I have a simple question,I have my sonar hooked up to my gps,which is in turn hardwired to my marine radio.Is like this in order to get the co-ordinates from the gps into the radio,if needed in an emergency.Problem is, when i trun on my Garmin gps,the sonar stops working,just flashes a 2ft depth when in reality we are in 78ft.I turn off the gps and the sonar comes to life again,any simple solution or ideas ?