I have a 1990 300CE-104 motor.
At night, when I first turn on the car, the lights get dim and bright like a cycle.
It gets less noticeable when I drive it for a while.
I checked the belt tension which is good, battery is new and the alternator is
like 8 months old. I bought the rebuilt Bosch alternator from Pep Boys.
They checked out to make sure that it is not a bad alternator or battery.
Any ideas?
Thanks
Barry

[QUOTE=endeavor]I bought the rebuilt Bosch alternator from Pep Boys.
They checked out to make sure that it is not a bad alternator or battery/QUOTE]

You would have to search for awhile to find lesser quality parts/diagnostic skills than those offered at Pep Boys.

Their parts are pure junk and their techs haven't a clue.

Find a legitimate electric shop in your area and have them test the battery and alternator.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

I don't know much about this problem, but I suspect that a faulty over voltage protection relay could have this effect. Another place I would check would be the voltage regulator on the altrenator and/or the brushes of the altrenator.

__________________
Daily Driver: 02 E430 4MATIC
In the family: '03 E500 // '04 ML500 // 64 220SE

Depends on how dim and for how long...

My '91 300CE's lights dim on startup due to the air pump.