If anything is grounded to the chassis, and he said the lights are, this floating ground buss bar, must also have a connection to the chassis someplace, or no lights. This is the best in our situations, and most complex(?) solution, and a bad ground is a lot easier to trouble shoot, and all grounds are very close to the same resistance.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
