Having odd TCC lockup issues all the sudden - trying to understand TCC lockup tables

[Philip Parker]

Hi there - for the last month or so I've been experiencing some odd TCC lockup issues with my 7.4/4L80e setup. This all started to happen after changing out the trans fluid, and it seems the tune is directing the TCC to engage in 2nd gear and at light throttle.

Am I reading this correctly?

Philip

Edit - also what determines the normal/economy/cruise modes in the apply/release dialog?

[Mikeloko]

its not commanding to lock on 2nd until you go over 87% throttle position , on 3rd and 4th it is commanding to lock up at light throttle position

[twenglish1]

Is it in economy mode? Im not sure what controls this, if there is a button to toggle it on or off? This would explain the low speed, low throttle TCC lockup occurring. Look at the Lockup speeds/throttle position for 2nd gear. Need to post a log, TCC channels, speed, rpm, and throttle position at the minimum.

Screenshot 2025-07-30 155532.png

[RDF1]

Do you have a datalog?
IF trans hot has been triggered by a false input it could lock in 2nd at very light throttle.

What codes are you seeing?

[Philip Parker]

That?s what I thought too, and that?s how it?s behaved since I?ve owned the truck, but now it?s locking when hot, and I?m just noticing the different mode tables. I have no mode buttons in this truck.

[Philip Parker]

Yeah this was confusing to me as well. It?s like it switch modes suddenly. Or maybe it?s in hot trans mode and my cooler is fully plugged with stuff?

[Philip Parker]

I will make one - one thing that?s confusing to me is does an added log parameter automatically create a graph in the graph window? Does it matter?

[gtstorey]

A parameter will not create a graph by itself. And your graphs aren’t part of a log file. It is strictly the data that is included. It will load into any graphs that are in use by the scanner that is set up for the channel.

[RDF1]

I dont remember if the old pcm will show you which mode its in. Its worth a shot to see.

[edcmat-l1]

Need to post a data log so ppl can see what it's doing.