Right headlight won't turn on when in Auto mode

[tycksena]

I have a '02 GMC Sierra 2500HD and I'm going to guess this is an electrical problem but my right headlight won't turn on when the headlights turn on in Auto mode. I know the headlight, fuse, etc works because I can manually switch it on using the dome override button or turning it on during the day. The left one works fine when in auto mode. I'm guessing there is a relay or something that controls the headlights but I'm surprised that the left works and not the right. Any help would be much appreciated.

[newdude]

If you use the headlight switch and turn them to on do both work?

[tycksena]

Yes, they both work when I turn them on using the switch. This makes me think it goes through a different relay or something when it's in auto but I don't know. If anyone knows any details on that that would be very helpful.