Well, the end result to this brake problem was to disable the factory unit, and install a new Tekonsha Prodigy P-3. Neither the GM dealer nor the trailer dealer could find the source of the problem, since it was so intermittent. The P-3 comes with some really great reviews, so decided that was the best option to go with. We shall see. So far, so good. Road trip coming up soon. I liked the ITBC, but it was becoming very unreliable, hence the choice to go with the aftermarket one with a fairly proven track record.