I have a 97 classic, with a 60 series detroit. I hit a bump the other day, and the temperature gauge suddenly spiked setting off the temp buzzer. The truck is definately not overheating, even though the gauge says it is. I have tried disconnecting the sensors with no change. The gauge spikes immediately upon turning the key to run even after the truck has sat for several days turned off. Also the tach, intermittently stops working, and I think the fan clutch is staying engaged all the time, even with the switch set to auto. Can anybody help me??