"Auxiliary Battery Malfunction" just reappeared on my 2015 E350 at roughly 49K miles. Dealer addressed this issue under warranty the previous time. I noticed the brake "Hold" function is not working along with said error. My car has "KEYLESS-Go" and the annoying “ECO start/stop” function that I switch-off every time I start my vehicle. That said, does anyone know if my car has two or three batteries (engine, trunk, dash)? The main engine and smaller trunk batteries are clearly visible, but I have not investigated finding a dash battery. Any insight would be appreciated. Thanks