I have an 89 dodge d100. I have tried 3 different switches from 2 different makers. When you ground out the wire it shows on gauge so we know the wiring is good and the gauge works. Can't figure out what else to try.

 

the stock gauge barely works most of the time. are you sure you are getting the right sensor for the gauge and not the light? also do you know what thermostat you have in it? will likely need a 195*f thermostat in order to make the gauge move.

 

We did put a 195 thermostat in. When we ground the wire that connects to the switch it runs all the way to hot. So we know we have a full range of motion on the dial.

 

In the past, I would get an aftermarket electric temperature gauge. Just swap the sensor for that in and see what happens. If it still doesn't work, install the rest of the gauge.

 

i get that the gauge itself works but even then these gauges don't usually move much. i would 2nd going with a aftermarket gauge if you really must know the engine temp. most gauge are even compatible with the stock sensor if you are confident enough to remove the wire from the gauge connector and hook it to the aftermarket gauge. i know i did that in my 93 to save me some wiring and trying to get at the senor which is more difficult on a 93 with a/c. only reason i even installed aftermarket gauges was so i could run electric fans and keep the engine safe.