I bought a 2000 4.2 V8 Quattro from an auction and the car only has reverse no forward Drive works on the car. there was water underneath the passenger floorboard the transmission pan had no chunks of metal no smell of burnt anything. I brought the car to a German car specialist after trying a bunch of things and he says my transmission is blown I have no confidence in him. All the lights for the different gears on the dashed are lit up,
He told me my transmission was blown before even checking the electrical I'm taking the car back and going to fix it myself. If I put the car in reverse it works fine, but as soon as I switch it to forward it barely moves it all and from what I read that what they call limp mode. Fluid temperatures are perfect fluid levels are perfect I replaced the gasket and filter and have it topped up. I am ordering a new TCM what's the steps I need to do when I install the new thing to reset everything and fix my cars brain???

 

I'd try the new TCM. If that doesn't fix it, it probably is the trans itself.

 

It's at the shop now and they want 300 bucks to pressure test the transmission. If that passes I have to spend the money on a new tcm anyways. It's 8500 pennies to get it towed ... again....I've been working on these cars 4 days and I trust myself more then this shop.
What do you have to do to re program the tcm... just use my code reader to delete the codes, plug it in and drive away essentially?

 

You cannot reprogram the TCM with out special dealer equipment. The TCM/TCU should match the transmission code though. If it matches the one you have, there should be no need for any additional "programming". Disconnect the battery when swapping it out. This will also clear any codes and crap data that may be living in the ECU.