trust the dash gauge.
Light switch or wiring could be iffy but need to check engine temp.
Use ECM scan tool or whatever to read Engine temp.
ECT for ECM has correct Ω at some temps in my Cave, Sensors Quick Ref
or try IR thermometer
or related but IR lools maybe hard to find w/ CCPvirus panic.
K type thermalcouple w/ meter that reads them work too.
cheap electro "meat" or "candy" thermo work too.
Measure temp at base of Tstant tube next to head.
if using small tips for thermocouple etc for reading engine, use a small blob of brake or wheel bearing grease. Both won't run and transfer heat to tip better.
Engine w/ trapped air or crush pipes are good ways to overheat.
See my Cave, Radiator Caps
and rest of section.
------------------Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)The Ogre's Fiero Cave
[This message has been edited by theogre (edited 05-21-2020).]