hooked up and then still will not start until I hot wire from coil to battery any ideas what this could be I have replaced my starter/ignition relay and my ecm and has new ballast

It sounds like you have a bad ballast resistor. You said you replaced the ballast but was that before this all happened or after as you were trying to figure it out?

did you mess with anything else, or what were you doing before it stopped working?

is there zero power, no starter movement? or is the starter cranking but car is not firing

Hp74dusterman said:

Hey trying to find out if anyone can help me with my 74 360 4speed duster started up fine yesterday on the key now will not turn over on key unless I unhook one side of ballast tried crossing over at starter relay with key ignition on ballast hooked up and then still will not start until I hot wire from coil to battery any ideas what this could be I have replaced my starter/ignition relay and my ecm and has new ballast

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I'd help you but you need to type out your question using sentences and punctuation so I can understand you

Let's start with terminology:

Crank: This means the engine rotates when the starter works
"Turn over: Means same as above

"Fire" This means coughs, tries to start, may run for a second or two or keep running

"Runs" Obvious. Engine fires (starts) and runs, but may not be smooth or correctly

So first, does the engine crank or turn over? I cannot imagine a ballast problem that will affect the engine cranking unless someone has hacked the wiring


74 has the DREADED "Seat belt interlock." This is a box, under the hood, on the fender apron, with an originally red reset button out the top. If you trip this due to seat belt problems the car will not crank with the key. To "fix" it permanent, pull the connector and find the two yellowish wires and splice them permanently together. These yellows are interrupted by the box tripping, and the yellows are your "start" wire on the way to the starter relay

Nothing at the ballast should affect or be affected by the engine cranking

Now regardless of the cranking (or not) problem, turn the key to "run" and put a light or meter on the coil+ and ground. You should get maybe 6-8V or so, not 12, and not "nothing." This 6-8V or so shows that the coil is getting power and that the coil is drawing current through the ECU which it should

The ECU by the way MUST have a good clean ground

If it will not fire with this voltage present, and by jumping the start relay, post back with what it does "or not"

I'm with 67Dart273. Your "will not turn over on key" means the starter is unable to rotate the engine. Is that what happens, or do you mean something totally different? If true, that problem is unrelated to the ignition system (spark), other than that they share the same source (blue IGN wire). When the key is in the "crank" position even that link disappears since the coil then switches its source to the IGN2 wire (thick brown).

My brother's Duster did something similar where you turned the key but it wouldn't crank when it was working fine the day before. Wiggled the connector coming off the steering column and it cranked fine. I think it was the yellow start wire on the end of that connector that wasn't getting a good connection.

Hp74dusterman said:

...74 360 4speed duster...

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Real 360 Duster or Duster with a 360 swapped into it? Original 4 speed car?

Something else to think about is the clutch switch. It's what supplies the ground for the starter relay to power the starter solenoid. On the factory cars (that haven't been modified), you have to have the clutch in to start the car.