How to wire a car lighter adapter plug

Written by steve hamilton
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How to wire a car lighter adapter plug
These handy adaptors can power all sorts of gadgets. (adaptor image by andreas from

As cup-holders replace ashtrays in new cars, cigarette lighters become superfluous. Smokers no doubt disagree, as does anyone who uses the cigarette lighter plug to power various 12VDC devices. Automakers realise this, and many if not most install vehicle power accessory outlets. It is rare to find a car or truck without at least one of these handy outlets, and many have one for each passenger seat. They are useful for plugging in cell phone chargers, mp3 players and other electronic devices.

Skill level:

Things you need

  • 12VDC vehicle power accessory outlet kit
  • Power drill
  • Drill bits
  • Screwdrivers
  • Combination wire cutter/stripper/crimping tool
  • 12VDC power adaptor plug

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  1. 1

    Decide on a location for the outlet and mount it using the hardware supplied with the kit. Be careful drilling holes. There is often little room for error behind dashboards or trim panels.

  2. 2

    Select an accessory terminal in the vehicle fuse box to power the outlet. Use piggyback connectors to expand the number of available terminals if necessary. Make sure any other positive terminal or wire you connect to is only live when the vehicle is on. Otherwise, devices you leave plugged into the outlet could discharge your vehicle battery.

  3. 3

    Use the wiring supplied with the outlet if possible. Otherwise, make sure the gauge of wire you select is appropriate for the rated amperage of the outlet. Cut the wires to length. As a rule of thumb, the negative wire is black or green and will only need to run as far as the nearest ground; the positive wire is red and needs to reach from the outlet to the fuse box.

  4. 4

    Connect the positive wire to the fuse box and outlet centre terminal. Connect the negative wire from ground to either the body of the 12VDC power outlet or its internal metal sleeve. Some outlets use crimp-on terminals, while others use screws or special no-strip connectors. Consult the kit manufacturer's instructions.

  5. 5

    Examine the device you want to connect. Look for markings indicating the polarity of its input jack. Consult the device manufacturer's documentation if in doubt. Wire the centre connector on the power adaptor plug---usually a spring-loaded button---to the device positive input connector or jack. The remaining connection is the ground.

Tips and warnings

  • Consult your vehicle manual before wiring any accessories.
  • Pull the fuse out of the circuit you're working on until you get everything connected properly.
  • Plug-in adaptors are available that can convert 12VDC to other voltages and have a selection of the most common device input plugs already attached.

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