4L60E shift tables/4wd low range speed calculation

I'm running a 4l60e is my s10. does anyone know what tables are used when? say if I have it in d2 what table tells it to shift from 1st to 2nd? Also how does the pcm calculate the speed when in 4lo? looking at my logs it shows that it is shifting at speeds below what is in the normal shift table. when driving in 2hi the shifts are pretty much in sync with the tables, so I'm a little lost as to why its a little screwy when in 4lo. the vssb/drac has been recalibrated to account for the change in gears and tire size. Is there something else I need to do to account for it being in 4lo, or is there a change I need to make in the ADX for it to calculate speed properly when in low range? I've looked at 4wd Low Reduction Ratio at Location: 5D16, 5D17 , and RPM/VSS Ratio at Location: 5D18, 5D19. what are these ratio's of and what do they do? there is not much differnce numerically between the two settings. I thought for sure I'd find something on this at FSC but my search didn't turn anything up.

The "Normal Mode Shift Tables" are used for most driving, for WOT use the "Kickdown Mode Shift Thresholds". In kickdown mode both RPM and MPH qualifiers must be meet for shift to occur.

The "RPM/VSS Ratio" and "4wd Low Reduction Ratio" calibrate the bin for tire size and gear ratio. From what you described, the 4wd Low ratio needs some adjustment.

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Originally Posted by 93V8S10

the 4wd Low ratio needs some adjustment.

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that is what I was kind of thinking but kind of drawing a blank where to start. guess its going to be trial and error.

There is a equation for this in the xdf item comments, that should get you close.

EDIT: Well I thought there was. The equation is under "RPM/VSS Ratio", you will need to reduce the "numeral gear ratio" to reflect the actual gear ratio in 4wd low.

With all these options in this bin can you make the adjustments needed for gear and tire change with out changing the DRAC/VSSB?

In the LT1 you make changes needed for tire and gear in PCM, no DRAC/VSSB.

If not then all settings should already be done if you modified DRAC/VSSB? Unless bin was for differant ratio transfer case...

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Originally Posted by EagleMark

If not then all settings should already be done if you modified DRAC/VSSB? Unless bin was for differant ratio transfer case...

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that is what I was thinking, since I already made modifications to the DRAC/VSSB i assumed it would be acurate in 4lo also. I'm still runing the factory transfercase that came with the truck.

No, all three things will need to be correct.
1. DRAC/VSSB
2. RPM/VSS Ratio
3. 4wd Low Reduction Ratio