E-Class (W211) 2003-2009

Battery, Alternator or regulator

Thread Tools
 
Search this Thread
 
Rate Thread
 
Old 07-16-2018, 11:52 AM
  #1  
Junior Member
Thread Starter
 
plasma's Avatar
 
Join Date: Sep 2015
Posts: 73
Likes: 0
Received 2 Likes on 2 Posts
2003 E320
Battery, Alternator or regulator

Started getting the consumers electronics turned off error. Also noticed AC goes into limp mode. I figured the 2 year old battery was dying. So I setup in the hud to monitor voltages. With car off, the battery is around 12.1 volts. When the car starts, it drops to ~10 volts, but quickly goes up to 11.9. After a few minutes of driving, the volts start to drop.. 11.8, 11.7 etc. once it hit 11.2, I got the red "Brake Malfunction" error accompanied by loud beeps. Stopped the car. Restart was sluggish but started. After I got home and let the car sit, the battery is back up to ~12 volts.

To me this is the alternator. But could it be a bad battery or faulty regulator?
Old 07-16-2018, 02:09 PM
  #2  
MBWorld Fanatic!
 
rapidoxidation's Avatar
 
Join Date: Jan 2016
Location: In the Shadow of the Tetons
Posts: 2,423
Received 692 Likes on 504 Posts
2013 ML350 Bluetec
As I understand it, the regulator is part of the alternator. If it was mine, I'd replace the alternator and be done with it rather than have to do the job twice (replace the regulator then replace the alternator later). I bet your battery is fine.

Charge your batteries (main and aux) so you're not placing a huge load on the new alternator once it's installed.
Edit: Your aux battery is fairly new too, right?

Last edited by rapidoxidation; 07-16-2018 at 02:12 PM.
Old 07-16-2018, 02:22 PM
  #3  
Super Member
 
mtrevelino's Avatar
 
Join Date: Jan 2010
Location: The Villages, Florida
Posts: 563
Received 31 Likes on 28 Posts
2006 E320 CDI
I say it is the regulator. Make sure you get a Bosch regulator. You may have issues with any other brand.
Mike T.
Old 07-16-2018, 06:42 PM
  #4  
MBWorld Fanatic!
 
kajtek1's Avatar
 
Join Date: Jan 2009
Location: V E G A S
Posts: 9,114
Received 1,749 Likes on 1,394 Posts
1922 Ford Model T / no OBD
When it would be good idea to calibrate the meter with reading at battery post, anything below 13V means there is no charge.
Replacing VR is common and easy thing to do.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 


You have already rated this thread Rating: Thread Rating: 0 votes,  average.

Quick Reply: Battery, Alternator or regulator



All times are GMT -4. The time now is 05:04 AM.