E67 and T42 issue with TCC locking VERY BRIEFLY after the 1-2 shift

[Snowman1987]

Hey guys. An odd one for me.

UPDATE 2/18/25. FIXED. RESOLUTION IN POST 8

2009 Colorado 5.3 4L60.

The truck has a cam, headers, and JUST got the trans rebuilt with a 3200 stall, and transgo shift kit. From previous logs ( a couple years ago) it was doing it then, but much more pronounced after the rebuild as I didn't even notice it until now.(retune for trans)

The main issue is the TCC will lock momentarily sometimes after the 1-2 shift. It is easily notable in the scanner and feels horrible. It has also developed a TCC lock up surge no matter the pressure I put on the TCC if you go up a strong hill with moderate throttle.

Attached log and tune. The tune may be not be the EXACT one in the log, as we tried a few things honestly. I also uploaded a log from when the TCC solenoid is disabled it will NOT do it at all. IIRC when I enabled shift lock it didn't do it, but the TCC surge started, so take that with a grain of salt (not sure if that caused the TCC issue or it was there the whole time and thats when we started noticing it....)


Talked to another tuner who has seen the same thing, with no resolution so any help is greatly appreciated!

bhp 9 read plus small back to stock changes.hpttrans issue.hplgood tune no lock up.hpl

[Alvin]

U0101 - Lost Communication with TCM (Current)

You have that code present right now. That's going to be the cause.

[Snowman1987]

It didn't show when I checked. I know you are well versed in the TBSS's etc so I know you have ideas with the E67/T42. I will review again.

Thanks

[blindsquirrel]

'trans issue.hpl' has it, the other one doesn't. Click the 'Details' tab at the bottom of the channels list.

[Snowman1987]

Yeah, know where to find it, just didn't see it. Thanks

So, it is set as factory to Mil on second error... Should I change that? I DID clear codes during logging to no change.

[blindsquirrel]

That code means that the ECM loses the canbus to the TCM. Since it's not in every log all the time, it's intermittent. The trans isn't going to ever work right if half the system goes incommunicado at random. The problem isn't the code being there, it's whatever wiring problem is causing the code.

[Snowman1987]

I'm familiar gwtting the code occasionally writing/reading the E67/T42 deal, but will write, clear, and then check to see if it shows itself again and go from there.

Will update.

Thanks!

[Snowman1987]

UPDATE:

It was the valve body. B&M (the company the trans builder uses for parts) was familiar with the issue to some degree. While I do not know the specifics of the changes they did in the Valvebody, per their instructions he redid it and the issue is gone 100% and drives normally again.

Thank you again for all of the help!

[blindsquirrel]

So it works now, but still has the occasional U0101? Because a valve body can't cause or fix that code.

[Snowman1987]

Honestly, I haven't logged it since the valvebody fix, but the builder and customer say it is doing great.

We are doing some WOT track tuning soon, so I will update with it then as we cruise it around to see what the computer is seeing as well to hopefully help someone in the future!