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AV-SCANNER / Service function guides / Driver assistance and hybrid
This guide covers the complete service procedure for the small 12-volt auxiliary battery used in hybrid vehicles, from understanding its role in the high-voltage system to testing, removal, replacement, and verification. It is written for working mechanics and experienced DIYers who already understand basic electrical testing and are comfortable working around high-voltage components with proper precautions. After reading, you will be able to diagnose a failing auxiliary battery, perform a safe replacement, and confirm that the hybrid system returns to normal operation without setting new faults.
Guidance is general and covers many makes. Exact procedures and values vary by model, so confirm them in the factory service information for your vehicle.
Download all 12 sections as a branded PDF to use in the workshop.
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