Weird Temp Gauge

[Private Nemo]

I have prob with stb temp gauge . Turn the key on and it reads 145. Engine ice cold. New gauge, temp sender. Switch gauge with port side gauge same thing. Port side reads fine on port side. If I piggie back another gauge onto prob gauge via alligator clips , they both zero out. What gives. ?

 

[bruceb58]

Re: Weird Temp Gauge

If I piggie back another gauge onto prob gauge via alligator clips , they both zero out. What gives. ?

You may have a bad ground on the one that is reading high. Its either a bad ground at the gauge or bad ground at the sender. You can test by using your alligator clips to a good ground.

Another less likely case is a resistive connection to power but I would try the grounds first.