Good morning, Dennis. It sounds like you may be onto something. I've changed from incandescent to LED on some of our clearance lights and most all of our interior lights, but not our turn signal "bulbs". I do know that many have had issues with converting those, I think mostly to do with conventional thermal-type flasher devices. Also, while an ohm-meter can be a great tool for testing the existence of and possible operability of an LED device, the actual ohm values are not terribly useful, other than that there should be a very high resistance in one direction, perhaps "infinite", and a far lower value in the other direction.
You might try the grounding idea and see what you get. The 2 amp value seems a bit on the high side for a 12 volt device, particularly an LED device, as that would be 24 watts. I would think that to be quite a bit for an LED lamp, by itself.
But I really do think you are on the right track. We are like you. The fun-factor in driving these beauties is, in my opinion, severely reduced when doing it at night. I just found out that my headlight switch is bad a couple of weeks ago while ferrying our coach to a repair facility before sunrise. We just never use them, so didn't know I had the problem. New switch is now "in hand", so I'll be good to go.
Jim & Angie, Boise, ID
2006 Monaco Dynasty Countess III
2017 GMC Acadia Denali