TechnicianVision · Knowledge base
Backup Batteries and Main Battery Disconnect
I-CAR · April 9, 2019 · General Motors, Toyota, FCA, Chevrolet
Summary
This document explains the function of backup, auxiliary, or supplemental batteries which maintain power to emergency systems like GM OnStar, Toyota Safety Connect, and FCA Assist when the main 12V battery is disconnected. It highlights that improper main battery disconnection while the ignition is on can permanently drain these non-rechargeable backup batteries, requiring their replacement.
What to do on the job
Always ensure the vehicle ignition is completely OFF and retained accessory power is deactivated before disconnecting the main 12V battery or removing fuses to prevent accidental activation and depletion of non-rechargeable backup batteries.
How to use it
Use this document to justify labor time for researching OEM-specific battery disconnection procedures and to support the cost of replacing backup batteries (such as the OnStar telematics battery) if they were depleted due to improper disconnection prior to the vehicle arriving at the shop or during emergency towing operations.
This page is a summary written by TechnicianVision. The document itself belongs to its publisher — follow the link above to read it in full.
TechnicianVision puts procedures like this next to the repair order you are working on. Create a free account →