HELP.Wiring Lowrance 520c.

I am wiring up my 520c and I thought I had it all connected/wired correctly and I got a “GPS module not responding”. I am running this unit independently; not netwoking with any other units. Anyone had this same issue? Any help would be great. Thanks. Marty

So I take it that unit has an external gps antenna? You need to power the nema cable on the main power cable. That turns on the gps part of the unit. You will want to have that power running through a switch cause even when the unit is off the gps antenna will pull power.

Yep. It has an external puck. So do I wire the nema wires and the main wires together thru a switch? Right now they’re wired independently to the battery, and I forgot to put a switch in the nema line. Could that be the problem?

There is a pretty good diagram of the right way to hook it up in the owners manual. If you don’t have one, look around page 30 of this 520c Owners Manual

You should have a double network T, or two singles. The gps puck goes into one vertical leg, and the connection to the head unit goes in the other one. You need a terminator on each end of the T. There is also a diagram of that in the owners manual. If you don’t have terminators, I don’t think it will work.

I want your main power going to the battery and for the nema it can be from anywhere. It doesnt necessarily have to be through a switch but recommended. Yeah and like mentioned above you need to have the resistor ends on the T connector.

I think that is where my problem is coming from. Not having the terminal ends. I will let everyone know how it goes when I get home to work on the wiring. Thanks again for everyones input. I always struggle when it comes to wiring.

Thank you to all for your input. GPS/Graph is up and running. Without your help i’d still be pulling my hair out.

Was it missing terminators?

Yup. Missing one terminator. Quick, easy fix. Thanks again.