Mercedes-Benz Hybrid High Voltage B

Mercedes-Benz Hybrid High Voltage Battery – Resistance Check

One of the components that can fail and lead to no-start conditions on a Mercedes-Benz hybrid vehicle is the high voltage (HV) battery.

This short guide shows how to check the resistance of the high-voltage battery. This post is for information purposes only, and trained technicians should only perform these steps. When performing this procedure, make sure to wear appropriate gloves.

interlock insulation resistance contactor

The first step is to use a good scanner, such as a YOUCANIC scanner, to read the Battery Management System (BMS) codes. Also, go to live data to check the actual value of the resistance – item 087- isolation resistance.

  1. Disable the high voltage system using a professional bi-directional scanner.
  2. Disconnect the 12-volt battery in the trunk.mercedes small 12 volt battery
  3. Open the hood and locate the hybrid high-voltage battery on the passenger side. On some Mercedes-Benz models, the hybrid battery may be in the trunk.
  4. Unplug the electrical connector from the high-voltage battery.
  5. Loosen the 10mm bolt and disconnect the orange cable connecting the A/C and power electronic module. mercedes hybrid battery cable
  6. Pull the black ring up on the orange cable from the DC/DC converter, then pull out the cable. mercedes hybrid battery cable removed read to test
  7. Set a digital multimeter to measure the current. The reading should be under 2 ohms. test mercedes hybrid battery
  8. Measure the resistance between the two terminals shown in the picture. mercedes how to test hybrid battery s400

If the resistance is below two ohms, the battery is ok. If the resistance is above two ohms, the battery is not good and needs to be replaced.

Keep in mind that even if the battery shows under two ohms, it may still not charge and be faulty due to internal failure. This test was performed on a 2010 Mercedes-Benz S400 hybrid.

 Get Help

If you are having issues with the hybrid, please “contact the YOUCANIC” team with any questions that you may have. We can help you troubleshoot the problem FREE of charge as long as you send us the codes. We need the codes from these four modules:

  • Engine ECU,
  • DC/DC converter,
  • BMS,
  • Power Electronics Module

Once we have the codes, we can tell you if you have a bad power electronic module, hybrid battery, or both.

If your vehicle is at the dealership or mechanic, ask them for the list of codes and send them to us.    If you want to ship the car to Baltimore, we can repair it at a fraction of the dealer’s cost. We love these cars and believe it is a sin to pay over $10k to keep them running.

mercedes hybrid problems

We hope you find the Mercedes-Benz Hybrid High Voltage Battery =Resistance Check guide helpful. Check these troubleshooting and repair guides for more help on your Mercedes-Benz.


  • Rushit Hila • ASE Certified

    Rushit Hila, an ASE-certified engineer (G1 Automotive Maintenance and Repair), brings over two decades of hands-on experience in the automotive world to his writing. With a strong educational background, including a Master of Science in Engineering and a Bachelor of Science in Engineering, he has honed his skills and expertise through years of practical work. As a respected authority in the field, Mr. Hila is dedicated to offering insightful and valuable content that resonates with both vehicle owners and mechanics.

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