Originally Posted by
littlesister
This is a follow up on a problem I was having with my HDS 12s loosing GPS signal. 22ft aluminum Bay Boat. HDS 12 live at console. HDS 12 live with AT2 up front. Sitting in my drive way I had a great signal on both units. 5 or 6 bars on the satellite page. Cut the ignition key on and they started dropping like fly's until the no GPS warning would pop up. Turn ignition off back came the satellites. This drove me crazy all winter. GPS would actually lock in sometimes when out on the water. Would come and go. I tried everything "I Thought". All my electronics run off a dedicated battery. HDS 12s. Point 1. AT2 and separate charger. Completely isolated from the rest of the boat. I thought! While cleaning out the compartment where my AT module is mounted I noticed I had grounded the AT module to the boat. Well, being a aluminum boat the boat is also common ground to the cranking/house battery. Removed ground GPS problem solved. Cut ignition off and on with no effect on satellites lock in. 90% of electrical problems on boats are usually ground related. These two grounds were interacting when the ignition was on. Why they effected my GPS signal. I still don't know!
