That box is just a mileage counter.  On your '84, it turns on your OXY
light after 60,000 miles and again 60,000 miles after each reset.  It's
to "Remind" you that you should test/change your oxygen sensor.  It
doesn't perform any "Useful" function.  In fact, VW eventually got rid
of the box as the latest Vanagon models don't even have them ... hence
the availability of the full length cables.

I've even thought of using the OXY LIGHT to do something different like
indicate when the fridge is on 12 volts or something (my Westy has an
aux battery and the fridge will run on 12v even if the engine isn't
running).  Or indicate when the brake lights are on ... or anything
besides saying, "Hey ... you've gone another 60k".

Mike
'84 GL 7 pass
'85 GL Westy

Bob Mac wrote:
>  The small cable from the box to the wheel hub broke a few weeks ago on
> my 84 vanagon. I ordered a cable from B-D and it's on backorder for
> weeks now. My question is what purpose does this box serve. I can buy a
> full length cable and eliminate the box. Or is this not a good idea.
>