Adding A Circuit

Most new cars come with cigarette lighter sockets that are only hot when the key is on. Not so with my older vehicles, and I'd like to have a 'key off' circuit for my dash cam and GPS. It's not a big deal leaving them on, but if they're off they are less conspicuous when the vehicles are left in a parking lot.

Dash cam and GPS

Trying to find a place to wire in this new 'key off' circuit can be a daunting task. Sure, I can locate a fuse that's for the power windows which will get the job done, but how to get a wire to it? Do I pull out the fuse and jam a bare wire in the socket before jockeying the fuse back in? Actually I have done that on occasion but then there's the headache of fusing the new wire...

Blue wire stuffed under 40 amp fuse

Well there's a much better way and it's painless. Use a fuse tap in place of the selected fuse. This is a wire that has fuse prongs and a place for two fuses. One fuse position is for the original fuse and the other position is for the new circuit.

Fuse Tap - you can see the places for two fuses where the wire comes out of the block

This rig saves a lot of time/trouble and even has a fuse for the new circuit. Nice! But there is one caveat - the fuse tap has to be oriented correctly in the socket. Only one side of the socket is hot so the new lead has to be tied to that side...if your new circuit doesn't work, pull the fuse tap out and put it in the other way. Now we're cookin'

Fuse tap in place with both fuses installed.

The new wire is only rated for 10 amps so you're not going to be able to run an actual cigarette lighter, but it is fine for almost anything else.

My daughter wants one of there for her car, but for the opposite reason. She needs a circuit that's always hot so she can charge her cell phone when the key is off.