Its in the trunk on the left rear, behind the cover where the wheel well is. After replacement it will have to be reconfigured with the tech 2 and the VCIM(onstar module) will have to be reprogrammed. The battery is a dealer only part. Do not disconnect the main vehicle battery or remove the OnStar fuse with the ignition key in any position other than OFF. Retained accessory power (RAP) should be allowed to time out or be disabled (simply opening the driver's door should disable RAP) before disconnecting power.
Disconnecting power to the OnStar module in any way while the ignition is ON or with RAP activated may cause activation of the OnStar Back-Up Battery (BUB) system and will discharge and permanently damage the back-up battery. This action is per design as the BUB is designed to provide power to the VCIM so an emergency notification call can be made after a vehicle collision where the main battery is disabled.
Once the Back-Up Battery is activated it will stay on until it has completely discharged. The BUB is not rechargeable and once activated the BUB must be replaced.
Friday, July 16th, 2010 AT 5:51 PM