DRL dosent come on i auto

[H3Sweden]

Hi!
I have a Hummer H3-2006 (earlie). I wounder how the DRL- lights work. On my car I have separate DRL lights in he front witch is integrated with my turning signals. The DRL lamps also works as my parking lights. Now, to my problem. The other day I noticed that the DRL didn't come on i auto mode, the lamps are intact because when i put the light knob in parking mode or headlight mode they come on. I have checked the fuse #39 and it seems ok. The light sensor is ok, if i cover it the headlights comes on. Could it be the relay? Do anyone know the part number of the relay?

Jim