Should be a switch next to it, if you have a 24 volt troller it will show voltage of each battery by pushing the switch up or down, it only shows it when the switch is being pushed it doesnt show it constantly. This is how it should work… but no promises that over the last twenty years somebody didnt disconnect it or hook it up wrong. PM me your email and I will take a quick video for you of how it works on my 94 Eyra if you cant figure it out. Hope that helps