0411 swapped 7.4L 4L80E 4WD Low Stuck In First

[99k2500]

Truck runs through the gears in 4WD high but not low. Stays in first. Another problem is it shifts in 2WD as I wish and then the TCC locks which is what I want. I let off throttle and it unlocks but will not relock.....??? I will post a tune tomorrow if anyone is interested in helping!

Thanks!

[99k2500]

trans change PE change Idle change1.hpt

[99k2500]

I have options to change values in 4wd low and high. I do not get any shifting in 4wd low.... Am I missing something? I don't think I have a 2wd trans tune, do I?

[Erik Dicus]

i would monitor speed in 4lo and check compared to commanded table. commanded seems kinda high.

as for lockup , your file unlocks anything less than 50. i got a stock file from repository, i think it was 35. dont have a log file so not sure what speeds we are talking

[Erik Dicus]

also any kind of misfire will hold tcc off generally

[99k2500]

would all stock files with a 4L80E trans be the same numbers? That way I can copy and paste it over

[Erik Dicus]

I dont think so, going to be different depending on gear package. have you tried the bluecat trans calculator?