I need to have Allison TCM updated at dealer, how do I proceed with tuning data? O/D

[Manic Mechanic]

Thanks for some guidance here. I have a 2001 Silverado 2500 HD with the L18 8.1 gas engine and Allison 5-speed. I have installed a GM O/D lock-out switch kit (the 01-02 models didn't have this factory) and to enable it to function one has to have the TCM programmed to accept the new input and it's function.

What I don't know is if this will erase my tune and if so will HPTuners software have a problem reprogramming the TCM afterwards without using any more credits.

If the tune for gear ratio, shift points, speedo etc. is replaced do I need to download the new TCM update with the O/D switch enabled and transfer my changes to it or can I just download my changes onto the TCM as is when I pick up my truck from the dealer service dept.?

Will the dealer update just upload my current file add the switch function and download it without any other changes?

Thanks,
Vernon

[charcoal03silvy]

I wonder if you can have a segment swap done to enable it?

[Manic Mechanic]

I wonder if you can have a segment swap done to enable it?

At one time there was a TCM tune posted on DieselPlace.com that had the switch enabled. I'm really not good enough at this yet to know how to do a segment swap either.

Vernon

[charcoal03silvy]

You would need to email support about it

[Manic Mechanic]

I found and answer to the license question here: http://www.hptuners.com/forum/showthread.php?30254

But I still don't know if the dealer will keep my current tuning with just an addition or flash in a stock tune with the additional lockout function. Since I have nothing but time and frustration to loose I'll just get it done and find out. Will report for future reference.

Vernon

[Manic Mechanic]

The dealer TCM re-flash with O/D lock-out enabled replaced everything for the trans with the stock tune again. It took a few sessions to change some things back where I want them. The ECM was unaffected.

As far as the O/D lock-out button, it didn't cost me anything but a little time to do this but for an 8.1 with 4.56's it's more of a novelty. I have but rarely tow anything heavy enough to need it with 4.56's. I would think 12K or more for it to be really utilized. Now if I still had the OEM 3.73's and or travelled through mountainous areas it would be more useful. It should help with dyno tuning.

Vernon