On my 2001 ML 320, the charging syst. indicator lamp on the dash lights up when I go down an incline in a parking garage, then returns to normal - unlit, during any other driving conditions. Battery is 2 years old, cables & connections are tight & clean. All cells have proper acid level. It sits tight in the box. No signs of arcing from any connections. Belt looks good. No unusual noise from the alternator. I've looked at all of the obvious possibilities-- maybe. Any ideas? Thanks

If you can connect a voltmeter & watch the voltage during the problem, YOU might find whether the problem is in the alternator or not.

Has the crankshaft damper been replaced (recall)?

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator