A4 B6 CVT TCU HELP repaired but NO GEARS HELP !!?

Hi all

Audi A4 B6 CVT autobox: NO GEARS ENGAGING please HELP !

I was having slight issues with the dashboard PRNDS lights flashing when the car got warm and I selected reverse, sometimes the car would not engage reverse, but after moving into Park then back to reverse it would engage, the PRNDS then would stop flashing when selecting D again.
This was the only issue I had, I got the codes read and it stated:

17090 - Transmission Range Sensor (F125): Implausible Signal.

I decided to remove the TCU from the back of the CVT box, inside the TCU I saw that there was gearbox oil and loose contacts, I could see it had been repaired before as the sealant had leaked ! I re-soldered 2 contacts and re-sealed the unit properly, put it back on the car but after about 10 secs the dash beeps and I get the BRAKE warning, ABS and TRACTION control lights on dash with NO GEARS so the car is stuck!!! The fault code is:

P1647

I took the TCU off again and took it to a repair place locally, he said there were other loose connection that he repaired and he tested the unit and all was working and fixed or so I believed !?
But I have put the TCU back on the car and the same problem as with no gears and warning on dash is still there !?

I have tried disconnecting the battery thats all, is there anything I can do now HELP !?

I found this on the site for an A6 it might help point you in the right direction.

So an update if anyone stumbles across this problem.

After much searching and many vag com plug ins I managed to figure out that the abs module had lost its coding somehow. I was told the gearbox had been replaced at some point if that would cause a problem?

So it was quite easy. Plug in the vag com and open the program, turn ignition on.

Go to options and test the link, all ok.

Go to abs, coding, change the code from 00032 to 00011 in the soft code box, press do it!

The light on the dash turns off https://www.audiforums.com/forum/ima...es/biggrin.gif happy days.

Press exit, exit, exit until the program closes, turn off ignition, unplug vag com lead.

Whilst I was there I turned off the active gearbox setting by going into the transmission button and the same as the abs change the code from 00000 to 00010,

Hi.

Im having the same issue with my wife`s car. Its a 2004 1.9tdi CVT.
PRNDS is flashing wich i guess is the Gearbox TCU playing up.
Question: is it difficult to take the gearbox out? do i need any special Audi tool?
thanks in advance

I not sure about the 1.9tdi, but if its the same CVT gearbox then you do not need to remove it, only drain the oil and remove the cross support brace to access the TCU.
However be carefull as although there are plenty of companies that say they can fix it there is no gaurantee of 100% and what happened to me was when I removed the TCU I found that it had been repaired before so this with the 2nd time !
Unfortunately for me it did not get fixed (despite the company advising it was fixed) and I was left with a car that was not drivable ! I had no option but to buy a new TCU and in total cost me £1500 to fix the car !!

My advise is if the lights on the dash flash and you sometimes do not get reverse, try moving into Park then back to reverse and if you can live with that, then so be it.

The TCU is a PCB with fine wires that can become loose inside from the solder joints, any slip can damage the circuit !

Thank you for the info.
I will get the car on ramp over the weekend and have a look at the gearbox. Hopefully does not need to come out. If yes i will leave it as it is..

No gears at all usually signifies the box has failed internally and needs to be stripped. I bought a 2009 A6 2L TDI like this over two years ago as the owner wanted out after seeing the estimate.

h