cruise control shift points.

[shane]

HELP!!
I have tuned up this 2008 Silverado, tunes great, have corrected the speedo as it has larger tyres, and now when the cruise control
is on it downshifts at the slightest incline, its only in cruise, in every other mode you can accelerate quite happily without it downshifting.
I could just leave the speedo out but that's not the correct way. in the software I can adjust every upshift /downshift except cruise control
any ideas??

[THEFERMANATOR]

Leave the TCM alone, problem solved. There is THOUSANDS, YES THOUSANDS of tables that you CANNOT see in the TCM tuning, many of which use the speedo tables. There is no reason to change the speedo settings for bigger tires. It isn't even set correctly for the stock tires that come on it. If you want to change shift points, go ahead, but if you want everything to function correctly, leave the speedo settings stock.

[shane]

I agree , unfortunately here in Australia , speed detection is a major source of revenue for our government, and a speedo that reads under by 10kph isn't ideal, even with the trans file left stock as soon as I change the speedo cal in the engine tune file (H0136) to correct it , it upsets the cruise control. But it only upsets cruise no other shifts!!! ideally I would like to change the dashboard cal but I cant .I would like to just leave it stock , but would be nice to find a way around it.

[joecar]

I don't see any CC shift tables in your tune file.

[shane]

that's the problem , there is no CC shift tables, I can correct all the shift points bar the one that is the worst :(

[THEFERMANATOR]

Leave the trans file alone. Correct the speedo in the ECM. I've corrected several now and had no issues, so I don't see why you would be either. The cruise works the shift points differently than it does when you're driving it by the pedal. It's part of the algorythim the ECM uses to maintain speed while in cruise so the driver doesn't have to intervene.

[shane]

I have tried to correct in both the engine file and in the Trans file no matter what I try it upsets the cruise downshift points .
Ideally I need to just change what the speedo sees rather than what the Trans sees but no matter what the combination it only makes it worse :/

[THEFERMANATOR]

Changing the ECM should only affect the speedo as the TCM actually reads the speed sensors, and then sends the signal to the ECM. Welcome to LMM tuning.

[shane]

I'm thinking that the cruise module sees the speedo numbers as it only seems to affect the cruise shift points :/

[DURAtotheMAX]

I'm thinking that the cruise module sees the speedo numbers as it only seems to affect the cruise shift points :/

There is no "cruise module".....