DocHP

Got a -95 Audi A6 Quattro with automatic transmission thats acting up on me.
Its the 2.6L (ABC engine).

I have found alot of reading in the forums about tranny problems but nothing really like mine.
Took me a week just to read all threads

First up, the problem.
When im in 4th gear and brakes to a complete stop, or brakes so its shifts down, i can hear that it stay in 4th really long and then with a hard downshift it goes to 2nd.
This happens 50% of the times when i brake, but if i´m a little softer and brake slowly to a stop it works. Or put in 3rd gear manually.
If i hear this hard shift from 4th to 2nd, the gear is stuck in 2nd and it wont shift up. (gear indicator shows D)
Reverse working, back up light working, brake lights working. It doesnt move from 2nd in D or 3.
I clear the codes, and everything works again.

Everytime i hear/feel this hard downshift from 4th to 2nd i get this error code
00652 - Gear Monitoring
27-10 - Implausible Signal - Intermittent

The oil and is changed a month ago by the previous owner at a Audi dealer, didnt solve the problem.

When the car and transmission is working, its gears up and down smooth and soft, no hard shifting or anything.
No other fault codes is found, only for the engine (oxygene sensor left).

The brake warning light is on flashing, i have thought its about the "wear indicator" for the brake pads, but now i think it may be something regarding this error.

Annother thing i have noticed, when i press on the brake pedal standing still, i can hear something move a little under the gear stick/shifter. Its almost like something isnt tightened or have a few milimeters movement. If this is normal or not i dont know, bought this car for less than $500 to use over the winter and trying to fix it.

Anyone have a idea where to start?
I got vcds/vag-com if anyone knows any blocks or functions to check.

Sorry for my bad english, i´m from Sweden and i hope you understand anyway

Prospeeder

The brake pad warning if the sensors are good is the instrument cluster. Eventually it will start giving false low oil pressure warnings too.

As far as the trans. Gear monitering. So speed sensor is what that would sound like, there are input and output. Only way it can moniter a gear. I have all data at work, i will see if they show a diag tree for that code. See if you can view the data blocks and see if a speed signal drops off or becomes radicly different when it happens. Reason its going into 2nd and getting stuck is limp mode to "protect" it. False speed sensor readings, Internal slippage, stuck valve body solenoid or damage in the valve body like a broken spring would cause no shift and force the trans to limp mode.

DocHP

Thank you for your reply.

Its not in limp, its just wont shift from 2nd. (may be limp anyway, but it just dont show it)
Lights in the gear selector panel are blown, but i can se the shadow around D or what gear i have selected. D, 1, 2, 3 is the same, stuck in 2nd

One or two times the last week it has gone in limp, all gears have dark shadow in the selector.

If i turn the key off/on or just stops and turn off the car and starts again it works 50% of the times, otherwise i need to remove the error code.

I have ordered the speed sensor G68, it was only $20 so a cheap test.

i have seen threads about "2 or more wheel speed sensors fail", is this the ABS sensors?
My ABS is working perfectly, or can this be faulty anyway and mess up info to TCM so i get the code?

Prospeeder

I dont think ABS stuff has anything to do with it, its input signals independent of that stuff. If its truley sticking in second you need a new valve body. common issue with ZF transmissions of this era. Plenty of ZF trans bmws have similar issues. I have a 740i with a bad valve body and will stick in 5th occasionally and set limp mode.

DocHP

New valve body may solve the problem, but i´m interested why and what is happening

I have noticed that i do not need to remove the error code, if i let the car off for 2-3 minutes, i can drive again and all gears works perfect. Until i brake hard so it jumps from 4th-2nd.

I have bought a usb cable so i can drive and log whats happening.

I also have noticed that it isnt when i brake the problem occurs, its when i brake hard and after that accelerate from zero.
It shifts one time, then i can se on the RPM roughly about 2000rpm it jumps 100rpm and continues to accelerate without changing to 3rd. Its stuck like this until i turn off the car and start it again.

So it must be when this happen the error code is put.

If anyone have any tips or trix, im happy to receive them in my adventure
I will hunt this problem down just to know, and learn.
May be cheaper just to change, but learning is not free either.

Next up is to change the speed sensor located on the left drive axle. I also going to change the "drive joint", dont know the english word for it. When i turn left i can hear tick-tick-tick-tick from the joint, that one
I have read some having troubles with this bad, and i need to change it anyways.

Prospeeder

Not sure what your wanting to learn. The code is set because of the probem. The code isnt the problem. The valve body has doezens of springs and check *****. The springs break or relax, the ***** wear out, things also stick, bind, wear grooves ect ect. plain and simple, get a rebuilt valve body assembly and fix your car. If your bave get your own valve body rebuild kit and do it yourself.

DocHP

Almost a year after, winter coming up and the Quattro is out for the winter again.

Have read alot this summer, amost got 200 forum pages saved in my computer.
I have also tested almost every little cable in the car, from TCM to gearbox, from sensors and everything.
VSS and other speed sensors were changed early.

I ended up with two possible errors.
1. Previous owner lied about fixing the gearbox
2. Gearbox is crap

So, i made it easy, jacked up the car on the pass-side and added 0.6L ATF oil, just to see if it made any change.

After this little addition the car gears normally, no thumps, no sticking in 3rd, no loosing of gear when i turn or something.
Now its on the jack stands to make a proper refill and filter change tomorrow.

I wish i was smarter last year than just trust the PO about the 100% fixed oil change.

Prospeeder

you want to put the car level, running, open the fill plug and if nothing drips out its low fill till it runs out and replace the plug. You will cause permanent damage running low on fluid, even if it seems to shift ok or better

DocHP

Had it on jack stands this night and checked ATF-level earlier and measured temperature with vag-com
Added almost 0.5L more, so totally 1,1L too low

Now i hardly notice it shifting

Prospeeder

check the gear oil in the front differential too. If a bunch of atf runs out theres where your atf is going. If its low, then just fill with synthetic gear oil till it runs out. Car level of course. If you let it get too low, or let atf get in there, then it will destroy the bearings in the differential and basically make the transmission junk.