The reason for the failure could be a failure in the connection or the gauge itself. Alternatively, the temperature sensor could have failed.
Loose connector, wire grounding out, bad sensor.
210 deg F, it should be directly verical on the engine temp gauge.
low coolant and/or radiator leak or maby a bad temp sensor low coolant and/or radiator leak or maby a bad temp sensor
i change the thermostat and the temp switch but still not working
195-220 195-220
If your temperature gauge isn't working the problem is a bad gauge, grounded or disconnected wiring or, most likely, the temp sender isn't working.
On my 1999 Jeep Wrangler the batt. temp sensor is underneath the battery and mounted to the batt. base plate through a hole in the plate.
Located directy below the driver's seat! :)
probably the sensor
Check your grounding on your temp sending unit.
You did not say if 4 or 6 cylinder. But the thermostat is supposed to control the temp by when it opens to allow coolant to flow. I think stock was 195 degree F and that is what I have in my 1991 4.0L and the gauge registers around that.