Fast Shifting

[GHuggins]

I deleted all of the 4wd stuff from the harness so there is no way for it communicate that information between the ECM and TCM.
So this thing has been doing this for a couple of years now and I've just been dealing with it.
We I say, my wife and I have just been enjoying the car. Taking it to shows and cruse in's and what not.
It took me a decade to build to the dam thing!
I can manually shift it and it runs like a scalded dog.
For what ever reason when a rewrite is thrown at it, it works until it is keyed off and then keyed back on.

That was typically when the self test took place - every key on after a complete power down. It would probably do it after a full write if you waited a couple of minutes. I don't remember what the manual tcase setup looked for so the tcm would know it was in low range. The auto's had a separate switch input plus the motor's positions. It's the one that did the self test after each complete power down which could cause it's own problems on the ones with weak shift motors. It may have even had a naturally closed circuit that it opened. I really don't remember and without looking at schematics and operations I couldn't tell you for sure. I do know it should be fixed with the 2wd OS as the low range shift scheduling becomes null and void at that point.

[ScottR65]

After the complete rewrite it didn't work until a few minutes later. Weird!
Thanks a bunch!!! I will report back !!

[ScottR65]

What would be the best route to flash a 2wd OS to the ECM and TCM? Would it be beneficial to send it out? If so are there any suggestions on who or we’re to send it?
Thanks.

[ScottR65]

Thought I would report back as to how this turned out. As luck and a lot of research on the web would have it. The short shifting tranny has finally been solved! "Hallelujah"
After a long winter and a longer spring! Finaly I was able to pull the Nova out of its winter nap and see if I could fix the problem. I was able to narrow it down to if the car was scanned by HP tuners and then the scan was stopped it would snap out of its funk and the transmission would act right for that key cycle "Weird"! Restart and it would revert back to short shifting.
A thread on these forums by truckfan2 also had the same transmission issue with a swap he did. Thank God I found it!
Ghuggins is right! There most definitely is a difference in 2wd and 4wd OS for the Gen IV application. There have been quite a few people that have told me there the same. Au Contraire Mon Fre're
So I did a segment swap from a 08 Chevy 2wd and "Viola" it works like a charm. Just as suggested!
I've read though so many threads that never end up with the person following up on whether they figured out the problems. Hopefully this will help someone in the future.
Thanks to all that posted! Much appreciated!

[kjnman]

So I did a segment swap from a 08 Chevy 2wd and "Viola" it works like a charm. Just as suggested!

You just reprogrammed the TCM for 2wd ? or you had to seg swap the 2wd system OS in ecu ?