shift kit question

[2500Ak]

4L60E Manual Mode Downshifting 3-2 & 2-1 - EFILive Forum

I think that about solves it.

There seem to be singular speed values that the PCM will not allow the column actuated, manual downshift to occur at.

namely

2-1 Manual 44 MPH {D0928}
2-1 WOT 42 MPH

3-2 Manual 0 MPH {D0933}
3-2 WOT 90 MPH

You said you were at about 40? Lets say that as you punched it, it achieved a little over 40 as it was trying to shift.

It invalidated the parameters, but the gearcommand made it shift anyways. What one might think of as an uncertain shift, not sure whether to follow the manual valves command, or the solenoid.

I was wrong RPM has no barring on it, its based on speed alone.



I'd really like to see the effect of modifying those values to give a gear command like effect, in addition to a gearcommand equipped transmission.


This is still all very hypothetical of course.


Edit:Wait a moment I've got that mixed up. Let me look at this again.

Okay the 40 was addressing the 2-1 shift. So I don't know, it's still worth a try.

The number appears to indicate the speed below which it can shift, which makes little enough sense for the second parameters.

Perhaps the downshift is a mechanical function even without gear command, the solenoid isn't necessary. But that doesn't explain how it waits until the truck is under 62 mph in stock trim...



Or maybe its that it won't immediately hit second at part throttle, and that you must apply WOT to force it to downshift for one reason or another.

I think that might be it, if you put it into 2nd and floor it, it should drop into 2nd.

If you put the selector in 2nd it might wait until you floor it to engage.

So lets say you put it in 2nd, the gearcommand makes it go into second, then it bounces back because the PCM tells (which is shouldn't be able to do but these SK's were made for older transmissions so who knows) it too then it plunges into 2nd when you floor it.