I own a 2001 f350 with a 7.3 diesel. On this year of truck, when you turn the key to let the glow plugs warm up, the daytime running lights come on. I think this is unnecessary wear on the batteries. Is there any way to unhook the daytime lights so that the lights only come on when I turn the switch? Thanks for any help.

Have you tried putting the park brake on?
Usually it will open the circuit to the module.