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View Full Version : Help with TCM Tune.



WisconsinHick1
July 16th, 2012, 07:56 AM
I am a truck puller and I am wanting to have my truck start in 3rd gear and shift into 4th while Im in 4low T/H on. How does the TCM determine what table to look at I see there is one for low range and tow/haul but I don't see a table to 4low T/H. Would I just be adjusting the low range shifts?

Thanks for all the help guys! :beer:

THEFERMANATOR
July 17th, 2012, 09:26 AM
From what I found, 4 low doesn't use the tow/haul feature, just the 4 low shift table. Also myself and many others have found that the 4 low and tow/haul tables are mismarked and backwards.

WisconsinHick1
July 17th, 2012, 11:39 AM
So T/H is 4lo and 4lo is T/H?

anarchydiesel
July 17th, 2012, 11:59 AM
never built a tune to leave in 3rd then shift to 4th, but If you set your 1-2, 2-3 upshift speeds to 0 for all modes then it should go to 3rd on the line and then shift to 4th going down the track. Set your 4-5 upshift speed to 150mph so that it does not go into OD. We usually leave in 2nd and shift to 3rd, but that is with a workstock/hotstreet truck.

WisconsinHick1
July 17th, 2012, 12:18 PM
This is for a 2.6 truck that spins the RPMs in 3rd. I have a feeling I can hold 4th no problem.

05chevy
July 18th, 2012, 10:58 PM
I always leave the 1st table (table A) alone for you can still drive around using 1st gear. Then I change the rest of the tables for when you hit t/h, 4h or 4lo it deletes 1st and 2nd if you want it to

WisconsinHick1
August 2nd, 2012, 10:51 AM
Well Im still having an issue with my truck going in to OD when in drive.

Can someone take a look and see if Im missing anything?

13647

Big Mike
August 2nd, 2012, 11:56 AM
Try changing all the tables (except the "normal" table) to what you want to accomplish, not just the hot and 4Lo patterns as the columns are sometimes mis-labeled in certain OS. They're mis-labeled for mine I know.

WisconsinHick1
August 2nd, 2012, 01:12 PM
Big Mike do you or does anyone know if T/H really change anything when the truck is in 4low?

Big Mike
August 2nd, 2012, 01:32 PM
As I understand it the 4Lo tables override any/all T/H tables for both shifting as well as TCC apply/release. So in 4Lo it's using the 4Lo tables regardless of whether T/H is also activated or not.

WisconsinHick1
August 2nd, 2012, 01:59 PM
Man that would be great because then I would worry about other tables. Maybe I'll change one table at a time to pin point which one is 4low and just make the adjustment to that one.