380sl temperature gauge short?
 

On my 380sl the temp gauge starts to act up once the car gets to running temperature. One second it indicates 90c then runs to 110c then back down to 90c I have replaced everything (water pump, thermostat, temp sender, vico clutch, raditor) Also the aux fan runs constantly when I start the car. Could this be a short in the wiring, bad temp gauge, or something else. Does anybody have any thoughts on this problem????