[RABarrett]

I hate to be the bearer of bad tidings, but it sounds to me like a head gasket is the issue here. These vehicles had a problem with head gaskets anyway, and when the problem occurs, it typically allows compression pressure into the system, creating circulation problems in the cooling system. Likely, the coolant was lost very slowly, with no apparent loss from the bottle. Though I am not sure, I do not think the headlamps use a relay. It is likely a switch problem, or other connection. Ray