70 Duster ignition problem

[41husk]

My 70 duster was running fine.  Had her out for about 20 mile drive. returned home and out her in the garage.  The next day she starts but dies when you let go of the key.  If you hold the key in the on position she will continue to run until you let go of the key.  I have changed the ballast resistor, starter relay, ignition switch and key tumbler.  After every item the problem persisted   Please help!!!!!

[Bronzedodge]

Well, I'd start be turning the key to the "on" position without starting it and see if you have voltage at the coil primary.  a 70 Duster would have had points originally, is it a Mopar Electronic conversion?  Bad ground to the box maybe?

[Staxbro]

When in the start position, all the ignition power goes through the brown wire, bypasses the ballast resistor and feeds the coil + "full juice" for startup power. When you release the key, ignition power runs through the dark blue/white tracer wire to the other side of the ballast resistor where the "low juice" power feeds the coil + for constant running. If all runs well, in the start position, I would first try another ballast resistor. They are known to be unreliable, and no guarantee a new one is ok.
After that, I'd check the dark blue wire with tracer circuit for continuity, resistance and voltage drop. Renew if at all suspect.

It was a problem like this that started my dash rewire....😰

[Nacho-RT74]

I was pretty sure already replied about this!

Have you got the brake light on cluster with key in RUN ?

If not, can be the ign switch or plug ( can recall if the RUN circuit to underdash harness got a fuse on A bodies like B got )

If you got, have you got power at ballast on blue wire ?

If not, can be the engine harness plug at bulkhead, bulkhead itself or any other plug allong the engine harness carrying the blue wire.

If you get the brake light at cluster dimming while cranking, then the engine harness, ballast and bulkhead are fine