So pretty much ever since I put my new motor in with the Trailblazer TC my truck has had an issue staying in lock-up on the freeway (went in and out intermittently). Over the last two days the problem went from bad to worse after my truck was on the dyno. It will drive fine and then when I go to get on a highway (more than 50 mph) the TC wont lock up at all, not even once. Eventually it spits up the code p0894 (Transmission Component slipping). After slowing from highway speeds it has a very hard 1-2 shift, but the rest of the shifts are normal (Ive been told this is because the computer increases the line pressure). I told my tuner about the problem at the dyno before it started not locking up at all. With the truck running at highway speed on the dyno he said when he commanded it to he could get it to lock up fine.

Codes I've gotten these last three days:
-Transmission Component Slipping (6 times, 2 times a day, seemed to be in pairs)
-Random Misfire (Once)

TrailBlazer I-6 Torque Converter has 5k on it.
4L60E Transmission has 20k on a rebuild with shift kit

What could be the cause?

Thanks for any help

 

Is it possible that my TC is toast even tho the tuner can lock it up but using his computer?

 

Maybe the higher stall of the converter is fooling the PCM into thinking that that trans is slipping? I had a similar issue after my trans/converter install, but it was a different code (can't remember which code exactly). I believe that your tuner should be able to work around that code...the smaller, lighter converter could account for a misfire also as the crankshaft will be moving at a different speed than the PCM is tuned for. If it isn't actually misfiring, you may have to have your tuner soften up the misfire counter...

 

I had this issue before - oring on the input shaft was damaged.