Trailer wiring question - identify pins?

[wpoll]

Quick question - I am about to remove some after-market trailer connection wiring and restore the "factory" loom as it has been cut up by a P.O.

Trailer lights all work fine but the CC announces "Check Trailer Lights" whenever a trailer is attached. I know why - and how to fix it but before I rip everything apart to restore the "factory" connections, I want to be sure about what the P.O.s modifications are doing.

On connector X393S, both pins 2 (GERT - Yellow and Red) and 5 (GRRT - Slate and Red) have been replaced by a high capacity +12v conductor wired to the battery positive via a large fused relay. This relay seems to be connected to the LCM up front (there's a single wire running to front of car) and to X393S pin 6 (SWWS - Black and White).

My question is; What signals are on X393S Pins 2, 5 and 6? I'm thinking the X393S pin 2 is the brake light circuit, and the others must something like reverse light and control. I guess I can stick a meter in each pin and watch for voltage jumps but if someone can decipher the pin outs for the TCM or connector X393S for me, I'd be very grateful!

FWIW, X393S pin 2 is labelled "55A", pin 5 is labelled "58AR" and pin 6 is labelled "53A". I have the E53 "hitch" PDF too but it doesn't tell me the circuit use - just everything else!

Thanks in advance.