Converter assembly power supply

Hi, I'm one of the auto experts on RepairPal's Car Genius team! Great question. I assume you are referring to the DC/DC converter on your 2021 Sierra 1500. This is generally located behind the driver side rear seat back. The seat back will need to be removed to gain access. That being said, working on power supply components on a modern truck like yours involves some complex electrical systems, and I’d recommend consulting a factory service manual for your specific VIN before attempting any work on that component. If you're not entirely comfortable working with electrical systems a qualified shop can locate and address the issue safely and correctly. If you need any further advice or would like help finding a trusted RepairPal shop in your area or even getting an appointment booked, please feel free to call us at 877-913-1554 or check out https://repairpal.com/certified