Transit 2.0 rwd ratio change cruise not working

[Toshiba1306]

Hi, transit mk8 rwd 2.0 Ecoblue 2018 European.
After changed rear diff ratio from 3.5 to 3.15 my cruise control stopped working. I've set up everywhere I could new ratio, changed tyre diameter by the calculator provided on this forum, NO LUCK. The only fault I have at Reading data, once I choose in PCM cruise control is lost communication with CCM. No other faults, ABS sensors reads properly etc. Buttons on steering wheels works, everything shows on dash, but cruise doesn't engage in any gear and at any speed.
SECOND thing I noticed after ratio change, once I "send" van through 4 and 5 gear, the revs goes up automatically without touching the gas pedal. But it only happens from 4 to 5 and 5 to 6th gear. Once I drives gently, it doesn't happen. Really annoying.
Anyone had this issue? Looked I guess everywhere and didn't find any help with it.
Thanks.

[bolhalovas]

Maybe PCM firmware reflash required. If you send me the VINs (yours and donor car) I can check it for you.

[Toshiba1306]

I thought so tbf
I only have mine VIN, the diff ratio pinion was provided from guys who supply them and fix diffs

[bolhalovas]

Maybe I'm able to find a matching VIN with this diff ratio. Just send yours VIN.

[Toshiba1306]

WF0XXXTTGXJJ13488
Thanks in advance.

[Toshiba1306]

Maybe I'm able to find a matching VIN with this diff ratio. Just send yours VIN.

Any luck?

[bolhalovas]

Sorry, I was busy...
So, your current PCM firmware should be GK31-140C204-LAB. To 3.15 ratio I found GK31-140C204-KAB. You can upload it with Forscan Beta and a decent J2534 adapter.

[Toshiba1306]

Thank You. The new firmware can be downloaded somewhere? Or is it based already in new forscan beta?
Sorry, for maybe silly question, I need to find anyway someone to reflash new firmware as I am new to this, and don't want to break something.

[bolhalovas]

Please read first the relevant topics about firmware update procedure!
File from my Drive: https://drive.google.com/file/d/1YCryOu ... sp=sharing

[Toshiba1306]

I think I'll use my friend to do this once I have the file already. Thank You very much Sir!
Hope it will sort out my issue.