It is recommended that when handling any electrical component of the vehicle, the negative (-) battery cable should be disconnected to avoid the possible damage to delicate and sensitive electrical parts such as the Engine Control Module (ECM), radio, and alternator. The negative cable should always be disconnected first to prevent the possibility of grounding the positive connector to the vehicle body and causing any damage to these parts. Always make sure the ignition is in the OFF position before unplugging the cables or they will draw current and produce arcing which may damage internal parts including the alternator diodes. Once the battery cables are reconnected (last to be connected is negative cable), ensure that the lights, windshield wipers, and other systems that use electric power to operate, are working correctly. In case the vehicle is having an Electronically Tuned Radio (ETR), it is important to reset radio stations and the clock too.