Designed for bench testing, diagnosis, and functional verification of the 48V mild hybrid belt starter generator (part number 4N0 903 028) fitted on AUDI A6/S6, A7, A8, Q7, and Q8 models. This tool enables starter motor activation and generator performance evaluation under bench conditions.
Important Notes:
A dedicated 48V battery is required to power the starter motor during testing.
The test tool itself must be connected to a 12V DC power source for operation.
Prolonged bench operation of the water-cooled starter generator is not recommended, as the bench setup cannot provide the necessary cooling to prevent overheating.
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For more information: 
https://www.shiningnev.com/product-page/audi-a6-a7-a8-s8-d5-2017-2023-48v-alternator-control-board-oe-no-4n1903028