'06 E55 Low battery/conven. functions disabled message - did a search - help please!
So, what say you guys? There is so much conflicting information out there. Some say it's the main battery in the trunk. Some say the aux battery under the hood. Some say it's the one under the hood but they both have to be changed in pairs. Thee are even more conflicting answers, but you get the idea.
Do I need a battery? If so which one? Where's the best place to get one, and what are their respective sizes?
Any and all help in directing me in the right direction would be greatly appreciated.
Thanks.
1) Auxilary battery going bad.
2) Main battery going bad.
3) Voltage regulator going bad.
4) Alternator itself going bad.
5) Battery control module going bad.
One occurrence of "convenience functions disabled" an "Battery" warning is not enough to make a proper diagnosis.
So check the batteries for their voltage to see if they are healthy. Check for the alternator/VR by opening the voltage screen on dash and seeing what is your voltage when car is off, and what is it when it starts. If car starts and voltage remains 12v or below, then it is your alternator/VR.
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On a side note, I have read that with some battery type issues the audio system might start acting strangely. Mine is acting up. While listening to MP3 discs in the changer, it will suddenly say "loading disc" and switch itself over to radio. It never did that before. I wonder if it's connected to the battery issue.
Once I replace the battery, I think I remember reading that I have to re-sync certain items in the car. Can anyone lead me to where I would learn how to do that?
Thanks to all!
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Youtube has videos on how to pull up the voltage display.
I've yet to "smell" a bad alternator. Just replaced the one on my '05 Chevy Duramax last week (240K miles on it, not bad) and other than not putting out anything it showed no sign of duress.




Used a Bosch unit from eBay that cost $40 and followed a couple of DIY threads.
Took me about three hours but I ran into issues with not having a deepwell 15 mm socket.
Tight quarters underneath with the car jacked up but I managed to get it done.
Drove around for about an hour afterwards and no more "Malfuntion, electrical components switched off" messages.
Used a Bosch unit from eBay that cost $40 and followed a couple of DIY threads.
Took me about three hours but I ran into issues with not having a deepwell 15 mm socket.
Tight quarters underneath with the car jacked up but I managed to get it done.
Drove around for about an hour afterwards and no more "Malfuntion, electrical components switched off" messages.




Make sure you have a deep well 15mm socket for the second nut on the passenger side.
That bolt has two nuts that have to come off to get the cover plate out - that stumped me for awhile.
The top nut on that side was 13mm and underneath was another 15mm.
Other side of the unit (towards the driver side) has one 13mm nut.
There was also a philips head screw on top to remove and then the cover plate comes off.
Three more philips head screws to remove the regulator itself and then pop in the new unit and reinstall everything in reverse order.
Not a lot of room down there and very difficult to see.
Anybody that can do this job in 20 minutes is some kind of god.
Last edited by Doug427; Feb 6, 2018 at 12:38 PM.







