The negative battery cable bolts to the negative battery terminal on an automotive battery. The other end of the cable bolts to a bare metal ground within the engine bay. It usually bolts to the engine block. This creates a ground between the battery and your vehicle. If the cable snaps inside the thick rubber insulation, it breaks the ground in the vehicle. Without the ground, your vehicle will not start.
Loosen the bolt that secures the negative cable connector to the negative terminal with a socket and ratchet.
Pull the negative cable connector off the negative terminal.
Trace the negative wire to the location where it bolts to the engine block and remove the bolt that secures the wire to the block with a socket and ratchet.
Pull the wire out of the engine bay. In some cases, a second, smaller wire extends from the negative cable. This is a fail-safe wire in case the wire comes loose from the engine block. If your ground wire has a fail-safe wire, remove the bolt that secures it to the engine block with a socket and ratchet.
Place the new wire against the engine block and secure it using the bolt, socket and ratchet. If the wire has a fail-safe wire, secure it to the engine block as well.
Place the terminal connector for the replacement negative cable onto the negative battery terminal and tighten the clamp bolt with the socket and ratchet.
