I wanted to change my gauges from black to white and did so but now the tachometer si way off. I noticed that when I put the tach at zero and plugged in the plug it dropped below zero. So then I left it plugged i and changed it to zero. It worked fine while driving. Later, When I went to go leave in my truck the tach was back below zero?????? I don't get wtf is going on...If anyone could help it would be appreciated