2006 Chevy van with a 4.8 auto.

The tranny feels like the converter is slipping badly. The truck has 25,000K on it.

It has a "towing" button on the dash, when the tranny slips the worst it seems to work like it should. When the tranny feels like the converter is slipping as it usually does it doesn't seem to do anything, button in or out.

I do NOT tow with it, and I already checked the fluid, the level is up but it doesn't smell like I'm used to. Doesn't smell "right", but doesn't smell "burnt" either.

Is there any techs here? I'm looking for any possible TSB's etc...

Well, one of the biggest things is that whomever had the vehicle before you got ahold of it towed without it in "tow/haul" mode. When the transmission is placed into that mode, it keeps the torque converter from locking up, thereby allowing the transmission to withstand the extra rigors of towing. If its not put into "tow/haul", the converter will lock up like normal and you'll burn the tranmission to the ground that away. The smell you've probably got is somewhat burnt fluid. Normally transmission fluid smells anyway, but as its burnt up, the smell gets worse. Only real thing you can do is pull the trans and have it rebuilt. You could try various "stop slip" additives, but you're really only delaying the inevitable.

my 99 monte doesn't lock once in a while... i think it's related to my misfires the car has once in a while and rough idle associated with it... but it has unlocked a few times under cruise at 70which is kinda odd.

Ah, isn't there warranty on this piece anyway?

Ah, isn't there warranty on this piece anyway?

Yup, it was bought new, so warranty will cover it.

Nobody towed with the truck, the bumper even states no towing, but it's never even had a hitch!

Hard to make an appointment because it's being used for work, and a loaner isn't a great option. Should go in soon though, I'm trying to find any info I can before it goes in, I had a GM tech in it, he says something is funny too.

I'll keep it updated once I find out!

The service manager was awesome! He let me know I have a "faulty transmission assembly".

LOL!!!!!

I will get a new tranny and converter, I asked what parts actually went bad, he said when the tranny gets in and I can make an appointment to get it swapped out he "should" be able to tell me what went wrong, but I talked to two of the mechanics and I have a feeling the tranny won't even be opened up...

More waiting!

Very doubtful they'll crack it open. More likely than not, they'll swap the transmission, give you a bill, and call it a day.