Changing your Mercedes-Benz ML350 battery might seem daunting, but with the right guidance, it’s a task you can confidently tackle at home. This guide, created by a Mercedes-Benz repair expert, supplements the official instructions and highlights crucial steps often overlooked, ensuring a smooth and successful Mercedes Battery Change. Save yourself time and money by following these expert tips and avoid costly dealership services.
Preparing for Your Mercedes Battery Change
Before you begin your mercedes battery change, ensure you have everything you need for a safe and efficient process. Crucially, remember that your Mercedes needs power to adjust the seat for battery access. This means you’ll need a jump starter, jump cables connected to another vehicle, or enough residual battery power to move the seat.
Here’s what you’ll need:
- New Battery (Duralast H8-AG or equivalent AGM battery recommended)
- 13mm socket wrench
- Long extension for socket wrench
- Piece of paper (for socket nut trick)
- Jump starter or jump cables (if needed)
- Basic hand tools as per official instructions (refer to the PDF linked below for complete tool list)
Note: Always prioritize safety when working with car batteries. Refer to the official Mercedes-Benz instructions for complete safety guidelines and precautions.
Link to Official Mercedes-Benz Battery Change Instructions
Step-by-Step Mercedes Battery Change Guide for ML350
This guide provides supplementary steps to the official Mercedes-Benz battery replacement instructions. It is essential to read the official PDF document in conjunction with these steps for a complete understanding of the process.
Step 1: Accessing the Battery
The Mercedes ML350 battery is located under the passenger seat. To access it, you must move the seat forward.
- Ensure your vehicle has power. Use a jump starter or another car if necessary to provide power.
- Use the electronic seat controls to move the passenger seat all the way forward and upwards. You may need to move it back and forth slightly to get optimal access.
Alt text: Location of the car battery under the passenger seat of a Mercedes ML350, highlighting the access point.
Step 2: Disconnecting Battery Terminals
Safety first! Always disconnect the negative terminal before the positive to prevent accidental shorts.
- Locate the positive (+) and negative (-) battery terminals.
- Using your wrench, loosen the nut on the forward positive terminal. Leave it connected for now.
- Slide the seat all the way forward and up again to maximize workspace.
- Go to the rear negative terminal and disconnect the rear ground (negative) terminal.
- After disconnecting the negative terminal, reach under the carpet from the back and carefully pull the positive battery connection up and to the right, moving it out of your working area.
Step 3: Removing the Old Battery
Now you can safely remove the old battery.
- Important: You do not need to cut the carpet as suggested in some instructions. There is enough flexibility to maneuver the battery. While cutting might make it slightly easier, it’s unnecessary.
- Tuck the battery vent tube and the negative terminal behind the metal flanges of the battery box. This protects them from damage during battery removal and installation.
- Use your 13mm socket and long extension to remove the rear battery hold-down bracket. This is the only bracket securing the battery.
- Carefully slide the old battery out of the battery box.
Alt text: Mechanic carefully removing the old car battery from the battery compartment of a Mercedes ML350 during a battery change.
Step 4: Installing the New Battery
Installation is essentially the reverse of removal.
- Carefully slide the new battery into the battery box, ensuring it’s correctly positioned.
Step 5: Reconnecting Battery Terminals
Reconnect the terminals in reverse order – positive last.
- Reconnect the positive (+) terminal.
- Reconnect the negative (-) terminal.
Step 6: Securing the Battery
Ensure the battery is firmly secured in place.
- Reinstall the battery hold-down bracket using your 13mm socket and long extension.
- Pro Tip: To hold the nut in the socket while reaching the threads between the battery and the back wall of the battery box, insert a small piece of paper into the socket. This creates enough friction to hold the nut in place, making reconnection much easier.
Step 7: Reinstalling Battery Box Cover and Vent
- Reinstall the battery box cover.
- Remember the rear AC vent is attached to the cover with a plastic push pin. Remove the push pin, detach the vent, install the cover alone, then slide the vent back on top of the cover, connecting it to the vent on the left.
- Slide the seat all the way back. From the front, reach under the seat and carpet to reinstall the push pin from the top, securing the AC vent to the battery box cover. Insert the outer pin first, then push the inner pin into place.
Step 8: Crucial ECU Reset After Mercedes Battery Change
IMPORTANT: This step is critical! After completing your mercedes battery change, you MUST reset the ECU (Engine Control Unit). If you skip this step, your ML350 might start, but you will likely be unable to shift out of park. This vital information is surprisingly absent from the owner’s manual.
Here’s how to reset the ECU:
- For Keyless Go vehicles: Pop off the Keyless Go button to expose the key slot.
- Insert your Mercedes-Benz key.
- Turn the key to the “ON” position (just before starting the engine). Leave it in the “ON” position for at least 2 minutes.
- Turn the key to the “OFF” position, but leave the key in the ignition for at least 10 seconds.
- After at least 10 seconds, turn the key back to the “ON” position.
- Press and hold the brake pedal.
- Turn the key to “START” to start the engine.
- Verify that you can now shift gears out of park.
- For Keyless Go vehicles: Reinstall the Keyless Go button.
Alt text: Steps to perform an ECU reset in a Mercedes-Benz vehicle after a battery change, highlighting the key positions and timing.
Choosing the Right Battery for Your Mercedes ML350
For a reliable mercedes battery change, selecting the correct battery is essential. The Duralast H8-AG AGM battery (available at AutoZone) is an excellent and cost-effective choice. This AGM battery is identical to the Mercedes OEM battery, often produced in the same Johnson Controls factory.
Avoid overpaying at dealerships. Mercedes dealerships often charge significantly more for the same battery, sometimes including hefty labor fees for a simple mercedes battery change. By performing this DIY task, you can save hundreds of dollars.
Link to Duralast H8-AG Battery at AutoZone
Conclusion
Performing a mercedes battery change at home is a manageable task with the correct instructions and a bit of patience. By following this guide and remembering the crucial ECU reset step, you can confidently replace your Mercedes ML350 battery, save money, and gain a sense of accomplishment. Remember to always consult your vehicle’s manual and the official instructions for complete safety guidelines. Happy DIY-ing!
