Date: Wed, 1 Nov 2006 13:25:02 -0600
Reply-To: Jim Felder <felder@KNOLOGY.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Jim Felder <felder@KNOLOGY.NET>
Subject: Re: Cruise control diagnosis progress - ambient temp?
In-Reply-To: <004701c6fde8$1871a9a0$657ba8c0@MAIN>
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Do you have any ground problems that you know of? You could have
temperature sensitive sensor or controller problems under the dash.
Read on for my two cents.
I took my vacuum control unit completely apart to understand how it
works. It's fine and back together. The problem is up front in the
electricals.
To begin your own diagnosis, pull the tube off the vacuum pump in the
back and pull a vacuum in it. You should see the rubber bellows
collapse and stay that way, advancing the throttle.
Bend over the rubber hose and wait. The vacuumm should hold. This
just takes a minute and will tell you a lot about the overall ability
of your system to hold a vacuum. Try this on a day when your CC is
working and again on a day it is not working. If there's no
difference, then the problem isn't vacuum related.
Now go to the front and lay a piece of two by four with other weight
as needed to open the clutch vacuum valve. Now go to the back and try
to pull a vacuum again. You should not be able to. Now go to the
front and put the weight on the brake pedal. Again, you shouldn't be
able to pull a vacuum.
Now test the vacuum unit by removing the three screws and the plug in
the bottom. There are three prongs on the bottom. Two of them stand
opposite each other. Twelve volts applied to them will run the motor,
but will not pull a vacuum. To do that, the vacuum-breaker operated
by the internal relay must be checked operational. Since it's so hard
to do all these things at once, do them one at a time.
First, move the positive 12v clip from its motor operating terminal
to the one standing sideways to the two opposing ones, the one in the
middle of the three. You should hear a click. That shows that the
relay is operating.
Now take a knife blade and pop the top off the oval casing, you'll
see the separation line about 1/8 inch down from the top edge. It
comes off easily. Switch the test leads back to the motor running
position. With the motor operational, manually depress the top of the
relay. Voila, vacuum. The relay, the vacuum breaker operated by the
relay, and the motor and reed valve assembly (not for the faint of
heart, must be dremeled apart and welded back together with a
soldering iron, but you probably don't need to do this) must operate
to have vacuum.
If all these vacuum operated components are working, it's time to
look under the dash. Look in Bentley at 27.29 for troubleshooting
what comes next, which is as far as I've had time to get to. That's
where all the electrical stuff is, which is just as likely--if not
more so--to have temperature-sensitive continuity issues.
Jim
On Nov 1, 2006, at 1:01 PM, Robert Fisher wrote:
> I'll throw a guess out there... you have a slight vacuum or
> diaphragm leak
> in the system that becomes a significant leak when cold
> (contraction of the
> rubber) and becomes a negligible leak when warm (expansion of the
> rubber).
>
> Cya,
> Robert
>
> ----- Original Message -----
> From: "Anthony Egeln" <regnsuzanne@YAHOO.COM>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Wednesday, November 01, 2006 7:48 AM
> Subject: Re: Cruise control diagnosis progress - ambient temp?
>
>
>> I don't know if this will be helpful or not....but did it work
>> when the
>> weather was warmer? I have the stock cruise control in my '89
>> Syncro GL,
>> and whenever it gets cold it doesn't work (which means here in
>> northeast
>> Florida anytime it gets below 60 F....ok, ok, all you people in
>> the great
>> white north can stop laughing now!). In fact, I never knew it
>> worked until
>> I moved to Florida, because it didn't work at all in the north.
>> Works like
>> a champ here (above 60F).
>> What could it be about cooler temperatures that makes it inop?
>> Anthony
>> '89 Syncro GL (Hidalgo)
>>
>>
>> Jim Felder <felder@KNOLOGY.NET> wrote: Bellows good.
>> Pedal switches good.
>>
>> Removed vacuum pump and put 12V to it. It runs noisily, but doesn't
>> seem to pull any discernible vacuum.
>>
>> Should it pull enough to hear a smack when a finger is removed from
>> the vacuum side? Mine is too weak for that.
>>
>> Jim
>>
>>
>>
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>
