I had a "Gucci" German brand car once with OBD II and a very similar
engineering set up(Bosch) as Vanagon, but maybe 20 times as complex.   It
would illuminate a Check Engine Light (The verbage in the dash was in
German, I think) if I dared to change my light bulbs with another that
didn't match exactly.   I found that Volume 2 of 5 on the electrical
systems said I should have my dealer be certain to change the lightbulbs in
pairs..because the diagnostic system would detect any difference in voltage
draw.  This was indeed the case...Put in an Autozone or O'Reily's bulb and
that P-car said "Nein! Verbooten!" every time.
    That might be somewhat the case for  the vanagon, too.    I think
somewhere in our books it mentions that a 'fast blink' is an indication
that all is not well with that lighting circuit...I could be imagining
reading that...

      I was given an equipment violation citation in Kalifornia for one of
my tail lights being "dimmer than the other".  The CHP had a very sensitive
Eye......   I've begun swapping both bulbs when one fails...I keep the
second, the  still-lighting one, as an emergency spare or put it in my
trucks....
      I've also encountered the "fast blink syndrome" when connected to a
towed unit with a faulty ground ..  Cleaning grounds and making certain the
sockets and bulbs are making good contact, that often will fix the fast
blink.
   Don Hanson

On Jun 27, 2014, at 2:48 PM, JRodgers <jrodgers113@GMAIL.COM> wrote:

Just replaced fractured and water filled front turn signal fixtures with
known working good ones from Ol'Red - my 88 GL which is grounded for a
while. I also replaced the missing turn signal/flasher relay with the
one out of Ol' Red. A new relay arrived today in the mail.

Once it was all put together - I tested the turn signals.

The right hand signals - front and rear work nicely -
Click----Click----Click----Cli
>
> ck!
>
> The left hand turn signals also work - but  not so nicely -
> ClickClickClickClick.
>