When disconnecting the Car Batteries, it is important to follow certain precautions to prevent damage to the vehicle's systems. The negative terminal should be disconnected first and connected last to avoid shorting the battery. Some systems, like the radio and power door locks, require constant battery power for operation. Before disconnecting the battery, turn off the ignition key and lighting switch to protect semiconductor components. Wait at least 1 minute after turning off the ignition switch before disconnecting the battery on models with a navigation system. Remove the key from the ignition on vehicles with power door locks to prevent accidental engagement when reconnecting the battery. After reconnecting the battery, the Transmission Control Module and engine management system's PCM may need time to relearn their adaptive strategies, resulting in changes in shifting and drivability. The power window system may also need recalibration. Memory savers can be used to maintain security alarm codes and PCM memory while isolating the car battery. To facilitate PCM relearning, start the engine, warm it up, and drive under moderate acceleration and idle conditions until normal performance returns. For power window calibration, turn the ignition switch to "RUN" and use the individual window switches to lower and raise each window while holding the switch in each position for three seconds.