How to Run a Wire From a Battery to the Inside of the Car in a Ford Focus

Written by paul vaughn
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How to Run a Wire From a Battery to the Inside of the Car in a Ford Focus
Car wiring must be done carefully and properly. (power wiring image by Aleksandr Ugorenkov from

Vehicle owners often add accessories that require new wiring from the battery to new components in their Ford Focus cars. The wires must be laid carefully and properly so the original equipment is protected and so any new accessory works properly.

Skill level:

Things you need

  • 22-gauge black and red wire
  • 3/8-inch ring connector
  • 22-gauge wire connector
  • Wire-stripping pliers
  • Plastic wire cover
  • Zip ties
  • Crescent wrench

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  1. 1

    Use the crescent wrench to loosen and disconnect the battery cables. The Ford Focus has side-mount batteries on most models.

  2. 2

    Use the pliers to strip about half an inch of insulation from each end of the red wire. Preparing wires for hookup generally is the same for all vehicles.

  3. 3

    Use the pliers' 22-gauge crimp notch to attach the 3/8-inch ring connector to one end of the red 22-gauge wire.

  4. 4

    Cover the length of the wire with the plastic wire cover to protect it from vibration and debris damage.

  5. 5

    Use the zip ties to secure the length of the wire from the battery to the engine compartment's firewall, where it will be put through the firewall's wire harness. Good locations for the Ford Focus are along the right bumper and across the firewire to the main wire harness.

  6. 6

    Run the new wire through the vehicle's original wire harness to the new component to be installed.

  7. 7

    Use the appropriate type of 22-gauge wire connect to link the black wire to the new component and a ground point and the red wire to the live connection. All vehicles use a "hot" wire and a ground wire to properly power a new component.

  8. 8

    Connect the red wire to the red terminal on the battery, and use the crescent wrench to reconnect the battery cables. Depending on the type of component to be wired, the process could take from 20 minutes to an hour from battery to component.

Tips and warnings

  • Examine the new wire you are installing to make sure it is in good shape, end to end, to avoid problems later.
  • Connection types vary, depending on the type of battery post and component connection. Purchase your connectors accordingly.
  • Hand the battery cables carefully. The battery can shock you and cause severe injury.
  • Battery voltage that is connected improperly can damage the new component.

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