Temp Gauge not responding
 

My Dash Temperature Gauge is not moving after startup (it stays at the bottom). I have checked my fuses and I don't know of anything else electrical that is malfunctioning.

Any suggestions on what I should check? In the meantime, how can I ensure that the thermostat is doing what it should and not causing overheating by not pumping coolant, etc?

The car does not seem to be overheating now. I have driven it as long as an hour this weekend and the engine seems to be normal.

It could be the Sensor is dead or the Wire is disconnected from the sensor.

I have never read up on how to test the Coolant Temp Sensor; to see if it is the Gauge or the Sensor. Someone who knows will have to chime in on that.

Coolant temp gauge Sensor
 

Applies "Ground" to Wire Based on Temperature.

If you Ground the Wire @ the Block Independent of the Sensor the Gauge should
Max Out.

Pull the sensor wire off the sensor in the and clean both really well. I had some problems with my temp gauge reading too low, and being odd. The sensor connection was all corroded.

I just changed my Glow Plugs and converted my Relay to a manual push button one. Does anyone know if the Original Glow Plug relay supplies power or something to the in dash temp gauge?

Was your original Glow Plug Relay connected to a Temp Sensor?

The old 123's have two sensors one for the temp gauge and one for the GPs. Yours only has one sensor, is your temp gauge working? If it's not then the signal wire from the sensor was passing through the relay and you need to connect the sensor wire to the wire that was coming out of the relay and going to the gauge(wired in series). It's possible that the relay and gauge are wire in parallel so that they are both getting the signal from the sensor.