Temp Gauge Issue

I have a 92 XJ that sat for 2 months in my garage. I started it up this past week and with a jump it ran quite well. The only issue I have is the temp gauge is not registering. When it cranks to start the gauge needles goes to one side and then back to zero. I have replaced the coolant temp unit thinking that was the issue and that did nothing. I traced the wires for the back of the gauge to the coolant temp sending unit and everything is in tack.

Im stumped. Thoughts???

I believe the dash voltage regulator goes through the temp gauge but I'm not 100% sure