Hi,
since you mention 'ign control unit' you might be talking about a 1.9
waterboxer vanagon.

Here's my experience..
can't tell you what electronics are in the Igniter ( ign control unit ) ..
but I can say I don't think I've ever seen a bad one,
and that the white wire, on the far left of the connector plug is 'the wire'
  upon which  the 1.9 ECU 'sees' that the distributor is turning .
  If that wire slips out of the connector plug, and I've seen that
happen, there's no ignition.

Hall sender in the distributor - eventually those fail or get intermittent.
  Bit tricky to replace that part in the distributor. I would get a used
1.9 dist with minimal side shaft play and put a new Hall Sender ( about
$ 100 to 120 ) in it, and keep the old distributor for a spare.

here is a part that can get ya for sure ..
the Idle Stablizer Unit  .....small square plastic box.
It can run with that bypassed, and the plugs are designed to accommodate
that.
I have seen chronic failure to fire up ...
intermittently chronic let's say, and it was that part.
Fortunately they are available new.

more -
I cut that one white wire and put a male-female plug in it,
then I can swap 'stand alone' 1.9 wbxr ignter harnesses in and out, if I
suspect something is wrong with one.

if you have a 2.1 waterboxer,
  I would have written something else instead of the above.

it's a good thing vanagon people posting on lists are not pilots ..
if they were they'd be killing people left and right with their unclear
communications.

it's all fun though.
scott

On 6/17/2012 11:37 AM, tinker man wrote:
> Just wondering - what electronics do the hall sender and the ignition
> control unit contain?
> I want this info to be better able to diagnose these if necessary
> before I go shopping in case van starting problems, these parts ain't
> cheap!
> Has anyone dismantled them and has posted pictures somewhere or can email them?
> Tnx.
>