To disconnect the battery cable(s), perform the following:
- Make sure the ignition switch is OFF .
Disconnecting the negative battery cable FIRST with the ignition turned OFF is required to prevent unwanted surges through the electrical system. If a voltage spike is fed through the system, delicate and expensive componentry (like the engine control unit) could be destroyed in fractions of a second.
- Use the appropriate size wrench(es) to loosen the hardware on the cable clamps. ALWAYS begin with the negative battery cable.
- If necessary, use a puller tool designed for battery cable clamps and remove the clamp, then isolate it from the battery terminal.
- Remove the positive battery cable, if required, once the negative battery cable has been removed.