2000 W202 Intermittent Low Voltage - PeachParts Mercedes-Benz Forum

RobertR · #1 01-23-2006, 03:13 PM

I am having an odd electrical problem with my 2000 C280 Sport.
When driving at night with the fog lights, high beams and rear defroster on (heavy load)
and either my radar detector or cell phone plugged into the lighter I will get what I can only describe as a brown out. The BAS / ESP lights on the instrument cluster will come on and the car will sputter.
If I unplug the detector or cell phone the car will return to normal.
If I turn off the highs the car will return to normal also. It seems to happen under heavy electrical load.
The Alternator and Battery were replaced about 13 mos ago by benz. Could this be a problem with either of these parts? Also I had an intermittent problem with the heater blower fan. It worked intermittently then stopped completly. When I investigated it looked like one of the fan motor supply wires was corroded. When I replaced the wire and corrected the connnection problems the fan worked. I did notice though that some times the fan speed would change on its own. Very irratic. Could this be a clue? The fan issue was recent (3 Mos)
Since this is intermittent and the car starts ok without hesitation I am stumped on where to look.

Any help or direction would be greatly appreciated.
Thanks in advance for your help.

Rob

mbdoc · #2 01-23-2006, 03:52 PM

THAT car has an alternator rated at 115A.. Add-up the consumers

The fuel/ignition/traction systens take approx 20A as soon as you start the car..
The light bulbs each take about 5A...times 4....20A
The rear window defroster can take 25A+
The A/C system can take as upto 25A

as you can see you are at the LIMIT for power for that system!

RobertR · #3 01-23-2006, 04:20 PM

Thank you for your response. I understand what you are saying but I figured that I would have seen this problem before now as all of these systems are stock and a part of the build. Since I am close to the limit could the voltage regulator be failing? Is the regulator located in the Alternator? I would hate to deal with a breakdown. Worse if it happens with my wife and child. There will be no peace

Thx

Rob

tobybul · #4 10-30-2008, 12:28 PM

Rob, I realize this is an old thread. I was searching for an issue related to why my rear defroster (and high beam flash) does not work.

Anyway, you have probably figured this out already.. but my take on it is that you may had a bad ground somewhere. I partly agree with MBDoc's diagnosis but many of the electrical devices have relays that prevent the overload from occurring. IMO, electrical loads are diversified loads - not connected loads.