Mercedes-Benz vehicles are known for their advanced technology and luxury, but even the best machines require maintenance. If you’re experiencing warning lights or electrical malfunctions in your GLE 166 or C 400 205, the auxiliary battery may need attention. Here’s a step-by-step guide to diagnosing and replacing the auxiliary battery in these models.
What is the Auxiliary Battery?
The auxiliary battery in Mercedes-Benz models powers the electrical system when the main battery is turned off or when the vehicle is in ECO mode. It plays a crucial role in maintaining comfort and functionality by ensuring that key systems, such as infotainment, power windows, and other electronics, remain operational.
In the GLE 166 and C 400 205, the auxiliary battery is particularly important due to their complex electronic systems. A faulty auxiliary battery may trigger dashboard warning lights or even cause certain systems to stop working altogether.
Symptoms of a Faulty Auxiliary Battery
Here are some common symptoms that indicate your auxiliary battery may need repair or replacement:
- Dashboard Warning Light: You may see a warning light indicating “Auxiliary Battery Malfunction.”
- Electrical Issues: Problems with electronics, such as the infotainment system, windows, or seat adjustments, may indicate that the auxiliary battery is not functioning properly.
- Start/Stop System Malfunction: If the start/stop system fails, it could mean the auxiliary battery is drained or has failed.
If you experience any of these symptoms, follow the steps below to check and replace the auxiliary battery.
Tools Needed
- Socket wrench set
- Plastic trim removal tool
- Multimeter (for testing battery voltage)
- Replacement auxiliary battery
- Safety gloves and glasses
Step-by-Step Guide to Fixing the Auxiliary Battery
Step 1: Locate the Auxiliary Battery
- GLE 166: In the GLE 166, the auxiliary battery is located beneath the passenger-side dashboard.
- C 400 205: In the C 400 205, it’s usually found in the trunk compartment, hidden in the side
- panel.
Step 2: Disconnect the Main Battery
Always disconnect the main battery before working with any electronics to avoid potential shock or short circuits.
- Turn off the engine and remove the key from the ignition.
- Open the hood and locate the main battery.
- Use a socket wrench to loosen the negative (black) battery cable, and disconnect it from the battery terminal.
Step 3: Access the Auxiliary Battery
- GLE 166:
- Use a trim removal tool to carefully remove the trim panel under the passenger-side dashboard.
- Locate the auxiliary battery and carefully detach any clips or mounts holding it in place.
- C 400 205:
- Open the trunk and remove the side panel cover.
- Locate the auxiliary battery compartment and remove the securing brackets.
Step 4: Test the Auxiliary Battery
Before replacing, use a multimeter to test the voltage of the auxiliary battery. A healthy auxiliary battery should read around 12 volts. If the reading is below 11 volts, it’s likely time for a replacement.
Step 5: Replace the Auxiliary Battery
- Once confirmed faulty, carefully remove the old auxiliary battery.
- Place the new auxiliary battery in the compartment.
- Secure it with any clips or brackets, ensuring it’s fastened tightly.
Step 6: Reconnect the Main Battery
- Reconnect the main battery’s negative cable.
- Turn on the ignition and check for any warning lights on the dashboard.
- Test the start/stop functionality and other electrical systems to ensure everything is working properly.
Final Tips
- Reset the Battery Sensor: In some models, you may need to reset the battery sensor using a scan tool. This is often necessary for the vehicle to recognize the new auxiliary battery.
- Dispose of Old Batteries Properly: Dispose of the old battery according to local regulations. Many automotive stores offer recycling services.
Expert Mercedes-Benz Repair Services
Regular maintenance of your Mercedes-Benz’s electrical systems is crucial for performance and longevity. If you encounter any issues beyond the auxiliary battery replacement or prefer professional assistance, feel free to reach out to a certified technician.
As a specialized electrician technician for Mercedes-Benz, I offer reliable and efficient repair services for your luxury vehicle. Whether it’s auxiliary battery replacement or complex electronic diagnostics, you can trust my expertise to get your vehicle back in top shape. Contact me for quality, specialized Mercedes-Benz maintenance and repair services “09015329867” Mercedes Benz engineer Abuja pelubenz.com
