Here is Marco's setup before the real thing.
The little switch activates the tip mode and the two buttons up/down shift. It only works in D. Any other F125 switch position cancels the tip.
<img src="http://pictureposter.audiworld.com/80635/img_0245.jpg">

 

I've found Marco's old post and looks like you can't ground the F189 permanently.
This is from his post.
"when you put it in reverse just shift the shifter to reverse. and then back to drive. One this I have found is that if you don't turn off the trip switch first then go back to drive your will not be able to trip... turn off trip first then you can go back to drive turn on and go. If you forget to do so just put back in park turn off the trip switch and then go back to drive and turn trip back on. enjoy.. It is a very easy mod and very cheap. Best of all it was fun and you will have fun driving.. If you follow pauls write up you just hook up the other end to the switches as such.. (if you use cat 5 wire) Blue and a ground to one siwtch this is the the one that turns on the tip (trip switch). the orange and a ground to the up shift switch and the green and ground to the downshift. and have fun."

 

that the tip switch is a momentary contact switch, and i need to use it (mimic it) as such.

from your post, it looks like someone might have done something very similar (marco?) any chance of pointing me in his direction?

 

a8drifter made his own paddle shifter.
http://account.audiworld.com/users/77296.phtml
<img src="http://pictureposter.audiworld.com/77296/100_0270t.jpg"><ul><li><a href="http://account.audiworld.com/users/80635.phtml">http://account.audiworld.com/users/80635.phtml</a</li></ul>

 

Hello Dave,

I miscommunicated somewhere along the way, because I am and always have been 100% in agreement with Tozo that it is safe to engage an extra Tip enable switch when the gear lever is in D, and that the F125 switch does not move when you slide the gear lever right in to Tip.

The trouble comes if it's in Tip when not in D. From what tozoM8 reports, it seems that all that happens if you engage Tip when in R (or PN432?) is that it won't engage Tip until you next shift into park and release the switch. Not too big a deal. You could probably live with it.

I did not agree with Tozo that "The shifter wiring must be different to recognise S instead of 4th" in a 2002 or newer car. This mattered not to your proposed approach, but for trying to determine whether 2002 A8s (which have the desired Tip-in-D function) have a different TCM to recognize the PRNDS shifter even with 00032 coding, which they must if the F125 switch and wiring stayed the same. If they had the same TCM, the next question would have been whether recoding or adapting the TCM could enable the Tip-in-D function without you having to build any new hardware.

I just called the dealer whose parts list showed four or five TCM versions for 2001, and another four or five for 2002, with some overlap. How's that for inconclusive?

Tom

 

Your fundamental idea is a relay (or transistor equivalent) across the gear lever's Tip enable switch, that would be engaged for a period of time after the driver clicks the steering wheel + or - gearchange buttons.

Here's a summary of what a full-featured, indistinguishable-from-factory implementation should probably do, combining your ideas and maybe some new ones. You might be happy without this complication, but ignoring A(1) means that the transmission may lock out subsequent Tip requests if a steering wheel button is clicked with the shift lever in the wrong position, and ignoring B(1) may keep the scheme from working at all. It seems like a microcontroller such as a Basic Stamp might be a decent way to implement this.

A. Clicking + or - on the steering wheel should engage the Tip relay only if
(1) the gear lever is in D, and
(2) the lever is not already in Tip.
(1) keeps the TCM from locking out Tip if the relay engages with the lever in the wrong position. D can be detected by reading four wires between F125 and the TCM. (2) prevents our relay timer from keeping Tip momentarily engaged after the driver moves the lever out of Tip just after shifting.

B. If the TCM ignores + and - signals which precede Tip engagement (seems likely), the steering wheel + and - will need to be unwired from the TCM and go instead into your box, which will forward them to the TCM
(1) a moment after engaging the Tip relay if it wasn't engaged but is allowed to be, or
(2) immediately in all other circumstances -- e.g. no delay if the lever or relay are already in Tip.

C. After being engaged, the tip relay disengages
(1) a certain amount of time after a steering wheel +/- button last transitioned from not pushed to pushed, meaning that holding the button (or a short) won't keep it in Tip, or
(2) immediately if the shift lever leaves D or moves to the Tip position.
Detecting whether the lever has moved to the Tip position while the Tip relay is engaged involves reading the Tip switch output on the switch side of the blocking diode, but putting the Tip relay on the TCM side of the diode. If there is no diode, one will need to be added, possibly inside the box.

It's an interesting project. I'll buy one if you make them. Such a product should be applicable to other Audis &amp; VWs. Sorry I don't have time to work more on it.

Tom