OK, Age is catching up with me.
... when the incandesents are replaced with equiv Leds....simple resistance measurements don't work anymore...I think. Am I not seeing the forest for the trees??
Nope. You're right. Simple resistance measurements won't
Apply 12VDC and see what lights up
Best to run a meter between each proposed pair to make sure nothing's shorted, first. Maybe put a low-amperage circuit breaker in line with your test leads?