Hello. I have one concern about my temp gauge. When truck is off, temp gauge needle either stays where it should stay on 0 or showing me the normal temp of the engine (around 150-170F) When the ignition is in on position, needle goes back all the way down to the left (below 0F). I have tried to swap connection wires to get different polarity. However, the needle is going all the way backward or forward. There are three wires (red, white, black). Three connections on the gauge ( one says G, another I, and the third one is ...I forgot) I already changed the sending unit. Wasn't the case. Then I changed the gauge itself. Problem stays. I don't know what to do next. Any suggestions? Thank you