You may have been wondering why the “Battery protection: Convenience functions temporary unavailable” warning came up. Your car still runs and drives normal.
- Leave the car sitting for several days, without starting it.
- Let your radio or lights on with the engine off.
- Have a battery that is reaching the end of its useful life.
- An electronic system such as seats, sound system or others are draining your battery.
What does this message mean and why am I seeing it?
- Monitor voltage of main battery G1 and auxilary G1/7 battery.
- Monitor alternator voltage at terminal 61.
- Control auxilary battery relay.
- Control on/off accessories privatization
- Control the charging of auxiliary battery
- Sets fault codes via CAN Communication and DTCs
- Sends signal to display the instrument cluster fault message.
- If there is an electronic consumer / accessories (for ex: heated seats) draining the car battery to rapidly, to stop the battery drain.
- To save the batteries for critical situations such as staring the car and keeping the engine running properly.
What should I do to solve this problem?
If you left the lights on or the radio on and then you saw this message then just leaving the car to charge is all you need to do. The first thing you should do is start the car and drive it or let it idle for at least 15 min. The BCM will allow the auxiliary battery to get a charge once the system voltage is over 13.5 Volt. It allows this one time every run cycle. Once the auxilary battery gets charged, the error message on your display should not come up on your next driving cycle. If you see the message come up more and more frequently check to see if your batteries need to be replaced.
If you have been seeing this message several times recently it is time for you to plan on replacing the batteries. Car batteries have an average life of 5 years so if your battery is old plan on replacing it.
You can get both the auxiliary battery and the main battery from Amazon and for much cheaper than the dealer. You can read reviews too to make sure to get a good battery. Replacing either one of these batteries is easy. Below are the two batteries that you will need:
If you replace the batteries and you still are having problems then you may want to check the GENUINE MERCEDES Auxiliary Battery Relay (High Current Relay) 0025424719
If you leave your car sitting for extended periods of time or would like to properly charge a dead / discharged battery you can use a trickle charger like the one below to maintain or charge a car battery properly.