skiwi

tcm/13 is the tip switch recognition in all the 01, 02 or 03 cars...

i'm going to check again, this time making sure that i use the tcm ground to check (terminal 28).

skiwi

another way of doing this occurs to me...

given that the tiptronic switch (f189) is a physical microswitch mounted on the tiptronic selector (on the side of the gear lever), i could run the relay to the contacts of the microswitch. in that way the relay, on selection of the steering wheel tip button, could "close" the microswitch circuit 1/4 sec before the tip button is asserted.

the only remaining challenge is to "read" the gear lever selector to ensure "d" is selected.

ttuling

... according to the ZF 5HP24A parts manual.

The 2002-3 model year A8s have their own Audi and ZF part numbers for the transmission in the parts manual, but the same F125 switch as in 2001. So the 2002 TCM must be programmed to recognize what was the 4 lever position as S. I'm willing to bet that the 2002 TCM has a different part number -- I'd be surprised if pre-2002 TCMs support the PRNDS lever. Chances are that's when they added the software for steering wheel tip in D.

So I'm not too optimistic about finding a TCM which will do what we want, unless the 2002 TCM can be coded to work with a PRND432 lever while preserving steering wheel tip in D, which would be nice but probably isn't there.

Tom

tozoM8

However the 97' switch has 8 pins the 03' has 9. the 03' tranny went into my 97' A8 without problem. I just put the 97' switch on the 03' tranny. the output speed sensor and the solenoid wiring harness is the same. The shifter wiring must be different to recognise S instead of 4th.

ttuling

If the TCM changed for 2002, there is little reason to hope that earlier ones contain the software to allow steering wheel Tip shifting in D.

ZF shows the ten pin switch (of which only nine appear on the Audi wiring diagram) starting in 2000. The difference is that with the newer switch, the TCM can still see the lever position even if the backup light fuse blows.

Tom

tozoM8

The pre-facelift has a round plug with 8 pins.
<img src="http://pictureposter.audiworld.com/80919/dscn2203.jpg">

tozoM8

When you move the shifter to the right in D the F125 switch doesn't move. You are activating another micro switch F189. F 189 contains 3 switches. One on the back of the shifter assembly to activate tiptronic and 2 switches for up/down shift. You can use a separate switch to activate tiptronic or you can ground the signal from the TCU permanently. Tip mode still will be activated only in D. Any other position of the F125 switch is canceling tip.

ttuling

The point was that 2002s could behave as they do (S instead of 4th, steering wheel Tip in D from the factory) using the same F125 and wiring as 2001s. This suggests that the 2002 changes are in the TCM, so the steering wheel Tip in D behavior that Skiwi and I want is not proven to exist in our pre-2002 TCMs (and probably doesn't).

In fact, I'd bet that plugging a 2002 TCM into a 2001 car gives PRNDS shifting and, if coded to allow it, Tip in D. Wonder what happens in lever positions 3 or 2.

Also, I can't reconcile the transmission having a Tiptronic recognition switch short to ground trouble code with any assertion that it is legitimate to ground the Tip enable in lever positions other than D. The TCM may well cancel Tip when F125 moves away from D with the Tip enable grounded (on), but it will likely also set a trouble code. And then what? Limp home?

Tom

skiwi

in essence, as long as you can move that micro-switch, forcing tip mode, *before* you hit the steering up/down, you'd be ok. the tcm wouldn't know the difference.

however, i'm interested in your assertion that "Tip mode still will be activated only in D. Any other position of the F125 switch is canceling tip."

could you elaborate on the reason for this? is this a physical interlock between the f125 and f189 switches???

skiwi

tom,

i'm interested in what you are saying, and want to get it through my head.

you think that the tcm might ignore a "tip enable" signal (f189 triggered) as the f125 switch is telling the tcm that it is in "d" mode and therefore illegal, and that, in this instance, the likely behaviour is to throw a code and go for a sulk?

i guess that a test is in order, along the lines of:
1) locate the f189 connection (t10g/6 in the plenum)
2) run a switch between it the tcm electornics ground (location 102, need to find it).
3) go for a drive in "d"
4) close the switch
5) see if the tip switches work.

i've got a long week-end coming up so will be able to do it then unless either you or tozom8 can do it sooner.

i need to ask though, how do you get your tranny out of "limp" mode?

:-)