How do you find out why the 12 Volt power outlet in a car is not working?

Answer 1

1. One reason for such a socket outlet not working is that the fuse for its supply circuit has blown because something was plugged in that took too much current.

2. Or perhaps someone put too small a fuse into the fuse socket after the original fuse blew for some reason, and that fuse has now blown because the thing you were trying to use it for took too much current?

3. If it is a very old car, the fuse wire may have been made of a kind of metal alloy that "ages" so that it can crumble away. (A 1977 245 Volvo Estate I once owned had fuses that did that!)

In any of those cases you should find and check the fuse for the circuit that the 12 volt outlet is wired into, to see if it has blown.

If you have the owner's manual for the car - or a workshop manual - it would save you some time if you looked up the fuse for the socket outlet in the manual first. You would be able to see the correct size of fuse (the amperage), exactly which fuse box to open up and the exact location of the fuse in the box.

If the fuse is ok then you will have to use a voltmeter to trace the supply from the car's battery to find out if a wire somewhere in the circuit is broken.

Another possible reason is that the 12 Volt socket outlet itself has been damaged. That can happen if someone uses too much force trying to get the plug of a mobile phone charger or similar to work. Some plugs on such devices are very slightly larger than the cigar lighter which comes with the socket so, as the connections inside this kind of socket outlet are very fragile, it's best never to force plugs into them.