new boat here.. twin 305 merc. just put in 2 new batteries and still reading low voltage on the gps with both battery switches on it reads 9v with just one switch on it reads 10 ............any ideas?
Check the voltage at the batts. with a volt gauge. If 12 then check it at the GPS end of the wire. If 12 check the ground, if good, replace the GPS, if less replace the wire.