Joseph Meehan wrote:
>
> Darren Dunham wrote:
> > I took my 2003 Passat in for "engine light" service a few weeks ago.
> > They apparantly replaced one of the ignition coils. Ran great until
> > this past week.
> >
> > Then not only did it suddenly develop bouts of "sluggishness" (poor
> > accelleration, rougher idle), the cruise control doesn't work.
> >
> > While I wait for the service appointment, does this sound like
> > anything in particular? I was a bit surprised that they both went
> > out at about the same time.
>
> Some cruse controls are vacuum controlled. A loss of vacuum could cause
> both problems.

The Passat could be different, but on my '87 GTi the cruise is vacuum
operated, but it has its own vacuum pump and does not use engine vacuum.

As I understand it, the cruise control function on newer VWs (with
throttle by wire) is built into the ECU firmware. I would imagine that
if the ECU detects something wrong, it could automatically cancel the
cruise.