I went out today to take a look at that 3rd relay, and unfortunately those 3 relays are all for the fans.To my surprise though, while I was fiddling in that area, I found another relay hanging loose that I assume had come off the crossmember and was tucked away where I couldn't see it underneath the battery area. Nowhere, in any of the manuals & documentation I've found, is this relay mentioned at all and if I hadn't been pulling on the loom for more slack I would never have known it was there. I checked the colour coding of the wires, and it matched the wiring I expected for the TC Relay. This relay is the same type as the other 3 for the fans, so I swapped one of those over with the TC Relay, giving all the contacts a good clean in the process. I cleared all the codes with a borrowed ODBII tool, and I'm back to all 4 gears again. I've done around 20 miles and made sure all 4 gears are kicking in so I'm happy that my problem's solved. Thought I'd post this up here in case it helps any others with the same problem.
