[kevan]

I've tried a number of ways to circumvent the auto headlight "feature"; none work reliably. Also, the wiring diagrams supplied by Helm in their service manuals do not show this series of circuits.
Pulling the fuse &/or relay for the DRL's does nothing about the auto function. Unplugging the dash sensor doesn't work either, as the lights come on as soon as the parking brake is released, regardless of how much light there is.
I tried illuminating the sensor with everything from a flashlight to a very bright 4300K LED in a small light tube; no joy there at all.

One way to keep the lights off might be to bypass the dash sensor. I'm thinking it must deliver a certain voltage to the timer when the light level is high enough to leave the headlights off, and probably reduces or eliminates that signal when it gets dark. If that's so, the easiest way to prevent the lights from coming on might be to emulate whatever signal the sensor sends out.

Anyone have any thoughts on that?