Yet another battery thread
I know often it is only the voltage regulator at fault but for $160 and reliability sake might as well replace both.
Installation was a breeze since I was changing the engine water pump at the same time. As for the fan shroud that's the first thing that comes off for most repairs/maintenance including belt replacements. It only takes 5 minutes and eliminates the progressively louder swearing when your hands get bruised and gouged repeatedly in the same spots.
I had problems with mine a couple years ago.
changed trunk battery
changed smaller battery
changed VR
changed Battery control module in trunk
changed battery relay under windshield
Beginning got the low battery convience function temp disabled. progressed to red battery code. Viola, red battery code finally went away after 5min idling. I even bought a new alternator thinking that would be my last straw to change if i still got the red battery code.
The Best of Mercedes & AMG
It was coming from the alternator.
Planned to tow it the following day to the shop but she started up. On my way there I first got the dreadful brake malfunction message.. then I got the red Battery/Alternator light. As I pulled up to the shop all the lights were coming on and the car wouldn't shift into gear.
Swapped in the new alternator and everything's perfect now.
Entire alternator melted on the inside haha.
I'm going to double-check the field wire, to make sure it's getting power before I pull the current one out. If it fries a third one, not sure what to do except try an OEM one for 250% more money and no refund from Oriellys.
Last edited by HeissRod; Feb 13, 2017 at 12:19 AM.


I have read other threads where the alternator bench tested fine, but failed under load. How do I test this? What else could be causing this?






