Hey, this could BE the Canadian thing and just cause yer truck is ASSEMBLED in Canada but built for US means it may NOT apply...
We Canuckleheads here in Canada got Daytime Running Lights before US folks did. It's a small module about 4"x4"x1" usually located on LH side of truck in front of rad support behind grill, ..somewhere I can't recall where exactly it's a finned box looks like a small car audio amp
Here I just snapped these images for ya'll
Here is Brick nose, behind grill Low and off to LH side
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Here is OBS and it's again LOW Behind grill and appears to be behind signal lamp...
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That DRLM feeds a lower voltage to HIGH beams when key is on RUN position. This has been an issue with relay mods on more than one Canadian truck. It could be that it is too low a voltage to correctly trigger relay IIRC and subsequently screws with whole light system.
If you remove the DRLM from the equation by disconnecting it, your HB/LB lights will function as plain HB/LB but your dash HB light most likely will not go out.
Hope that this helps out my fellow Canuckleheads
JM2CW today
BTW I've been trying to figure out how to make the DRLM feed to a secondary bulb so not to burn out nice bulbs when I do relay mod removing it from the system so to seak.....
Not sure the above can be done.
E D I T
To add above pictures and locations of DRLM for Brick nose and OBS trucks