Headlight circuit diagram

I am trying to troubleshoot the head lamps on a 1997 International dump truck model 9400 that a friend of mine bought but I know nothing about the interface (how the day time running lights work in tandem with the HI/LOW beams).
Being a low voltage alarm technician, a circuit diagram of this particular subsystem would be a real find. I would rather ask for that than describing the problems that this friend is experiencing.
Is there anyone that could provide me such information, or a place to find this?
Thanks in advance,
--
Sergio

 

Nevermind the initial question, I'll have some local guy here explain me how the daytime running lights interface with the high beams and how the dashlight Hi-beam indicator should be operating. These modes right now are really making all these components (the head lamps and the hi-beam indicator) look more like a light show than an informative feature. Why make things simple when they can be complicated? When I'll find out how all these components operate, I'll make sure to post back a dilligent reply.