[V8] back-up switch wiring diagram

[Kent McLean]

I'm trying to decipher the Greek (sorry, Pantelos) that is the Bentley V8 wiring
diagram.

Back-up light switch, p. 45:
<http://home.comcast.net/~kentmclean/audi/v8/backup_lights/45_backup_light_switch.jpg>

Back-up light relay, p. 47:
<http://home.comcast.net/~kentmclean/audi/v8/backup_lights/47_backup_light_relay.jpg>

P. 45 nicely shows the back-up light switch. I can see a brown wire goes
to ground (Note 102, in the transmission harness) and a brown/black wire
goes to the Automatic Transmission Control Unit (ATCU). My guess is that
the ground follows the other wire up to the ATCU.

P. 47 confuses me.  I can see the wiring from ground to the lights, then to
the relay (black/violet).  From the relay, a black/blue wire goes to box "318",
and a blue/red wire heads for the ATCU before veering left to (no-box) "x1".

Questions:
Is 318 a connection box on another wiring diagram page?
Is x1 also a pointer to a link on another page?

I would expect those wires to end in the ATCU, so the back-up light switch
can power the back-up light relay. I can power to the relay from a blue wire
in the ATCU and cause the back-up lights to come on.

All I need to do is connect the back-up light switch to the relay wires I
found in the ATCU. I'd like to find wires in the existing harness, rather
than cobble something together. (And I still haven't found the switch on
the transmission; I'll have to jack it up to feel for it.)

-- 
Kent McLean
1999 A4 Avant, V6 Tiptronic
1991 200 TQA #3, with mods
1990 V8 w/5-speed and other mods
gone: '91 200 TQA x2, '94 100 S Avant, '89 200 TQ "Bad Puppy"