In both the owners manual for my Syncro Westie and the Bentley,
     pictures of the diff lock controls show a single push-pull switch
     mounted below a diagram of the chassis/powertrain, front wheels to the
     left, with a single green indicator light between the two rear wheels.

     Pull the switch out, the rear diff locks and the light goes on, natch.
     Indeed, this actually happens on my van, like it is supposed to!

     However, on my van, there are also two more little lights (or places
     for lights, in my van they don't light up) indicating the center and
     front differentials. I can't find these lights in the Bentley wiring
     diagram, nor pictured anywhere else.

     I deduce three possible explanations: (1) front and center diff
     locking were an option, undocumented in the manuals, that I don't
     have, and if I did there should be three seperate push-pull switches?
     (there are places for two more to the left of the first).

     Alternatively, the one switch should operate all installed diff locks,
     and either (2) only one of my lights/diff locks is working and I have
     a problem, or (3) I only have the one diff lock, and the additional
     light positions I see are dummy positions for additional diff locks if
     they are installed.  Can anyone help make sense of this?

     If this is horribly confusing or boring, I offer a mini-trip report:

     Saturday I took the Syncro Westie to the Range Rover Test Area, on an
     abandoned farm located in the DC area (The importers US headquarters
     are located nearby). This is not a publicized area, but there are no
     gates, though they have used bulldozers to build some small berms
     across the entrance road which filters out Toyota Camrys and the like.

     We let the Goodrich AT tires down to 20PSI (I use 40 on the hi-way),
     got green-to-go on the diff lock, slipped it into the granny gear, and
     lumbered over the berm. The whole area is about 100 rolling acres,
     criss-crossed with trails that climb up and down through open, scrubby
     areas and some woods. Many of the trails were heavily rutted, with
     high centers that could easily catch the bus. It was very dry -drought
     back here lately- the soil is clay, and I could imagine that after a
     heavy rain, this place would be a total mess. We bounded (well, twice
     we got into second gear) over hill and dale, dodging ruts, tree limbs,
     and dirt bikes. I am certain that this is a good place to learn
     the limits of vehicles and drivers.

     One thing we did not try was called "The Pyramid" by my six year old
     son. This was a small hill sort of thing constructed of railroad ties
     and clay soil, climbing at about a 40% angle, so you could practice
     driving up and down stairs.

     After about two hours of horsing around, more and more dirt bikes
     appeared, and we began to worry about the numerous blind corners and
     hilltops. We picked a large bouquet of wildflowers (where do you mount
     blumenvasen in Vanagons?), crawled back over the berm, pumped up the
     tires and headed home.

     Tom F.
     1990 Syncro Westie
     1900 Audi 200 Turbo Quattro Wagon IA Stage I