[m1782t]

Well guys after some severe medical setbacks, I'm back to this project. I put it on an analyzer after sitting inside over night, the water temp sensor said 62 the new mat said 242 and when the mat was unplugged it said 306. I had tested the old mat and it was right where it was supposed to be at -10, 70, 210, but I replaced it anyway. This left only the wiring and the pcm. Since wires don't get better than new when they fail, I replaced the pcm, no help. I unplugged the mat and clipped a 100k resistor to the leads, so it would think it was -40, still no help. It still thinks the engine is always warm. Can the prom on the pcm loose it's settings and can a new one be purchased, or the old one tested or reprogrammed. Is it worth a try to put the one in from the replacement pcm which came off of an 89 Calais? Or is there something else that would make the pcm think the mat is always hot? thanks