On-Board Voltage - Mercedes-Benz S 350 Owner's Manual

Practical advice
Troubleshooting
Problem
The key cannot be turned in the ignition
lock.
490
Possible cause/consequence
The on-board voltage is too low.
Suggested solutions
Switch off consumers that are not re-
quired, e.g. seat heating or interior light-
ing, and try to turn the key again.
If this does not work:
Check the starter battery and charge it
if necessary.
or
Jump-start the vehicle ( page 525).
or
Consult a qualified specialist workshop.