Backup Battery And Low-Voltage Disconnect: General Motors

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When an accident happens, how will you call for help? Maybe the telematics system, equipped with a backup battery, could automatically do this, even if the main power is cut off. What are the repair considerations, and where can information be found for backup batteries? Let’s see what General Motors (GM) has to say.

GM has vehicle-specific service information for OnStar-equipped backup batteries that is found in different areas. This information may include precautions around the disconnection of the low-voltage battery and the replacement of the backup battery. If the backup battery is equipped, it may be embedded into the Telematics Control Module (TCM) or Telematics Communications Interface Control Module (TCICM). This may require the complete module replacement unless a specific backup battery replacement procedure exists.

The Battery Disconnect Warning document is found in vehicle-specific service information under: Preface ➤ Danger, Warnings, And Cautions ➤ Battery Disconnect Warning. It is typically linked or noted in the low-voltage battery disconnect procedure.

Per the Battery Disconnect Warning document:

  • "Do not disconnect the main vehicle battery or remove the OnStar fuse with the ignition key in any position other than OFF."
  • "Disconnecting power to the OnStar module in any way while the ignition is On or with retained accessory power activated may cause activation of the OnStar® Back-Up Battery system and will discharge and permanently damage the back-up battery."
  • "The back-up battery is not rechargeable and once activated the back-up battery must be replaced."

Vehicle-specific information for the backup battery is located under: Driver Information And Entertainment ➤ Cellular, Entertainment, And Navigation ➤ Description And Operation.

The OnStar Description And Operation document includes:

  • Backup battery replacement requirement
  • Battery nominal voltage and chemistry

If available, the backup battery replacement procedure can be found under: Driver Information And Entertainment ➤ Cellular, Entertainment, And Navigation ➤ Repair Instructions. This area also includes other replacement procedures, such as the module that may contain the backup batteries.

Some vehicles may require the Backup Battery Reset procedure to be performed after a replacement. This procedure is found under: Driver Information And Entertainment ➤ Cellular, Entertainment, And Navigation ➤ Diagnostic Information and Procedures.

Always follow OEM vehicle-specific service information when disconnecting the low-voltage battery and ensure all post-repair calibrations and initializations are completed.

For additional GM information, check out the following pages:
Chevrolet OEM Information
GMC OEM Information
Buick OEM Information
Cadillac OEM Information

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