Garmin gps 12 wont turn on.

First, make sure that the unit really does run off of +12V. Most Garmin units really run off of +5VDC and there is a charger/regulator that reduces the +12VDC to +5VDC. Look at the power cable and see what the output voltage is. Does the unit has a USB port?

Power supply damage is most likely and depending on cost of the unit itself may or may not be worth fixing---kind of like hooking a radio up backwards on a 12 volt system--damage is INSTANT and sometimes fatal.

Try charging it, if not plug it onto the Garmin updater manager and update the device software.

if still not working, ask a specialist in the sat nav store they should give you all the details and paperwork to help

unfotunately only an electronics expert can fix this if it is indeed salvageable. You basically have cooked the circuits with the power over load.

Your nuvi 5000 does NOT have a internal battery and that means that you cannot operate it unless it is connected to a 12 volt power source. Connecting it to your computer via USB allows you to install map updates, check for firmware updates, etc, but you will not be able to use it as a gps while it is connected to the computer. There is nothing wrong with your gps.
To use your gps in the home you need to purchase a 12 volt adapter, there are several types, plug the adapter into your wall outlet and connect your gps to it. If you can sit near a window it will help in picking up the satellite signal. Just keep in mind that you cannot connect the 12 volt power supply and use the usb cable at the same time. Enjoy your gps.

You might be able to use the parts from an old cell phone adaptor. Have you tried that?
If not don't mess with any off brand adaptor. Get another one from Garmin at their website Garmin .com

Question: Why won't my unit charge while plugged into my vehicle?
From the Garmin site: --> Answer: If your unit will not charge in your vehicle, you may need to replace the fuse located in the tip of the vehicle power adapter.

1. Unscrew and remove the silver or black, round end piece.
2. Remove the fuse (glass and sliver cylinder) and replace with a new fuse.
3. Ensure that the silver tip is placed in the end piece. Screw on the end piece.

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hpd367 - If your Garmin has died within a year then call them for an RMA number and they will repair/replace it.
Tel 0808 238 0000

Moscow Nell - I had the same problem and got an adaptor from Halfords for about £5.

I had the same problem recently... What I did was open the front casing and hit the reset button under the cover, then it turned on while plugged into the car adapter.