Date: Wed, 2 Apr 2003 22:07:52 +0200
Reply-To: Robert Steven Fish <fish@SALZBURG.CO.AT>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Robert Steven Fish <fish@SALZBURG.CO.AT>
Subject: Re: idle stabilizer valve question
Content-Type: text/plain; charset="iso-8859-1"
First thing... are you rich?
If so, then buy the parts and try them and see what happens.
If not, then try this... Go through all the major ground wires on the
Vanagon, and be certain that they are sound. Better yet, replace them all
if they are original and show corrosion and/or brittleness. Especially
inportant is the engine block to chassis ground strap on the driver's side.
This one often corrodes, and breaks when the A/C compressor belt is being
tightened, as it sits directly below the A/C.
Then, trade out your existing ISV with a known good used one from a friend.
If this really solves your problem, it can be assumed that your ISV is
either throughouly coated with carbonized filth inside... or just plain
broken. You can try to soak yours in brake cleaner overnight, and then
spraying it, until it runs out clear... sometimes you can clean them, and
they will work again.
If however, the known good ISV does NOT solve the problem (which it probably
won't) then you may have the more common problem, and that is a "fried" Idle
Stabilizer Control Unit. This little black box sits behind your right rear
taillight, and is actually a mini ECU. It is common for a defective or
dirty ISV to cause the voltage regulator to burn out on the ISCU. If yours
is part number 251 907 393 B then there are higher odds that it is fried (as
that is the older model which has a weaker voltage regulator). The newer
one is 251 907 393 D and if you have to get a new one (or a used one) then
get this one, and not the "B" unit.
Anyway... the thing to remember here, is that simply disconnecting your ISV
is not telling you the whole story, as there are other components in the
circuit that you are also cutting out by unplugging the ISV.
Most shops will not replace the ISV alone. They will insist on replacing
the ISCU too.. and on the surface this looks like a nasty trick to get some
extra business... but in actually does make sense. If you have a bad ISV
then chances are high that it burned out the ISCU. If you have a known good
ISCU and a known good ISV, then you can test them both at once... but DO NOT
test a known good ISCU with a questionable ISV, as it can burn the ISCU out.
each of these components can cost well over 200 bucks... so it is advisable
to test things out and find what you really need.
There are also several postings in the archives from about 5 months ago,
when we were discussing this all, and there are a few tips and tricks to
testing and troubleshooting the system there too.
Good luck, and I hope that this helps you get back to normal idle.
RSF
IMPORTANT!!! In order to reply to me, you must have the word "FISH"
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<º)))>{ <º)))>{ <º)))>{ <º)))>{ <º)))>{ <º)))>{
Robert S. Fish
Salzburg, Austria
1987 Wolfsburg Vanagon 2.1 GL Weekender
1987 Golf Cabriolet
1991 Golf
I'm about
> to order a new ISV - mine is looking rusty and old - but wanted to see if
> anyone out there in VW land had any other ideas of things that might be
> wrong to check out first so I don't waste money.
