Date: Sun, 21 Feb 2010 19:19:20 -0500
Reply-To: mordo <helmut.blong@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: mordo <helmut.blong@GMAIL.COM>
Subject: Re: ISC troubleshooting
In-Reply-To: <vanagon%2010022118223572@GERRY.VANAGON.COM>
Content-Type: text/plain; charset=ISO-8859-1
That's good info. In my case, the unit simply ceased to function. It was
likely a result of an enthusiastic powerwashing event.
While it is challenging to the eyes to inspect all of those resistors,
capacitors and transistors, there are no obviously burnt components. I think
it's unlikely that water ever got anywhere near the circuit boards so
perhaps it was a purely coincidental failure.
I had hoped that there was some experience with testing impedance and
continuity of the various circuits within the unit so as to narrow down the
components most likely to have failed. It's an expensive part and it would
be nice to think that it could be serviced instead of being replaced.
cheers,
On Sun, Feb 21, 2010 at 6:13 PM, Ed McLean <email99@bellsouth.net> wrote:
> I may be able to help here.
>
> I had the racing idle problem in 1997 in my '86 Westy. I finally traced it
> down to excessive heat from a transistor in the idle control unit (ICU). I
> found the unit would work OK if the ICU circuit boards were removed from
> the
> plastic case, allowing greater cooling. The fix in the archives was to
> replace the discolored transistor with a higher power transistor with a
> heat
> sink that would handle the current without generating too much heat. This
> worked for a while until the idle began to fail again. I found drilling a
> hole in the ICU case and sticking an even larger heat sink for the
> transistor out of the hole for greater cooling worked until I removed the
> engine for a conversion. The components in the ICU were not burning out
> initially but something was becoming erratic because of the heat. I think
> the primary problem was the idle control solenoid began drawing too much
> current causing the current switching transistor to overheat. The heat
> inside the ICU caused the secondary problem of the shutting down the
> control
> circuit, resulting in the engine racing at idle.
>
> I can provide pictures if anyone would like to see.
>
> The first time this happened was in a parking deck. The Westy had an
> automatic transmission at the time and I had a broken arm in a cast. It
> was
> real scary.
>
> Ed
>
--
mordo
1990 Carat
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