Changing the F125 - can it be easier?

[HPsauce]

PROGRESS! Of sorts -----
Went for a short local drive and pretty soon (without me touching the stick) the red background on the D went out.
Played around a bit and Sport mode seemed to work as did the Tiptronic, so it was driving reasonably normally, though even in Tip mode there was no highlighting of the selected gear!

I think it was then sort of "stuck" in Sport mode, but not 100% sure, so drove home and parked the car and turned ignition off while in D.
Connected up VCDS, ignition on and had a peek - F125 code was 1111! (Plus of course codes stored about implausible signals)

Moved the shifter around and all other positions were normal (including P at 1000).
I note my earlier comment that "There can also, looking at the tracks, theoretically be a 1111 code between D and S" so I'm wondering what's going on inside.

I did then manoeuvre into my normal parking place which involves a fair bit of shuffling back and forth, during that it all went back to normal!

[HPsauce]

Originally Posted by HPsauce

I'm wondering what's going on inside.

Looking at the insides of the F125 it's track 3 that's relevant and there's a thin section of it between N and 4/S so I think that contact must be damaged and just touching that thin strip at times when in D.

[briang9]

As Stephen has alluded to, they don’t like not being driven and in my experience the F125 can be susceptible to damp, particularly at this time of year when not used much, hopefully it might sort itself out with a bit more use to help dry it out, mine did this a few times and after a few days driving it went back to normal

[HPsauce]

Thanks Brian, I'll see how it goes over the next few days, though the weather here has been pretty dry of late.

These are definitely not the symptoms I've seen in the past so I'm not feeling that positive if I'm honest, though oddly in my testing today it didn't go into limp mode, just lost the highlighting of the selection/gear.

I suspect that is because the code the TCU is seeing (1111) is valid as a transition between D and S so it's sort of "lost" but not concerned enough to throw limp mode.

Has anyone else ever seen that loss of gear selection highlighting on their DIS? It's quite odd, you know something is wrong but you have to think hard about what it is. It's definitely not a fault in the DIS itself though.

[HPsauce]

So an interesting test today. Started all looking normal but after a few hundred yards the D highlight went out.
From then on the car generally started behaving as if in Sport mode - late upshifts, quick downshifts, higher revs etc. Though I did before long flip into "real" S mode which worked as it should with highlights on the S and gear numbers if I used the Tiptronic buttons on the steering wheel.

I pottered around in 30/40mph limits locally and noticed that when I engaged Cruise Control it immediately felt as if it was back in D, not S. That was 100% the case over a few minutes of back streets including some reversing. After a reverse the D symbol illuminated only very briefly and behaviour reverted to S style.

BUT oddly after a little while more, without me doing anything, it changed to normal D behaviour (Only, no highlights in the DIS) and stayed that way for a few miles until I got home.
Handbrake on, foot on brake pedal, didn't touch the shifter! Grabbed VCDS laptop from the glove box and plugged it in - F125 definitely showing. Z3/1111.

So basically at present it's driveable as I can use the Tip buttons to upshift if it's inappropriately stuck in S mode. And if it drops into D without me doing anything that's fine.

Anyone got any thoughts on that?

[steamship]

Originally Posted by HPsauce

Has anyone else ever seen that loss of gear selection highlighting on their DIS?

When I had issues with the F125 switch, it was always a case of it going into limp mode i.e. everything highlighted, and usually happened after being in reverse. A restart sorted it out, but never had the occasion where the DIS wasn't illuminating the current gear. As you mentioned in a previous comment, it sounds like some 'crud' wandering around inside it.

[HPsauce]

Originally Posted by steamship

When I had issues with the F125 switch, it was always a case of it going into limp mode i.e. everything highlighted

Indeed Sean, same here, and for most others I think. But this doesn't generally go into limp mode.
In fact it was going into limp mode that drew my attention, but it could have been "non-highlighting" for a while, especially in cold weather when the DIS has faded away and takes ages to reappear!

Insurance policy; as I happen to be nearing the end of an Amazon Prime free trial I had a quick look at suppliers there. Found some cheap Chinese copies "SURIEEN" branded in UK stock and less than £40 so that will arrive tomorrow.

If I do pay a garage to do the job I'll obviously try to get a genuine one, though if it means going to Audi Tradition I might not......

[HPsauce]

Originally Posted by HPsauce

So an interesting test today. Started all looking normal but after a few hundred yards the D highlight went out.

Exactly the same today, except it just carried on behaving totally normally as if in D.
I did try cruise control a few times, all fine, but DIDN'T use Sport at all.

Drove about 10 miles, came home and did the same as yesterday. Handbrake on, foot on brake pedal, didn't touch the shifter! Grabbed VCDS laptop from the glove box and plugged it in - F125 definitely showing. Z3/1111.

Also looked for error codes, none in the Gearbox ECU today!

[ainarssems]

Never had to do anything with auto linkage but here are my thoughts.

Where is the selector position fixed? At the lever or on the gearbox? If it's at the lever, is there any adjustment for linkage between lever and box. Maybe when it's in drive at the lever it is between drive and S in the box and needs a slight linkage adjustment.

[HPsauce]

Thanks Ainars, I did wonder about linkage/adjustment but I've ruled that out.
Main reason is that I've been moving the selector lever very slowly and carefully through the range and everything is in exactly the right place initially as monitored with VCDS.

Then when the symptoms appear (no highlight on D) everything is STILL in the right place EXCEPT D is replaced by Z3. i.e. Track 3 is signalling.

When you look at the track layout inside the F125 (attached) it's the gap/narrowing of track 3 between N and 4 that is the relevant area, the rotary arm is picking up a contact throughout that and shouldn't be.
Remember with a PRNDS shift like mine S is 4 and gears 3 and 2 are not reached.

As you can probably see in that picture there are two contacts against the metal tracks as each circuit has two narrow contact levers.
My guess is that one of them is bent or carrying a piece of conducting debris.