Mercedes Battery Drain Issues
During the life of a vehicle, owners might experience one of the most frustrating issues which is your battery being drained. When your battery is drained, your Mercedes cannot function properly.
Mercedes-Benz is one of the most well-known brands on earth. They create iconic vehicles that are well-crafted and luxurious. You usually love your Mercedes Benz. But, like any car brand, they can experience problems.
If you suddenly find issues with your Mercedes, especially when dealing with electrical issues and battery drain, you should have it looked at by professionals.
Problems like battery draining are possible across all brands and vehicles. Despite being built to high standards, your Mercedes may be less prone to issues like these, but it does not make them completely immune to failure.
Our client came to our workshop needing help with his Mercedes SL350 2003. His car’s battery was completely drained. He told us that it only took four hours to completely drain the battery too, which meant that something was up. Our experts were soon on hand to diagnose and fix the battery drain issue.
Identifying The Problem
Before visiting us, our client went to another Mercedes garage that unsuccessfully tried to repair the battery drain by replacing certain parts. After a diagnostics scan, no fault codes appeared but we dug deeper into finding out what might have caused the issue by tapping into the wiring diagrams and accessing the Mercedes WIS system.
We fully charged the battery and tested it and not to our surprise, it failed the test. We soon replaced the battery so we could perform further tests. Our tests identified a consistent 2.2 Amp drain which rose to 4.5 Amps for around 5 minutes at 15-minute intervals.
Fuses were our next plan of action. Identifying which fuse had current flowing through it even when the vehicle was locked. This usually provides us with one or two fuses which might lead to the circuit that was draining the battery.
We soon discovered that the SAM modules on the front and rear had current flow and a network issue meant the car’s electronics were not communicating information properly.
From here we delved into the CAN network diagrams, finding a way to test both the engine CAN and the interior CAN systems. Our oscilloscope showed that the interior CAN was active, despite the vehicle being locked. Failing to shut down the CAN systems means that the control modules in the network will still operate. So much so that the network believes the car is switched on when it isn’t.
How We Fixed the Problem
Our Mercedes specialist technician replaced the pneumatic control module for the central locking system which made the system not shut down correctly. We discovered as soon as the module was isolated, the CAN system switched off. Two minutes later, the system was dead and communicated no signal. Then, after 35 minutes, the battery drain had reduced to an acceptable 0.050 amps.
After that, we swapped out the control module with a brand-new one. We made sure to program and SCN code it to the vehicle. Then, we ran the tests again. This time, there was no drain, and the CAN system was not active. We went through the interior CAN details and wiring diagram, eliminating each of the 42 control modules until the communication stopped.
But did we finish there? Absolutely not.
Our Customers are our Priority
At South Coast Garage we prioritise our customer’s safety. We knew that our customer had already visited another workshop without success. We possessed the necessary expertise and equipment to diagnose and fix the issue, first time. This ensures that our first-time fixes save customers money and hassle in arranging repairs later down the line.
Instead of fixing the whole system, we fully diagnosed the issue and thanks to our expertise, only replaced what was necessary.
It’s just how we roll!
Mercedes Battery Drain: Conclusion
If you own a Mercedes-Benz and are facing car troubles, follow our clients example and contact our skilled technicians at South Coast Garage.
For your Mercedes-Benz, it’s crucial not to ignore problems. Sometimes issues can slip under the radar, but there are signs to watch out for:
- The check engine light comes on.
- Notice jerking or shaking while driving.
- Listen for strange noises.
- Pay attention to any unusual smells.
- Look for excessive smoke from the exhaust.
- Check for oil leaks.
These are basic indicators. If you notice any, reach out to us! Our certified Mercedes experts are here to help you get back on track.
Give us a call today, and we’ll provide advice or schedule a diagnostics check to pinpoint the problem and save you money.
