Battery, Alternator or regulator
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Junior Member
Joined: Sep 2015
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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?
To me this is the alternator. But could it be a bad battery or faulty regulator?
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Joined: Jan 2016
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From: In the Shadow of the Tetons
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?
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; Jul 16, 2018 at 02:12 PM.
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Joined: Jan 2009
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From: V E G A S
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.
Replacing VR is common and easy thing to do.
