Mechanics

Battery Cable Replacement

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Step by step instructions on how to replace battery cables. This article pertains to most vehicles.

Difficulty Scale: 3 of 10 Tools and Supplies Needed

  • Wrench set
  • Wire brush
  • Shop towels
  • Baking soda
  • Cable replacement
Before we begin park the vehicle on a level surface, engage the parking brake, engine off.

Step 1 - Once you locate the battery, use a box end wrench to loosen the negative battery cable first. Once the bolts are loose, twist the terminal back and forth while you pull it off. (Note: This is for a top post battery. If your vehicle has the terminals located on the side of the battery, once the bolt is loose, it will simply come off the battery).

Step 2 - Next, use the box end wrench and loosen the positive battery cable. Follow the same procedure from step 1 to remove it.

Step 3 - Follow the negative cable to where it mounts on the engine block. Unbolt it from that location and remove the entire cable.

Step 4 - Bolt the new cable to the engine block.

Step 5 - Next, follow the positive cable to the starter solenoid and unbolt it, then reinstall the new cable. (Note: When routing new cables, make sure they are both clear of fans, the exhaust system, or any other moving parts. If the positive cable melts through from heat or is damaged from a steel moving part, it will short out and can possibly cause a fire.

Step 6 - After the new cables have been bolted in place and properly routed, check the battery terminals. If there is corrosion on them, take a wire brush and gently clean all the corrosion off. Also, use a shop towel to dust all corrosion from the battery.

Step 7 - Once the battery terminals are clean and the new cables have been installed, reconnect the positive cable to the battery first and tighten it. (Note: Battery cables need to be snug, not super tight.)

Step 8 - Next, reinstall the negative terminal onto the battery to complete the job.


Helpful Information

Battery cable connections are the first place to check when major electrical issues begin. In addition to a good battery, the terminals that connect the battery to the vehicle can go bad, corrode, and fail. Therefore, its important to check cable condition at regular service intervals. Check for cracking on the insulation and corrosion on the terminals. Battery acid can cause corrosion inside the battery cables and will inhibiting electrical flow. To check for this condition look for bulges near the top of the cable, these bulges indicate corrosion expansion caused by the chemical reaction between the acid and copper wire.

Best Practices

  • Always disconnect the negative battery cable first and last to avoid a short circuit.
  • When working with a battery, acid is present so wear protective gloves, eyewear and clothing.
  • Never touch a car battery with bare hands. The battery could have residual acid on the surface which is difficult to detect. This acid can ruin clothing and be harmful to eyes and skin.
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AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-11-24)