I was once driving a '63 Kenworth that would overheat when the headlights were on. The extra load on the alternator was causing the water pump belt to slip. It had a Cummins engine where the alternator was driven off the waterpump. Tightened the waterpump belt and no more problem. Worth a look. Check your belt(s).I have a 5075e. I noticed that the temperature gauge starts rising into the red when I turn on my lights or turn ac blower on high. Any ideas what causing this?
Sounds like a ground issue. How old is the tractor? Had one a couple of years ago that the ground was loose under left rear side of cab. Also check the one under right side of cab on the side of transmission case. Seems like we had one that only showed hot when pto was turned on. If grounds are all tight, take them loose and clean paint and rust from frame and wire and then tighten them back up.I have the same tractor, but not the issue. It sounds like a gauge ground issue.