I have 2 questions, what is the small button for that is under the starter button, on the bottom of the dash? 2nd ? Should the starter engage even with the key off and if it shouldn’t, what could be that problem?
Without seeing a picture I'd say dash light dimmer switch for your first question. If you hit the starter button with the key off it will turn the engine over but not start.
Thank you, that’s what I thought, just wanted to be sure. Under the starter button there is a smaller button and a small knob that would seem to be a dimmer.
Ford used the column mounted ignition switch to control ignition and dash instruments only. Everything else had it's own switch, In 1948, they finally changed the ignition switch from the steering lock set up to the dash with a new type switch. Mercury likely followed suit on that but I'm not as familiar with the post war Mercury cars up through 1948. The 49 through 51 Mercs were in the family so I have all the books on them with a few exceptions.