DC Outlets Frying All Adapters

2013 Supra Sunsport 22v - I've been trying to plug a usb adapter into the DC sockets throughout the boat. First one I plugged in a was a cheap nothing adapter you can get at any convenience store or WalMart and it instantly stopped working. Thought it was kind of weird, but being cheap decided I'd try another one in a different socket, same result. I reset the breakers under the driver side and checked the grounding wires thinking it might be a grounding issue. Even used a voltmeter on each socket and was each one was reading exactly 12V, so I figured it was safe to try a nicer newer adapter and it fried it too. The adapters only pull 1.5amps each. Lastly, I tried an old iTrip I had and same result, it won't turn on, and if I plug it in a truck it won't come on now. I checked my trucks setup and it seems to be the same, 12V at the socket with a 15amp fuse.

I'm at a loss here. Everything I can think of seems to be working as it should be. I know the breakers are 15 amp, but I wouldn't think that means each one of these sockets are constantly pumping out 15 amps. Anyone seen or heard anything like this before? I would really love the help.

Are your devices tripping breakers when plugged in?

You should have multiple circuits for the port and starb receptacle @ 15a.


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No they just go dead. The circuits haven't tripped at all. I worked on it more last night and found that someone had wired the outlet in the glovebox backwards, (-) to the post, and (+) to the casing. So that explains the port side and all the adapters going bad from when I plugged them in there. I checked the wiring of the outlet near the drivers seat and it was done correctly, then I checked the one behind the seat and it has a positive 12V with positive to the post and negative to the casing. When I tested the one in the glovebox before, I didn't realize when it was wired wrong my voltmeter was reading -12Vs. That should have given it away, but the starboard side are both reading positive 12vs, so i'm assuming they are wired correctly. I'm getting a couple more cheap adapters today to see if they will work now that i've got the glovebox one wired correctly.

Most of those ACC to USB adapters have a fuse inside. Open them up and see if the fuse has blown. May take an ohm meter to test the fuse as the are a small value and small. You said you checked voltage on the sockets. Was the polarity correct? Center contact is the B+ and the metal band around the inside wall is the B-. If the adaptor died after a USB/phone was plugged in, then this points to the cable/phone.

Thanks everyone. Not sure why it caused the right side to fail, but once i fixed the wiring on the outlet in the glovebox the others started working properly, so all outlets are up an running. Thank you for you insight in helping me fix the issue!!!