Temp Gauge not working

[Shims]

Replaced the coolant temp sensor, still nothing. Installed a mechanical gauge and it seems to only move after I turn the engine off. This one really has me stumped. It's an 87 W150 with the 318.

First time posting, I bought the truck over the winter just to tinker with.

 

[crazzywolfie]

have you tried grounding the wire that runs to the temp sensor and watching what the stock gauge does?

 

[Shims]

Not yet, I'll try that next. thanks!