How to add a circuit to a car fuse block

Updated April 17, 2017

Adding a circuit connection into your car's stock fuel box is the simplest way to wire custom electronic accessories. The complication of deciphering and splicing into the stock vehicle wiring harness can be avoided when using a fuse tap. Fuse taps are fuse designs which incorporate a wiring connection and crimp. This allows you to draw power from a stock fuse location by simply plugging your electronic accessory's power wire into the fuse tap connection.

Disconnect the vehicle battery cables. This is to ensure user safety when working with any part of the vehicle's electrical system, such as the fuse panel.

Locate the vehicle fuse box you wish to tap into. For exterior and engine bay accessories, such as headlights or underglow kits, use the fuse box located in the engine compartment next to the vehicle battery. For interior accessories, such as stereos and gauges, use the interior vehicle fuse box, generally located in the driver's side footwell area.

Unclip and remove the plastic fuse box cover. Printed on the cover you will find a diagram of the stock fuse layout. Use this diagram to choose which fuse location to tap. For example, if you're wiring an accessory that requires a constant power source, use one of the stock 12-volt power fuse locations. For lighting accessories such as headlights and illuminating gauges, use the stock headlight or dashboard lighting fuses. This will make your accessories turn on and off with the stock headlight switch.

Grip the sides of the desired fuse with a fuse puller tool and gently pry it out of its slot. Plug a fuse tap in place of the stock fuse. Route your accessory's power wire to the fuse tap location. Strip approximately 10mm of insulation from the wire's end and insert it into the fuse tap connection. Pinch the connection tight with pliers. Secure and insulate the connection with electrical tape, if necessary.

Replace the fuse box cover. Reconnect the vehicle battery cables.

Things You'll Need

  • Fuse tap
  • Fuse puller
  • Wire strippers
  • Electrical tape
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About the Author

Alexander Eliot has been a professional writer since 2006. He holds a B.A. in English literature from the University of Cincinnati. His academic background allows him to write articles in all fields of education, as well as science and philosophy. Eliot once worked for a performance auto center, an experience he draws from to write informative articles in automotive theory, maintenance and customization.