Consumer battery
 

2004 Mercedes-Benz SL 500 consumer battery in the trunk. I need to replace the consumer battery in the trunk, do I need to keep 12 V to the system via the battery cables while I replace the old battery.

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NO! Do NOT try to keep voltage on the system when changing the battery. There are only three things that are sometimes "lost" when the battery is disconnected - the radio sound settings (bass/treble, but not presets), the auto-up window function, and the steering angle sensor calibration. There are instruction in the owner's manual for resetting the windows and steering angle sensor.

Can you post the procedure for re-calibrating the window function, and the steering angle sensor? I don't have a copy of the owner's manual.

To reset the windows, lower them halfway, then raise them fully, and continue to hold the switch up for an extra 5 seconds. To recalibrate the steering angle sensor, start the engine and then turn the steering wheel fully lock to lock a few times until the "ESP Unavailable" message clears.