Let me, before I start into what I did, explain what the difference between the two types of "calibrations" that the AW55-50SN can do. You have a Control Module Adaptation (CMA) and you have a Reset the Adaptation (RA).
The CMA is akin to writing new lines on a blank piece of paper. The TCM (Transmission Control Module) knows about where the lines should be and by going through a series of controlled shifts, it writes the lines that the trans will follow. When you do something big to the trans like a new/rebuilt Valve Body, new/rebuilt Linear Solenoids or even replace leaking internal gaskets, you should do a CMA since the "lines" will now be different to the TCM.
The RA is like a school text book where someone took notes in it. You can read the book, but off to the side, you get the answers the teacher really wants and you get an "A" in the class thanks to Bob, Class of '62! The TCM is always learning and taking notes. Those notes are great for the current set up, but they need to be erased and start over when you do something simple like change the fluid. Resetting the learning back to a known set of good values.
- Sven on the way home.
I picked up a well trod 2003 V70 T5, named Sven. It ran fine, but had a massive 2-3 and 3-4 shift that if it caught you off guard would try to rip the car out from under you. Additionally some of the down shifts nearly stopped the car and put me up against the belts at times. Driving it in Geartronic (manual shift) Mode helped as you could feather it between the gears going up and shift down at the stops. Forget up shifting in the corners... it was scary coming out! So, with the help of the MVS gang, I set about the basics to try and recover Sven's trans without replacing it.
There is a oft spoken wisdom about working with flares and hard shifts in the AW55-50SN transmissions no matter what car they are in. They are:
- 1) Fluid Changes
- 2) B4 Update (if applicable)
- 3) Reflash TCU (if applicable)
- 4) Reset the Adaptation
- 5) Valve Body Rebuild/Swap
and finally...
- 6) Replacement of Trans.
The B4 Update (well documented elsewhere on MVS and elsewhere) was easy and cheap. Mine had not been done as there was an AK3 on the cover. Current appears to be AK4 on my replacement and in pics documenting the procedure. A few choice words and scrapped fingers later and it was in. NOW here is where things started to go awry without me knowing. The B4 update should require a CMA, as it changes a core component of the transmission, but reading the instructions, they just say to do a RA and away you go. So with the help of a local Volvo Nut with VIDA, we did the RA and I drove off into the sunset... till it shifted into 3rd! weeeeeeee...Clunk!
OK, I was going to have to go into the trans to cure what ailed Sven! I got a Valve Body off eBay and was intent on swapping it in until I did a little more research on the Linear Solenoids that control the AW55-50SN. Again, a fairly well documented procedure (I'll post a follow up with all the links I used to get me through) that with a couple of tools and the holding of the tongue in various positions, was easily completed and appeared to be successful. They now were smooth as silk. I reinstalled all 3 "SL" Solenoids along with a donor set of known good "S" Valves (the ones that control gears) and filled Sven to the line with fresh ATF, performed a RA (again, should have been a CMA) and took him out for a putt around the block.
And low and behold... it got better. Not perfect but better. I was also told that it took several hundred miles to "learn" fully (more on this later). So I set about driving it as much as I could. It got better, but there were still issues with flares. Much smaller but still present and different. I had read many trans repair posts about where cars were fixed, but issues remained and were lived with. I'm not like that and knew that I'd fix them... even if it took replacing the trans.
This could get expensive...
Will our Hero fix the trans or will the Evil AW55-50SN rule the Universe? Stay tuned for the next exciting episode...
