I know this topic has been widely discussed..but everyone seems to have a different issue..I was stuck in snow...tried going forward, then back, then forward again...etc. I wasn’t pushing it hard..just trying to get out of my driveway...When I shifted from D to R and back....I let the engine idle down then shifted, so no back and forth really quickly...Suddenly I got a red warning saying “Cool Transmission before catastrophic failure”..or close to that...I immediately stopped, checked the fluid...it need about 1/5th of a quart...not much..Sfter an hour my Avalanche, which is automatic, will shift into Every position...but only Park and Neutral are working...I’ve been dead in the snow ever since..I know a little about autos...change brakes, replace brake lines...fairly easy stuff..I didn’t hear any noise, there was no odors...I maintain my vehicles on my own, which include adding fluids to the front and rear differentials and transfer case, change the oil about every 4-7K using Mobile One Extended performance 5W-30 15,000 mile High Milage oil and Mobile One Extended performance 1 year or 20k miles filter, I check everything and log it..But now I’m in this predicament...I’m now on Disability, and own a home...so that was a huge pay cut..I live hand to mouth...and I bought a CarShield Extended Warranty...But they won’t honor it because it happened 8 days after the initial 20 day/500 mile waiting period...But I don’t have any maintenance receipts because I bought a ton of oil and filters and lube a year to a year and a half ago when there were a lot of good sales...So my garage is/was pretty stocked...but I didn’t save the receipts from 1.5 years ago, because I wasn’t planning to get a warranty then...So if ANYONE has any insight, that might be valuable and save money because most places around here just say...Bad Tranny, we don’t fix them we replace them...but I did find a shop that does fix them..they have all the certifications and years experience...SO PLEASE...PLEASE HELP, I’m an Engineer so I pick up on things fairly quickly. THANK YOU, in Advance
*And FYI...stay AWAY from Carshield...they first off, started saying that I told them it happened on a date, that was within the trial period...They day they record their calls..So I said Prove it...and the date was just the day I got home from a holiday trip..So I put the 500 miles on...Then I told them I actually didn’t get home on that particular day but actually 2 am the next day...So they changed it..Enough about them...Just Stay away...They’re rated an “F” by the BBB...Sorry about that...I just get fired up talking about it...ID REALLY APPRECIATE ANY INSIGHT...Thanks Again!
Craig

 

Yes those warranties are scams. I've wasted money on those too. Sorry you had to learn the hard way.

Unfortunately automatic transmissions are pretty complex beasts. Thousands of moving parts. The only thing shade-tree mechanics can do is replace/top up the fluid, and change filter in the pan. Maybe change some solenoids if you're brave. You could also inspect the shift linkage and make sure electrical connectors are snug, but judging by the vintage of your vehicle, it's probably got some miles on it. The tranny has probably given out. If you've got a pressure gauge, you could try hooking it up to the pressure port to make sure the pump works.

It's not economical to repair trannies. The moment you need to work on the gears/clutches/hydraulics, the tranny has to come out of the vehicle, go on a bench, and get torn down and rebuilt. You could pay the hours it would take for someone to diagnose the problem, but it's far cheaper (for you) to have them take a finished one off the shelf and plunk it in.

What model of transmission is it?

 

maybe this will give some satisfaction to your engineer side