bATTERY mETER

Hello, I have a 36v powabike (uk) the problem I have is that the led meter always shows full charge no matter how much I use the bike. I know the key switch has been changed and I was wondering if a wire has been connected wrongly, are the led meters polarity concious, or is it likely to be a fault on the meter board. Sorry I don't have any more information for you to go on, it's more a hope that you can start me off in the right direction. Thanks John