There is a glitch in User 2 program in the 3-button Bartlett. Normally, there is no segment 4 in User 2, but there can be if you program it in, and if there is, and if it is a cooling segment that goes on for more than one hour, the TC-- code will appear and shut down the program. Normally TC-- means the TC is wired in backwards, so if the kiln has ran fine before and no one just changed or messed with the TC, start checking the User 2 program for a long cooldown in segment 4. The way to deal with it if it is programming is easy. Make segment 4 just drop a couple degrees, then add another segment as segment 5 to take it from there down the rest of the way.