Changing the F125 - can it be easier?

[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?

[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.