Hello again Søren,

Here is another email for you; this time from my friend Steve.

Good luck!

Regards,

- Jeremy

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On every Audi other than the V8 I've been able to fix the CC with simple measures ... adjusting the pedal switches or repairing vacuum leaks ...
that's still the first place to start in my opinion. You only have one switch on the automatic ... on the brake pedal. Make sure that the switch protrudes enough so that the pad that senses the pedal is fully depressed against the switch body when the pedal is released.

I've seen problems with integrity of the vacuum system that drives the actuator. If you pull the vacuum line from the pump and apply a vacuum there you should observe the throttle actuator motor get pulled in. If you don't have a vacuum pump you can depress the actuator motor and then pinch off the end that attaches to the pump and the actuator should remain in position when released. If you do not find this to be the case ... check to see that the pedal switch isn't leaking (in my experience a sign of a need for
adjustment) or look for a broken "T" fitting in the system near the CC actuator. Of course, check that the linkage rod is attached to the throttle body linkage while you are doing this. Unfortunately most of this stuff is buried behind the engine on the left side.

There is another bizarre possibility which you may want to investigate ...
the CC uses the "hot" side of the brake light circuit to get its ground. It is a fail safe measure, that way when the brake lights come on the CC is guaranteed to lose its ground. If you lose all your brake lights the CC will stop working too ... check to make sure that the brake lights are functional.

One other peculiarity of the automatics is that the CC power is enabled by the tranny computer, so if you have any tranny codes it may disable the CC ... read out tranny codes and get them cleared.

Now ... to what I found on my car ... None of the simple stuff solved it so I followed the troubleshooting guide in the book. I found the ON/OFF switch was bad ... I replaced it and the car now has CC. Given your situation, if you suspect that the problem is due to a bad switch or the tranny ECU you might want to install a temporary fix by supplying a direct switched power connection to the Cruise Control system. I do not think there is a big risk to doing this ... I drive around with the CC on most all of the time anyway ... If you want help in figuring this out get back to me and I'll get the wiring diagram out and figure something out ...

I've never had a situation where the vacuum actuator, vacuum pump or CC controller has been the cause of a failure ...

I hope you have a very safe trip out and back ...

Steve Buchholz
San Jose,

1990 V8Q Zyclam Portland, Oregon (USA) http://www.MyV8Q.com/ Fun, Fun, Fun auf der Autobahn