Fuse #38 is for the Subwoofer(which didnt come with my truck). My truck came with a 25 amp fuse in the #38 slot. This leads me to believe that I have some part of that wiring in my truck. I also noted that I do not have a fuse for #114 , heated power mirror, which I dont have.
Ya think I have part of the harness in there?

 

I have a 2003 screw and was wondering the same thing. If as i understand it they use the same harness for all the 150's. I was thinking that if this is true i would also like to add a set of extending ( for towing) mirrors with the heated feature. I do kuno that the harness is there for daytime running lights all they left off was the relays. what else is there that we don't know about?