I have an interesting one that maybe some of you have seen before. 01 GMC Sierra 2500 HD 8.1L with Allison 1000 5 spd. Intermittent temp gauge readings. Usually only as transmission is warming up. One morning I started the vehicle and within 10 seconds the warning came up that said Trans Temp Hot / Idle Engine. Other times it does the same as I drive about 2 miles from home in the morning. If I let trans warm up then shut off engine and start again sometimes it will register normal and other times the gauge will not register. As this happens I will sometimes get an MIL and code 7000 & 7012. Seems like a bad connection somewhere or bad temp sensor. Where is the temp sensor? I unplugged the 20 pin main wire harness from the back of the transmission and there was oil in the connectors. I did the best I could to clean everything up and put it back together. I will see if this solves the problem.