DC/DC not charging 12v battery (Gateway Comm Issues?)

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New member
Apr 18, 2024
Portland Oregon
Howdy folks,
I've got quite a bit of experience working on the B-Class (rebuilt lots of drive units, replaced OBVCs, etc.), however I've come across one that has a bit of a puzzling issue that I've never encountered. When the car is started, the DC/DC converter does not power on to charge the 12v battery. Other than this, the car functions normally, charges just fine, drives fine, etc, until of course the 12v starts to get too low, then the car starts freaking out...

While it *could* be a DC/DC problem, my thought is that there is a communication issue with the Powertrain Gateway, as I've been unable to connect to it with my scan equipment, and the car also throws several intermittent loss of CAN messages related to the Gateway.

Curious to see if anyone has encountered this issue before and fixed it, before I start throwing parts at it...