This video shows how to replace Mercedes Benz S400 W221 hybrid DC / DC Converter.

In this guide, you will find instructions on how to replace the HV DC/DC Converter (N83/1) on the Mercedes-Benz hybrid. 

Only trained technicians that have had training on how to work on a high voltage system should perform this repair. Mercedes DC/DC converter is part of the high voltage (HV) hybrid system and can cause injuries or death when it is mishandled. 

What you will need

How to replace the Mercedes-Benz  DC/DC converter. 

  1. Use a professional bi-direction scanner to power down the high voltage system. With your scanner, go to Battery Management Control Module then select Deactivate High Voltage System. This option may be under the Acuations menu. Star Diagnostic Scanner is a good scanner that can be used for this step. This step is highly recommended. Working on the high voltage system without powering down the system can cause injuries and even death. This step can not be completed with scanners such as iCarsoft MB II. deactivate high voltage system mercedes hybrid
  2. Disconnect the 12-volt battery in the trunk. mercedes hybrid 12 volt battery
  3. Loosen the lug nuts for the front right wheel. Jack up the front right of the vehicle and secure it with jack stands. jack up vehicle
  4. Remove the rear splash shield in the front passenger wheel well. Several 10mm nuts need to be removed to be able to take off the splash shield.  Locate the DC/DC converter mounted on the frame of the vehicle. Mercedes dc dc converter
  5. Unplugs the electrical connector that connects to the N83/1 module. MERCEDES DC DC CONVERTER INVERTER REPLACEMENT HYBRIDYou will need to lift up the top part of the connector. As you lift up the top part, the connecter starts to pull out. 
  6. Disconnect the high voltage orange cable that connects to the high voltage battery known as HV Battery (A100). Lift the black/blue ring then pull out the line. MERCEDES DC DC CONVERTER INVERTER REPLACEMENT HYBRID
  7. Disconnect the positive cable at the bottom of the DC/DC converter. MERCEDES DC DC CONVERTER INVERTER REPLACEMENT HYBRID positive terminal
  8. Use channel lock pliers to pull down the clamps for the cooling hoses. MERCEDES DC DC CONVERTER INVERTER REPLACEMENT HYBRID hoses

     

  9. Remove the cooling hoses and plug them so that you don't lose all the coolant. Some coolant will be lost, which you will need to add when you are done replacing the DC/DC converter.  
  10. Remove the bolt that connects to the ground wire. ground wire MERCEDES DC DC CONVERTER INVERTER REPLACEMENT HYBRID
  11. Remove all the 8mm nuts that secure the DC/DC converter to the frame. MERCEDES DC DC CONVERTER INVERTER REPLACEMENT HYBRID removal
  12. Remove the DC/DC converter from the vehicle and replace it. 
  13. Reconnect the 12-volt battery. 
  14. Re-energize the high volt system with a scanner. Clear any fault codes that may be present in the Engine Control Unit, DC/DC control unit, and Battery Management Contol unit. 
  15. Check the engine coolant level and add engine coolant. The level will be slightly low due to the coolant you lost in step 8. 

The pictures in this guide are from a 2010 Mercedes-Benz S400 hybrid, but the procedure is similar for other Mercedes-Benz hybrid models, including the E-Class hybrid. 

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