Replacing a car battery on older vehicles used to be simple. You unhooked the battery and installed the new one. Late-model vehicles, however, rely on computers that operate everything from the stereo to the transmission. If power is lost to the computers, the settings are lost and reset to default. This means the vehicle may feel different when...
M/F Purchase a small 9-volt memory saver. These inexpensive devices are sold at most automotive supply stores. The memory saver is plugged into a 12-volt accessory outlet or cigarette lighter on your vehicle. It contains a 9-volt battery that provides a constant charge to the vehicle's system while the main battery is removed.
M/F Ensure the memory saver's 9-volt battery is fresh and then plug the memory saver into the accessory outlet or cigarette lighter. Also make certain the memory saver is working after it's plugged in. An indicator light should let you know if power is reaching the device. You may have to turn the vehicle's ignition switch to the accessory or "ACC" position for the memory saver to work.
M/F Turn off all the other accessories on the vehicle, ensuring that all lights are off, including the dome light and trunk light. If the vehicle has a light under the hood, unscrew the bulb. Anything that requires electricity will quickly drain the 9-volt battery in the memory saver.
M/F Remove the car battery from the vehicle. Each make and model will vary, but most will require you to remove a plastic cover, guards and perhaps a mounting bracket. Use the necessary wrenches to remove these parts, then disconnect the negative (or black) and positive (or red) cables from the battery terminals. Remove the negative ( - ) cable first, followed by the positive ( + ) cable.
M/F Install the new battery as quickly as possible. Reconnect the positive cable before attaching the negative cable. Ensure both cables are securely fastened to the battery terminals and replace any guards, brackets or covers you removed.
M/F Turn the ignition on the vehicle and start the engine. Unplug the memory saver from the outlet or cigarette lighter.