ZF8, Winter mode selection

A very simple question, but I could not find the answer either in the documentation (nothing on ZF8, really) or this forum to date. In the Transmission - Shift Scheduling section, there are three winter selectors, namely Winter, Winter A and Winter B. Any clues as to how each mode is selected and what drives this selection? Is this something that can be modified? Right now, it seems it points to maps 25, 28, and 32, where 28 does not have really data (all values set to 10k), and pattern 25 seems to have very high values that make little sense when gear ratios are applied to them (it seems fake, really). It stands to reason that pattern 32 is the one that us really used, but there is no indication this is indeed the case.

Attachment 105774

Has anybody looked into these before and could share any experience, please?

Thanks in advance !

There are THREE different winter shifting modes in the ZF8, and they may or may not be used depending on calibration.

First there's a gearbox selected "Winter" mode. Depending on vehicle, you may be able to select a Snow/Winter/etc mode.
There are two possible tables used here, shown as Winter A and Winter B.. Often time one of those tables is inactive (if you check your Shift Pattern Mapping, 28 is probably mapped to actually look at some other table, like 5) and only the other is used.

Next, there's a two modules that may work together, depending on how the OEM configured the ZF8:
- ESC, if used Shift ID 26 becomes active. This is triggered based on the Transmission receiving a message from another module indicating a stability control request is active. If used, the shift table switches to ESC (to do whatever the manufacturer desires, resist upshift, force upshift, etc, based on output shaft speeds)
- The one labelled simply "Winter", uses Shift ID 25. This can take its input from both the ESC system, or internally from a transmission slip detection module. The transmission "slip detection" uses wheel speed information to determine whether or not you're slipping.


Your Shift ID 25 map looks like it was designed to PREVENT upshifts until basically redline, and hold off on downshifting as well.



The easiest way to really see is to log your Shift Source Base and Shift ID parameters, which at any moment will indicate both the Module that is controlling your shifts, and the Shift ID that most heavily influences the current shift choice (it can blend up to 4 tables together at once!)

Thank you, Steven

Checking in the Shift Pattern Mapping Table, indeed, I see what follows: Shift ID 26 (ESC) and Shift ID 25 (Winter) both point to Transmission Shift Pattern 25, which prevents upshifts as you described above. I have not seen this mode engage yet in all the driving I have done to date. It might be a tad difficult with TDI engine, with all the low end torque and quarto traction system, but I am curious whether I can get the car into a controller slip when ESC mode would engage. I just need to wait for the roads to get more ice covered or find a nice patch of mud :)

As far as Winter A and Winter B modes, they both point back to Transmission Shift Pattern 6, which is what seems to be used for my everyday driving predominantly, at least as far as I can log using the Scanner.

Since I do not have a dedicated Winter / Snow mode on the selector, I assume that it is all theoretical either way, and the transmission will not get into the Winter mode anyway?

Kind of along the same lines... has anyone figured out how to make the transmission (in manual mode) start from a standstill in a gear other than first?

For me at least, the ability to start off in 2nd or 3rd would be a good approximation of "winter mode".

I would be one of my next questions. Having Q5 TDI, this is not a big deal for me, since the RPMs are low, but it would be great to start from 2nd on slippery roads.

Quote:

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Originally Posted by ELaw

Kind of along the same lines... has anyone figured out how to make the transmission (in manual mode) start from a standstill in a gear other than first?

For me at least, the ability to start off in 2nd or 3rd would be a good approximation of "winter mode".

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This is possible on the Dodge ZF8s, where I found standstill tables that control this, but I never found those same ones in any of the VW/Audi ones.
My guess would be to try adjusting the shift maps to not force a downshift (so set the 2->1s to 0 OSS) for the shift patterns you're interested in (27,40,46,47 are the ones depending on your "shift situation"/drive mode), and then in the OSS Limits section make sure to also allow the UPSHIFT to be commanded at 0 OSS.

If this doesn't work, I can try seeing if there's some other limit similar to how there was on Dodge.
The Dodge ZF8 code specifically had a check that if OSS was less than a certain speed, shift logic was controlled by a special standstill stuff, and I figured it out initially as a Hellcat for example would let you start in 2nd gear and tracking down HOW I found it. I may need to see if something exists similarly for VW/Audi if my thoughts above don't work.

I initially did the development testing in an RS7 and I don't recall if it let me shift to 2nd at a stop or not manually.

I tried to do a manual shift to second at stop and it was a no go, unfortunately. That was done obviously with no changes to map at all at this time.

I did a full log from the morning start on the cold engine (been down for 2 days, no use) and even with below freezing temperatures, I do not see warmup mode tables (30/31) used at all. The transmission uses table 1/6/11 without a fail. When are warmup tables used then, if at all? Is there a need for much lower temperature or something? It was around -5C today in the morning when I started the car.

I can share the whole Scanner log if that helps at all.