@Mike: No, it's not the driving lights. The Daytime Running Lights (DRL) is a feature that turns on the headlights at a lower power during the daytime. It only turns on headlights, not marker lamps. It usually only turns them on when the vehicle is running, in gear, and the parking brake is released - although configurations may vary from one manufacturer to another. As I understand it, DRL is required in Canada, and possibly in some states in the US. I have been exploring the issue and find that it was/is an option on Monaco coaches, and I suspect it was on ours as well. On some Monaco coaches, owners have been able to add a module made by a company called Hamsar that turns on the DRL on their coaches.
My coach has an empty socket for a DRL module or relay on the extreme left side of the lower row of relays on the circuit board in the chassis electrical service bay. I may be barking up the wrong tree here, but I am beginning to suspect that the option was not installed on my coach and that may be why my ICC lights don't function properly. I'll post a photo of the circuit board later to try to explain.
I know I should just leave well enough alone, but my OCD won't allow it...