'94 100CSQA Multi-function Switch?

[mwvogt at mindspring.com]

Friends,
All of a sudden...no back-up lights. I'm told it could be the multifunction switch on my '94 100CSQ Avant. Never knew these even existed or if any of my other Audi's have them. Told it is mounted on the left side of the autobox. 
Anybody had any similar experience or could shed some light on this switch and what it's multifunctions are, before I open an electrical pandoras box.
TIA
Mark Vogt
Exeter, NH

'94 100CSQA
'90 80
'87 5KSA
'84 CGT 5E