error message on dash says "Convenience Features temporarily Unavailable"
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2005 Mercedes-Benz SL500 Question: Can I replace the battery in the trunk of my SL500 by mself?
techmoe from M & M Auto Service, November 08, 2011, 04:31Technician
HI THE BATTERY IN THE TRUNK IS NOT HOLDING CHARG.
IF YOU REPL THE BATTERY YOU WILL NEEDED TO SENC THE WINDOWS AND TOP.
Answer #2webuycarnotes January 17, 2014, 12:23Rookie
I have experienced this same error message and interior system failures upon starting the SL in the morning. After driving to warmup, the message goes away and the convenience features are restored. This is caused by the trunk (convenience) battery being discharged, probably from not much driving in the winter or overuse raising and lowering the top without the car running.
Before you spend the $$$ to buy and replace this battery, check the installation date. Replace if very old, but try to charge the trunk battery (no need to disconnect it) overnight to see if it holds a charge. You can also take the car to any battery retailer, and they will load test it for you, probably free. In my case, the overnight charge did the trick, and all convenience features, including the ability to raise and lower the roof without the car running, were restored. The other blogs on this subject recommend to keep a battery trickle charger (be sure it's the kind that won't overcharge the battery)on the trunk battery during times the car is not driven extensively.
Hope my experience helps you with this. Drive on in the most over-engineered vehicle on the road. But WOW, what fun!