Tiptronic engagement issue

[scottmgibb]

Hi there,

I am having a problem diagnosing an issue with the automatic gearbox on my 2002 S8 D2. I have had the car for around 3½ years, and have lived with this issue throughout. The problem is that the gearbox will not (generally) allow the engagement of Tiptronic mode. The scenario is this:

Gear display on dashboard goes into ‘red’ error mode as soon as you start the car and stays that way permanently.

Car drives perfectly normal in D, R & S modes, but moving the gear leaver into Tiptronic position does nothing.

However, if you are very quick to move the leaver into the Tiptronic position when starting the car then it does go into manual mode, and the gear display on dashboard shows the normal 1-2-3-4-5. It works perfectly in manual mode (both using the leaver or buttons on steering wheel).

Putting it back into ‘D’ mode does nothing (you can move it back and forth between D and Tiptronic modes and it just stays in Tiptronic), but if you put it in R, N or S mode it will revert back to the dashboard ‘red’ error mode, and then will then not go back into Tiptronic mode (though D, R & S modes continues to work perfectly; D works again once you have been in one of the other modes).

The VAG-COM error is shown is:

18152 – Tiptronic Recognition Switch (F189): Short to Ground P1744 – 35-00 - -

If you try clearing the code it just come back up straight away.

I have tried swapping over the F189 switch for another one out of a used gear lever from Prestige, but this gives the same results (with the code clearing/reappearing being the same too). Of course this used switch could have the same fault, but it was in theory tested before being sold.

The fact that you can engage (albeit in a very specific way) the Tiptronic mode and manually change the gears would seem to suggest that it is not the F189 switch that is at fault (though the fact that is does not switch out of Tiptronic mode when moving back to D is odd).

My other thought is the F125 switch, but the fact that both automatic and manual modes work fine (albeit, again, in a very specific way) would seem to suggest this is not the issue either.

I have read many a post on many a forum, but have not seen anything that seems to address this specific issue.

Does anybody have any ideas where the problem might lie, or think it could still be one of these switches that is causing the issue?

Thanks! Scott