Any experiance of fault detailed below?


Asked by Apr 19, 2013 at 10:47 AM about the 2005 Mercedes-Benz C-Class

Question type: Maintenance & Repair

The battery/Alternator warning light appears intermittantly despite the battery being new and a volt meter reding shows alterntor is charging.Model is c200 cdi

9 Answers


It could be the alternator is failing or there is a loose wire somewhere. Plug in a cigarette lighter voltage gauge to check it. -- SYSTEM-Lighter-Voltmeter-Gauge-Voltage-Meter-/190819892334? pt=Motors_Car_Truck_Parts_Accessories&hash=item2c6dc07c6e&vx p=mtr

3 out of 3 people think this is helpful.

ground wire off the battery to the chassis has been comprimized through corrosion, take the black wire off polish it clean, need to pull 300 CCA's through there, also the connection to the motor block and chassis. Be sure they've got what's comin' to 'em~

2 out of 2 people think this is helpful.
John Sturman

the charging circut is controlled from the ecu on the merc as it shares the same principle as the chrysler ecus and the fault itself is where the chip for the circut is breaking down had one similar put a rectifyer circut in line and bypassed the ecu to charge the battery and pulled the bulb behind the dash

2 out of 2 people think this is helpful.

Just got my 2007 MB out of the shop yesterday. Similar problem. It took several days of testing to find problem. All test of battery and alternator were good. The shop manager decided to let the car run in idle for well over an hour - then they discovered that the regulator started to steadily reduce its output to the point where it was no longer charging the battery. Replaced the regulator and now life is good.

4 out of 4 people think this is helpful.

a 2007 Still has a voltage regulator? thought they stopped using them altogether 'round 1980, what do I know? I know that you can get a one wire alternator with regulator built-in and throw the regulator that you've got into the bin, and don't worry the one-wire job has it down~ wondering now if there is a one-wire alternator replacement to fit your buggy?


The repair ticket from MB says Voltage Regulator in Alternator. The part was $163.40 plus labor.

they should at least give you the old one if they're rookin' ya' like that~

bobkat, am giving this guru business up, I've got an oil painting career to spend time's been nice offering my help to you, one last thing on the one-wire alternator, apparently MBZ has two wire jobs- conversion.html so long bobkat.....always a fan!~

1 out of 1 people think this is helpful.

Judge Roy - its always great to hear from you. Have a good day.

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