To help get you started.
http://www.irv2.com/forums/f22/2002-...ded-88438.html
I certainly would not want to guess at the problem especially at those prices you mention .... to be quite frank, your tech has not proved this out IMO ....not that he's wrong....I'm just saying that I would dig a little deeper to check this out and would like a wiring schematic of the TCM unplugged it and with a jumper with a 10qmp fuse hook to the power terminal and the ground circuit. I would want to prove out that the TCM was indeed shorted internally. ( and if so it's most likely a diode)
An important side note. Some of the best advice I ever received here at iRV2 was using the " iRV2 GOOGLE" search function located at the top right of your iRV2 screen.
ps' I see a reman TCM for $550.00 and the rebuilder can bring you up to any programming if necessary.
Happy Hunting