A ground strap is a cable that connects an engine block to a framework. There are cases when it will be directly connected to the negative battery terminal, This completes the circuit for electrical devices that are grounded to the engine. When your vehicle doesn’t start and refuses to hold a charge, or your lights flicker or dim, it may be time to replace your battery ground strap. Since these signs can also point to a failing battery, you may need to test your ground. Braid is the conductor of choice where flexibility is required. It is sometimes used for electrically bonding parts of a vehicle, for example an exhaust pipe, door, or hood.