Replacing battery terminals is not a common automotive repair but it does happen on occasion if the battery is neglected. Corrosion buildup is one of the leading causes to require battery terminals to be replaced. There are a few different styles of terminal clamps that require different procedures to replace them but the overall concept is the same.
Open the hood and then disconnect the black-wired negative battery terminal clamp from the battery first. Use a box-end wrench or a ratchet and socket.
Disconnect the red-wired positive battery terminal clamp next.
Use a pair of wire cutters to snip off the clamp if the wires run inside the lead terminal clamp with no disconnection option. Some top post terminals will feature retaining screw clamps. For this style, simply use the wrenches or ratchet and a suitably sized socket to remove the retaining screws and then remove the clamp from the wire.
Snip the exposed wires back with the wire cutters if necessary to remove any corroded ends on the wires. Strip the plastic wire covering, if there is one, to expose the open wire to the battery terminal. Be sure to leave enough room on the wire to attach to the clamp and properly reach the battery top post.
Reattach the replacement battery terminal. Most replacement terminals do not require internal connection of the battery wires. Simply place the exposed wire inside the retaining clamp and tighten the retaining bolts.
Install the red-wired positive battery terminal first and then the black-wired negative battery terminal next. Be sure to tighten the clamps so they're not loose on the battery post.
Remove the black-wired negative battery terminal from the battery side post first. Use a wrench or a ratchet and socket.
Remove the lead battery bolt from the battery terminal by prying it out with a pair of channel locks. Pull the black covering off the terminal and then cut the wire below the clamp with a pair of wire cutters.
Repeat Step 2 for the red-wired positive side post terminal.
Insert the exposed wire into the replacement terminal and then crimp the end tightly against the wire with the heavy gauge wire crimps. Replace the red plastic terminal covering and then insert the lead battery bolt into the terminal. Use the channel locks to help but be careful not to mar the hex-headed end of the lead bolt. Repeat this step for the black-wired negative terminal.
Install the red positive terminal to the battery first and then tighten the battery lead with a wrench or socket and ratchet. Install the black negative terminal last and tighten the battery lead.
