Need help "Battery/Alternator visit workshop
My name is Cristian , i am from Romania and I own a C180 Sport Coupe 2001 with 210.000km.
A few days ago "undervoltage consumer defective" was shown on my display.
The deffective part that was responsable for this, voltage regulator. The component was changed. Everything was ok 14.28 and on load 13.81.
But , after a few minutes Battery/ Alternator visit workshop error appeared.
I went to an electrical specialist and everything seems to be ok. Battery status - very good, alternator status - very good.
Went to another workshop, and the same. Everything is normal. works well as it shoud but error is still there.
Any advice will be highly appreciated.
Thank you
PS.
Excuse poor language.

Then try driving the car for a few hundred Km's & see if the warning goes away.
Here's some basic info on electrical system: http://www.madelectrical.com/electri...witworks.shtml
Last edited by sinape62; May 27, 2014 at 09:09 PM.
@sinape62 : The alternator was removed from the car, when the voltage regulator was changed, and tested. It is in perfect working condition.
Last edited by Cristian Kruger; May 28, 2014 at 08:55 AM.
Al consumers on(short and long beam, heather, demisting, hazard lights, seat heather, etc) 13.67 at idleing and 13.87 at 2500 -3000 rpm.
All consumers off: 14.28 idleing and 14.45 at 2500 - 3000 rpm.
When the night came, only daskboard lights went on and the parking lights (position lights) when light switch on AUTO. On manual mode low beam works as it shoud.
Should be around 13.6 idling with no consumers, 14.x at 2k RPM.
Or the alternator is dying, but afaik the brushes and stuff are all inside the VR, so I'm not sure what could fail inside the alt itself.

Make absolutely sure that the correct VR was fitted.
Get the car onto a Star to check for Canbus faults etc.
These cars are VERY voltage fussy. Have your battery properly load tested.
Trending Topics
Exactly like yesterday. So when i leave the car over night (or for a long period of time), there is no error at the first start.
Only at a second start the problem appear.
I went today to another garage and have the car tested for alternator and battery. They are in perfect working condition.
I'll go and have a star diagnonse and see the result.
The VR is brand new, made by BOSCH like the one i have replaced. The only difference was Benz logo

Could be a faulty SAM module ?
Like it happened yesterday the light sensor stopped working when error appeared.
The Best of Mercedes & AMG
First start is normal with no errors, usualy in the morning of if i'm not usung the car for a least 6 - 8 hrs.
After that the error keeps apearing. Or "Battery/Alternator" or Consumer defective. One of them or both. There is no pattern here.
When the errors are present the light sensor is semifunctional. Only the dash and parking lights are turning on. If the errors are not present the low beam is working too.
This is the car behaviour after replacing thr VR.
Cristian
Last edited by Glyn M Ruck; Jun 21, 2014 at 02:15 PM.

It has to do with comms.
VR's must always be ordered against your VIN. As must alternators

"Alternators are not what they used to be, the difference is in the voltage regulators.
There are 3 variants:
MFR (multi function regulators)
LIN (local interconnect bus)
BSS (bit synchronous bus)
BSS and LIN are used depending on the engine ECU type
either ME2.8 or SIM4, these regulators actually communicate with the engine ecu and transfer infomation between each other, the engine ecu has control over the alternator to be able to control the torque loading for emissions requirments.
So you cannot swap an alternator with a BSS regulator with one with say a LIN bus. no communication will take place"
Last edited by Glyn M Ruck; Jun 21, 2014 at 02:07 PM.
Glyn M Ruck





