James,

  PLEASE TELL US WHAT FIXED your van!!!
  As to the control unit, the only way I can think of testing it
is to find someone with the same year vanagon, then switch the units
[they plug in and are held in place with 2 sheet metal screws]
to see which van runs properly.

  Is there anyone reading this in Pittsburgh with an 85 vanagon
who would be willing to spend 15 minutes letting me try this?
[switching them back of coutrse]

  Bill