MERCEDES-BENZ · 2025-09-15
Complaint Instrument cluster warning lamp and/or warning message for brake system, EPB, ESP (yellow or red) and possibly 12V battery (red) Different combinations of the following DTCs present in the ESP: B23AA77, B23AB77, B23D177 and in part (C100BE0, C100BE1, B23AA1B, B23D152) Cause Due to a reduction in resistance at the HV voltage divider, the DC/DC converter measures an incorrect HV voltage. Regulation of the 12 V output voltage therefore becomes unstable. I.e. the output voltage starts to fluctuate and the output current starts to jump instead of slowly regulating to the currently requested value. The EPB position is calculated by the voltage and the current. Since these fluctuate, the ESP control unit loses its position and sets the DTCs. Remedy Check of the DC/DC converter via…