The 2009 GMC Envoy SLE is equipped with a retained accessory power system that maintains power after the Envoy is turned off. Make note of your radio theft code and station presets, because you will lose them when you disconnect the main battery. If you have On-Star, discharge the RAP system by taking the key out of the ignition, and then opening and closing the driver's door.
Open the hood and ensure that all electrical devices are turned off, and that there are no doors open or lights on anywhere on the vehicle.
Find the battery on the driver side of the engine compartment. Using a ratchet and socket, loosen the terminal bolt on the negative cable and disconnect the cable from the battery terminal. Lay the negative cable aside where it can't touch the battery, then loosen the positive cable bolt and remove the cable.
Disconnect the corrugated battery air duct from the front of the battery box. Look on the rear side of the battery box, and if so equipped, remove the coolant heater cord retainer from the box.
Locate and remove the three battery brace fasteners, then remove the brace from the tray and lift the battery cover up and off the battery. Using a ratchet, extension and socket, remove the battery retainer hardware and lift the battery up and off the tray.
Clean the terminals on the battery cables and clean the posts on the new battery. Lower the fully charged new battery onto the battery tray. Install the battery retainer hardware and torque the nut to 11 foot-pounds using a torque wrench, extension and socket.
Place the cover over the battery and position the battery brace. Install and torque the brace fasteners to 89 inch-pounds, using a torque wrench. Install the battery air duct and, if applicable, the coolant heater cord retainer.
Install the positive cable and bolt on the positive battery terminal, and torque the bolt to 11 foot-pounds. Install the negative cable and bolt, then torque it the same.
Reprogram your radio presets. Start the engine and drive the vehicle so the onboard computer can relearn its adaptive strategies.
