Same solenoid pattern in Park, Reverse and Third

[Addicted]

Due to the lack of available data for my Audi 4 speed transmission I took it upon myself to datalog the outputs from the Bosch TCU fitted by the factory to gather the required info for a megashift instalation.

However.. the datalogs show that the solenoids are in the same state in Park, Reverse and Third gear.

My pukka datalogs are too large to be attached, but I have attached a truncated example. N88 through N94 are the seven solenoids. N93 is PWM for pressure control. I believe N90 is the TCC solenoid...

Reverse is not shown on this short datalog, but its the same as third.. i.e all solenoids are OFF..

This transmission has a shift cable from the lever, so its not 100% electronic I think, could it be that Reverse is activated mechanically via the cable?

[Bernard Fife]

However.. the datalogs show that the solenoids are in the same state in Park, Reverse and Third gear.

Addicted,

This could be an issue with the solenoid states, but is more likely an error in the way these states are reported. I will have a look.

could it be that Reverse is activated mechanically via the cable?

That's not unlikely at all. Many transmissions select P, N, and R mechanically - to allow limp-home abilities in case of an electrical failure.

Lance.

[Bernard Fife]

Addicted,

Unfortunately, that spreadsheet is of no use to me for diagnosing the problem. Please post an excerpt of the original log (including the header lines at the top). You can shorten a datalog in any text editor (such as notepad.exe in windows) by removing any number of whole data lines after the headers and saving the file.

Please post your MSQ settings file as well.

Lance.

[Addicted]

Hi Lance, I'm not using a MS product to do the datalog. Its an Arduino Mega2560 with a couple of project shields added with opto isolators to monitor the solenoids etc.. so the xls is pretty much what I'm writing to the SD card (as a CSV file)

I need to sit down and go back and double and triple check the wiring as I've now had it confirmed that Reverse IS selected hydraulically. Over the last 4/5 months I've collected all sorts of factory documentation on this gearbox and its quite contradictory.. between 1990 and 1993 the shift pattern changed 3 times! early boxes had 'drive split' between 3 and 4 and TCC on 3 and 4.. later ones have no drive split and TCC only available in 4th.. all very confusing. Especially as my gearbox is from a car registered in 1992!

2 years ago I should have pulled this transmission and swapped in either an early non electronic trans or a post 1995 5 speed! You live and learn, and I've learnt a lot recently!

[Bernard Fife]

Addicted,

It would be helpful to have a datalog and the MSQ (i.e. hook a laptop up to the GPIO board). They contain much, much more diagnostic information besides just what is on and off, and that can be very helpful in figuring out what is going wrong.

Lance.

[Addicted]

Lance, my GPIO board is on the bench. I'm datalogging the Bosch 097 TCU in order to gather the data needed to build/configure the GPIO

As far as I can tell no one has successfully implemented MegaShift on the VW/Audi transmission. There was user called KamiKazeTuner that was building one, but vanished into the ether. There was also a chap in Germany, but I think his posts were lost when the forum had the server problems.


P.S
I've added a datalog from the weekend. Basically me driving out of my village to the highway, run up to approx 70mph to ensure 4th gear then return. Immediatly before pulling into my driveway I stopped the car, reversed back and then forward again, then reversed again before pulling into my driveway.

[Bernard Fife]

Addicted,

I apologize, I didn't read your original post carefully enough. I thought you meant that MShift was in control and erroneously commanding the same solenoid states in P, R and 3rd (and that is why I asked for a datalog and MSQ).

But do I now understand correctly that you are saying that the OEM controller is commanding the same states in P, R and 3rd, so that the shifter cable must be controlling the hydraulic circuits to differentiate between these?

If so, that isn't unusual. For example, GM does this with PNR and 3rd gear is selected when all the solenoid are off IIRC (so that the vehicle can still be driven even if there is a complete electrical failure). In fact, with GM 4LXE trans first gear can be selected via the solenoids, but a different, stronger power path is used if the gear lever is moved to the low gear position to alter the hydraulic states.

So the type of strategy you are seeing wouldn't surprise me at all.

If you trans is having the same solenoids selected in P, R, & 3rd then you should imitate this with MShift, and use the gear lever to select between then, as per the stock setup.

Lance.