Hi All,
I did a major overhaul of my cooling system last Fall. New rad (nissen) new thermostat and finally a temp gauge bypass.

All has been great, until Saturday in the midst of the storm I stopped for gas. When I restarted I noticed the temp gauge needle sitting at the bottom (off the charts as it were) a couple of well placed smacks to the top of the dashboard have neither revived or frightened the gauge into communicating.

So, my question is:
how do I ensure that the problem is with the gauge and not some other link in the system (car has a belly pan, no apparent loose wires etc.)?

If I need another gauge, how do I test it to make sure it functions properly (I will bypass again if I need another gauge).

Thanks as always in advance

Rod