I have a error code of F450 FMI 4. Coolant temp. I have already ruled out that the tractor is not overheating. I have replaced the temperature sensor already. The tractor ran fine for a day and the next morning same thing happened. Gauge shoots all the way up and then down completely. Hooked back up to scanner and had error 450 FMI 4. With the tractor plugged into the scanner I can see the voltage reading 0 and 413 degrees gauge still pegged to the left. When I unplugged the sensor my voltage increased to around 2.15v. I tapped on ECU and voltage increase to around 3.8v and a little more tapping it jumped to 4.9v: Tapped a little more and voltage started to decrease slowly down to around 1v. I tried tapping on the ECU with the sensor connected but did not see a rise in voltage or the gauge move. I have already checked the harness for grounds and shorts all checked good. I did however have a fuel leak prior to this and the controller plugs did have fuel in them. I clean the connections to no avail. There was no swelling to the ECU or corrosion to the pins. I am leaning towards a bad ECU at this point. But before I spend the money for a new ECU I wanted to know if there was anything else I could try.
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