Don't feel dumb. It took me an hour and a half bottle of aspirin to come up with that response! Quite challenging these new style schematics.
Pages 40-23 thru 40-26 pictures five of the six relays mounted in the fusebox along with their designation number - either "I" or "N". The top row, left to right, are I3, empty, 'missing', I12, N25 and empty. The missing one is your relay #3. I then looked at pages 40-18 & 19 to see what all the I & N designations are. 37 of 'em!! Won't find it that way! I then looked at one of the fusebox schematics and noted that the relay sockets, labled from bottom to top, are I3, blank, 'N10', I12, N25 and empty. Wow! Same order as in the picture. Device N10 is the roof lamp timer. Simple. Yeah, right!
Just hope it's the right answer.