Gearbox Funk

[David's8]

Well you have 2 fault codes indicating the F125 is playing up:

Address 02: Auto Trans Module:
17090 - Transmission Range Sensor (F125)
P0706 - 35-10 - Implausible Signal - Intermittent

and 2.

Address 03: ABS:
01119 - Gear Recognition Signal
35-10 - - - Intermittent

I assume with the "after" printout that the codes were cleared and that the car hasnt been driven after clearing them? Or at least the PRNDS issue hasnt arisen? But it does look like the F125 is acting up.

[HPsauce]

Looks like the usual collection of random crap, nothing significant.
And of course, as suspected, the likely F125 telltales:
01119 - Gear Recognition Signal 35-10 - - - Intermittent
17090 - Transmission Range Sensor (F125) P0706 - 35-10 - Implausible Signal - Intermittent

Not sure about this one, or how significant it is:
18171 - Shift Lock Solenoid (N110) P1763 - 35-00 - Open Circuit
That may be causing other oddness re gears. See: http://wiki.ross-tech.com/wiki/index.php/01236

Importantly there's nothing to indicate any gearbox internal problems.

[Adrian E]

Yeah, when I saw that code I checked and you can move the gear selector out of Park without the footbrake on, so either disconnected or faulty.

Car wasn't driven between scans - just a quick clear to see what appears again before it goes in next week so the codes are known to be current

[HPsauce]

Originally Posted by Adrian E

Yeah, when I saw that code I checked and you can move the gear selector out of Park without the footbrake on, so either disconnected or faulty.

Wasn't there a recall on those switches, might be worth checking that with Audi, might not have been done.

[Adrian E]

That was for a faulty clip on the cable IIRC, which would act as if the brake pedal wasn't down and refuse to move out of park - I remember getting mine done shortly after getting the car. Defo worth a double check though, as maybe someone has bodged it because of the non-repaired recall fault?

[bobbyshafto]

The S8 went in to DSAutowerks yesterday, David replaced the F125 switch and showed me the original, it looked horrendous with a 6-8 inch piece of cable used to extend the original cable which had been very badly done, bits of wire, connectors and tape all over the place! Excellent service from David and at a very reasonable price!

All good so far and for 20-30 minutes after collecting the S8 until the "juddering" returned!

As a new owner of both an Audi and an S8 my description would probably not be very accurate so I checked through the forum and the following thread is pretty much the same as my issue:

http://forum.a8parts.co.uk/showthread.php?t=11766

My only comment is that the issue didn't arise until the fault codes were all cleared recently and whether that is of any relevance at all?

That said, I would be grateful for advice from the forum; as I see it I don't know what the fault is but I am not convinced it is possible to be sure, do I make an assumption and spend, what I expect is, a very large sum of money on a replacement TC, perhaps visit a gearbox specialist or look for other causes?

Many Thanks

Neil

[MikkiJayne]

Probably worth getting the gearbox oil level checked / topped up in the first instance. In my case the TC was damaged by low oil, caused by the PO re-sealing the gearbox sump with bathroom silicone just before I got it On the drive home half the oil escaped through the gaps and trashed the TC.

I fitted a good used TC but they are pretty hard to find unfortunately. A new one from Audi is £1K. You can get rebuilt ones, but I can't vouch for how reliable they are. I'm going to be replacing a rebuilt unit with brand new for someone shortly as the rebuilt one is whining after only 12 months, but I don't know who rebuilt it or how. There may be options from the USA since if anyone knows how to build a torque converter its the Americans! Still investigating that.

If you're brave you can pull the gearbox to change the TC in the car, but personally I drop the engine and gearbox as one and change it on the floor since I find that much easier. Its an 8-10 hour job that way but you can do the cam chain tensioners and oil cooler pipe while its out

[Goran]

They used bathroom silicone on their Audi? On a critical part like the trans sump!
It amazes me the cheap fixes some people do. Although in this case its not really a fix.

There was a old thread on here, a lady called Amanda got a super strength torque converter from the USA for her RS6, which uses the same transmission as a D2 I think?

There's probably more info on audisrs and rs246 if you chose to go for an aftermarket torque converter.

[ainarssems]

There are 2 or 3 different F125 switches with different length cables and connectors, considering that cable has been extended it is possible that gearbox including F125 switch has been swapped in the past and different gearbox put in which might be mismatched either with rear diff or TCU.

So first on the list should be checking fluid level and part number/code on the gearbox and compare it to codes on build sticker and/or rear diff code and TCU part number.

[HPsauce]

I agree with Ainars, proceed cautiously and carefully and check everything.
I'd definitely get VCDS and scan regularly to see what, if anything, appears after you have any "issues".

Don't jump to conclusions, despite the advice re the F125 switch (*which seems well-founded).