Check to make sure the module has power to it.
Is this a new install, or did it recently just go out?
I had this issue a few years ago shortly after a professional install. There was a Lowrance service bulletin about making sure the module has direct power from the battery and not just from the dash power strip.
Auburn Sports and Marine knows all the ins and outs of Lowrance, maybe give the service department a call.
mine did that durring the disco bay derby i took out my navionics chip and put my nautic path chip back in and it worked fine. I have a global map 3500c and it really doesn't like the navionics chip too much. It works but seems to be really slow. This may not be the problem but it solved my problems durring that weekend.
I have had nothing but problems with my Lowerance, I have sent them back to the factory and had them serviced and they were brand new out of the box, Paid for them and they sent them back pluged them in and still don't work.
Now they want me to pay for them agian and i have never even got to use them. sick:
I have not had this problem with my Lowrance but do have it with my Humminbird. I think it may have something to do with heat. I only have the problem when the sun shines through the windshield onto the GPS antenna on warm days. I have tried shading it with a hat and that seems to help some. I have been meaning to put the module outside and see if that helps.
I have had the same "gps mudule not responding" problem with my Globalmmap 3500. It has always began working again after a few minutes but it is now happening more often. My X107DF sonar just crapped out too and I am trying to get an authorization number to send it into Lowrance.
I have had the same thing happen and I found out that the connectors arn't making good connection. I would disconnect the plug at the GPS head and reconnect it and all was fine. Is your GPS head a 2000 or a 3000. The one I had for my LCX-15 had this problem it was non NEMA 2000 network. I have had no problems with my new LCX-113C it uses the 3000 GPS head.
Good luck finding your problem