'06 GMC W5500 wiring issues

[RickyDL77]

ok, I'm usually only working on small engines but i know a little more than the others when it comes to electrical issues so i was nominated to try and solve this problem.

The problem lies in the headlight / running lights. we have 6 of these in service and 2 of them keep having reaccuring problems. The one i am working on now is all mucked up...it just had the stearing column controls replaced about a month ago. Afterwards it seemed to be doing ok.

With ignition off:
running light switch on....nothing
headlights turned on.... headlights are on but default to highbeam.. switch the highbeam and the relay starts buzzing.....running lights never turn on, neither do the dash lights.

With ignition on/not running:
all the same as before

Igniton on/engine running:
headlight switch off.....headlights on
running light switch on....headlights still on, no running lights, highbeam light is on but with low beams
headlight switch on.... headlights on, no highbeam light but highbeam is on, no running lights...engage highbeam causes low beams on and starts the buzzing of the relay for headlights.

Headlights are new.. HB5 9007 both sides, thinking maybe these are not the right bulbs? Is there a daytime running light module under the dash somewhere, and if so how to test it.. and any info on where to find a service manual or wiring diagram for this thing would be great.

Was thinking maybe the NPR Izusu would be the same as for the cab wiring since this is an izusu cab, the title calls it a NRR model.

Please any info about this POS would be great thanks.