I've already checked the ground by measuring the resistance at the bulb check unit socket to battery ground for each stop lamp wire (bulb unit out-open circuit). In both cases, the resistance was solidly one ohm with the bulbs in place and infinity with the bulbs removed.

Since the current for the stop lamps flows through the brake switch to the bulb check unit on it's way to both bulbs, a bad spot on the switch adding a llttle resistance could lower the current and trip the bulb check light. It would look like a poor ground or bad connection. At least that's still my theory. I'm going to pull the switch and check.

Thanks for the comments.

Brent Smith