No I do not have a service manual for the 03, but like I find all of my service manuals google search.
My experience with wiring is advanced, with this problem by itself, none. I have never had a relay melt on me before, and having a relay melt that's a serious issue, with as many fail safes these newer vehicles have, for a relay to melt and not trip a fuse first. than go from there.
Experience, wise pretty good since I did a 300zx NA to TT swap and that's one project I hope I never have to do ever again..
But on track, what I said is common sense. if you have a relay melting, than either google search a FSM, or buy one, than grab a meter, and start testing those circuits in question. Its not a 20 minute test either, there are lots of wires and lots of relays, circuits to test.
Simple things are always the best instead of jumping in and throwing money at it. just like if your car doesn't start.. What are the 3 main properties needed in any vehicle to run..
Air, Fuel, Spark. Changing your right rear lug nut wont solve your problem lol