Replacing a malfunctioning auxiliary battery in a Mercedes-Benz C300 might seem daunting, but it’s a surprisingly manageable DIY task. This guide provides a step-by-step walkthrough for replacing the auxiliary battery in a 2015 W205 C300, based on a personal experience. While a Mercedes-Benz technician might indicate this malfunction isn’t critical, addressing it promptly can prevent potential future issues.
Locating and Accessing the Auxiliary Battery
The auxiliary battery in the W205 C300 is located beneath the glove compartment. To access it, you’ll need to remove a few components:
- Glove Compartment Undercover: Start by removing the undercover beneath the glove compartment. This typically involves removing a single screw and carefully detaching two clips.
- Cable Detachment: Two cables connected to bulbs are attached to this undercover. Disconnect both cables to prevent any accidental damage.
- Carpet Removal: Carefully pull back the carpet. It might require some effort, but the foam backing can be twisted without causing damage.
- Plastic Cover Removal: Once the carpet is pulled back, you’ll see a plastic cover secured by three nuts. Remove these nuts and the plastic cover to reveal the voltage converter and the auxiliary battery.
Replacing the Auxiliary Battery
With the auxiliary battery exposed, follow these steps for replacement:
- Voltage Converter Removal: The voltage converter is attached to a metal piece by a clip and a screw. Carefully remove the nut securing the screw and unplug the converter. The auxiliary battery is located directly behind it.
- Auxiliary Battery Detachment: Disconnect the negative terminal first, followed by the positive terminal. Carefully remove the old battery.
- New Battery Installation: Install the new auxiliary battery, connecting the positive terminal first, then the negative terminal. Secure the battery in its designated location.
- Reassembly: Reinstall the voltage converter, plastic cover, carpet, cables, and glove compartment undercover in reverse order of removal.
Important Considerations
Exercise caution while working in this area, as there are numerous DC cables under the carpet. Avoid using excessive force or making sudden movements that could damage these cables. Using the correct tools and working slowly and methodically is crucial. The entire process should take approximately 35 minutes.
This guide provides a general overview. Always consult your vehicle’s owner’s manual for specific instructions and safety precautions. If you’re uncomfortable performing this task yourself, consult a qualified mechanic. While this specific experience references purchasing a replacement battery online, sourcing the part from a certified dealer can ensure compatibility and warranty coverage. Remember, a functioning auxiliary battery is essential for various vehicle systems.
