No, gauge was dead. Below 160 Fahrenheit. Unresponsive.
Which is a common symptom of low coolant. Upon cooling, cool and reservoir needed about 1 qt of coolant. Maybe less. System hold 3 gallons when full.
Added coolant, ran engine at 2000rpm, turned heater on full blast to move any air out, still no gauge reading, and fans running wild. Cab hotAF. (Summer here yet)
And the A/C turned off message still reporting.
OBD code reader says temperature control module fault.
So, I pulled off the shrouds, went and got a thermostat and TCM, and set about the changes.
Turns out a mouse had chewed the wire that connects to the TCM.
The on board computer interprets an open circuit there with high engine temp, and then works to protect the engine.
Damnable field mice. Harummph!
I relayed this story because perhaps the engine management on the Grenadier is similar in function and logic.
Which is that a fault in that sensor lead tells the computer the vehicle is overheating massively.