I had a WTEC II that went to "Do not shift" on the dash when I went to put it in gear. It occurred after driving for about 20 minutes with the air conditioner on, which had a vent that was blowing down on my feet right over the transmission shift ECM unit. I was able to get back home by applying heat to the case (actually heated it with hair dryer periodically). Coming from a background of electronic engineering and repair, I took the cover off the unit, heated it until it worked, and using air guster I started chilling the board in different places until it acted up again, which can be done while powered up. I found a faulty solder joint in the middle of the circuit board just under the main cover. Once it would fail, I would heat the circuit board back up and pin point the cold spray further until I found the specific component/solder joint that had failed. Once the cold hits the bad solder joint, it shuts down. If yours doesn't shut down when chilled, you are probably facing a different issue than I had, but from what I read, this is a very common problem and sounds like a manufacturing problem that affected most of these units. Some salvage yards want $2000 for these things and no guarantee. If you don't know what you are doing, send it off, but if you have a little spirit and have done this kind of stuff before you will save some money, no re calibration necessary, maybe even continue your trip in a couple of hours. After I had soldered one of these two resistors (see http://www.soarkansas.org/wtec.solder.jpg, outlined in red), I could no longer get the cold spray to shut the unit down and it has been working without trouble for almost a year now. I even went out during the dead cold of winter to test it and smiled each time it worked. Don't even have to remove the board from the unit, just take the metal cover off and check it out. If you decide to solder, make sure you have a quality fine point tip gun. You will have to use your fingernail to scrap back some of the rubbery protectant stuff they applied. Also, these are surface mounted resistors and you need a 3rd hand to hold the resistor in place while re-soldering because the other end of the tiny resistor will de-solder as well and it will be a full fledged resistor soldering rodeo.