perplexing electrical problem, help please?

I just installed my larger alternator, second batter to run all the stereo equipment and my hellroaring isolator (using the starting battery isolation method). I don't think that is relevant to my problem though, but at this point I'm stumped.

So what happens is when I went to lower my engine hatch today, it didn't lower. It clicked at the relay, but no up or down action on the hatch itself. Batteries are charged, but I couldn't get the damn thing to shut. This has happened before, and all I had to do was disconnect the battery cables and then once I hooked them back up everything worked perfect.

But since I just installed the second battery that method of fixing the problem didn't work.

I finally got it to work when I completely disconnected the ground wire running from the aux battery to the engine block, as well as all of the negative cable from the starting Battey.

But what the hell is going on here?? Is it a polarity issue or what? I'm somewhat experienced at this type of thing, but this has my stumped.

I also have the XMD3 radio, and my sirius does a weird thing when I start the boat. Basically, if I leave the boat on the lift overnight and come down the next morning to start it up, before I turn the key I turn the radio on and tune into a sirius radio station. Everything works just fine, music and all; but once I fully start the boat the sirius doesn't work. What happens is that my radio will tell me the station and all the various info, but will not play any of the music, nor allow me to change the station... So we just have to listen to CDs. Again, what the duece??

Is there a bad ground, or am I missing something with polarities in my elecctrical lines??


I really want to get this sorted out, and would appreciate ANYTHING that people can offer to getting this fixed - because I am stumped on what is going on.

So please, help me out!!

When you crank the starter and then release it your system can get a surge back from the starter that is basically a reverse voltage blip. That may glitch the electronics in the radio somehow. Try having the radio completely off, start it, and then turn on the radio. Just a guess, that would not be a common problem or affect.

Your hatch sounds like a corroded connection of some sort on the switched side of the relay. But again it's weird.
Don't ya just love electrics on boats

Thanks Art, I will definately check the connections.

But does this type of stuff sound like a grounding problem to anyone else??

The stereo is now wired to the aux battery and on an accessory switch (so no connection to the starting battery), I'm still waiting to see if this solves the stereo problem. I also am having trouble with me Harmon kardon drive and play, it basically tries to boot up, freezes, reboots, and goes in that cycle. Again, this is on an accessory switch and is in no way connected to the starting battery...