temp gauge pegged hot

[blue72k10]

I have to agree that the harness looks like that TCS stuff. Would that harness have any effect on my voltage issue? My truck has an HEI that was wired by a shop from a guy who worked for me that I have total confidence in his ability to do stuff correctly. I will pull that harness out, put it with the other spare parts, and put aside for the next owner when it's time. Is there a proper way to wire up and HEI and from that TCS article that man used that pink wire in that harness for his HEI power. My setup works but if there's a better way maybe I should look at it now that I'm in this deep. Thoughts?