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Audi A4 1996-2001, S4 2000-2002 (B5) A4 cruise control circuit diagram please


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Last Post: Apr 29, 2008 6:21 AM Last Post By: AlecBryant
fast928

Posts: 4,192
Registered: 03/01/02
Re: A4 cruise control circuit diagram please
Posted: Jun 23, 2006 6:27 PM   in response to: Fixit in response to: Fixit
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You're allowed to disagree but I've seen this in actual practice rather than reading a paragraph in a manual.

Checking the cruise is actually a method I use to determine the failure when a speedometer stops working.

If the speedometer quits it doesn't necessarily mean the VSS failed (i.e. if the VSS signal is good your cruise will often still work). However, if the VSS fails the speedometer will quit working; as well as your cruise.

When you deal with Audi models that have a tendency to have internal speedometer failures AND VSS failures; the above information goes a long way in quickly diagnosing the problem.
Fixit

Posts: 866
Registered: 08/31/04
Re: A4 cruise control circuit diagram please
Posted: Jun 24, 2006 2:42 AM   in response to: fast928 in response to: fast928
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Thanks Fast - I see your point. But let's face it the CC is a pain when it gives trouble.
fast928

Posts: 4,192
Registered: 03/01/02
Re: A4 cruise control circuit diagram please
Posted: Jun 24, 2006 8:29 AM   in response to: Fixit in response to: Fixit
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Can be! The most common failures are:

1) Vacuum leaks/Vent switch
2) Stalk switch
3) Vacuum pump
4) Control module

..in that order.
kermac

Posts: 15
Registered: 03/16/06
Re: A4 cruise control circuit diagram please
Posted: Dec 3, 2007 3:01 AM   in response to: Fixit in response to: Fixit
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Sorry Fast - I've never disagreed with you before.
But here is an extract from the Bentley manual:

"The speed signal (necessary for cruise control
operation) can be suppressed by malfunctions in other
systems; for additional information, see index for
speed signal checking procedure."

The speedo will still work because the signal goes
there first then to the other components that make
use of it.


(Posted by Fixit on 22 September 2006)

Hi Fixit

Just found this post of yours, and don't know if you are still wired into the Bentley forums?

Your advice above to "see index for speed signal checking procedure" is a bit of a mystery. I can't find any such reference in the index of my Bentley manual, indeed the index is not generally so detailed as to make references like this.

I have checked all references I can find to the G22 speed sensor, the speedometer, cruise control and all related functions - niente!

I came across a reference - I believe it was on one of these forums, can't remember where - but I'm pretty sure it wasn't quoting Bentley, and I'm equally sure it was a guide on how to check that the Hall effect speed sensor was picking up a signal from the plastic ring inside the transmission case (you should get four impulses from each revolution of the front left wheel).

The guide I'm thinking of also made no reference to malfunctions on other systems, nor to the quality of the signal received at the speedo.

Anything you are able to add to this topic?

Thanks

kermac
AlecBryant

Posts: 2
Registered: 04/25/08
Re: A4 cruise control circuit diagram please
Posted: Apr 29, 2008 6:21 AM   in response to: kermac in response to: kermac
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Complete diagnostic procedures are found at: http://forums.audiworld.com/a4/msgs/1273770.phtml However the 12V tests of the CCM pins are not accurate since 12 V to pin 11 goes through brake light switch and CC brake switch. I tried cleaning the CC switch with alcohol which did not work so I LIGHTLY sanded the copper circuits with 2000 grit sandpaper then cleaned with alcohol. Working fine now. Remember that if you leave battery disconnected long you will have to adapt TPS and Kickdown with VAGCom to get the transmission back to normal

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