Headlight Switch Cranks Engine??

Did you have the bulkhead connector apart? Maybe you simply "repinned" it wrongly? What happens if you twist the key to start. I see "round about" you did post that it's a 72 Dart

THIS IS IMPORTANT!!!

I would not start wildly replacing parts. I see no need at this point to say, replace the ignition switch. It is much more likely to be something wrong in the harness


Try operating the dimmer switch and see if the problem changes or goes away. Do any of the lights work properly?
Only headlights work properly.

Dimmier switch I don't think ever worked