I hope I can be helped

shegel · 11-02-2009, 03:20 AM

Hello my name is Steve. I was on a different forum but all they said was become friends with my local mechanic.... I come from the vw scene where you are your own mechanic. I have searched but I didnt see anything that matched the problem close enough. anyways the car is a 2004 E500 sport Here's my problem

on my parents dash display we get the battery symbol and the "visit workshop" They have no other problems other than this warning. The vehicle starts and runs fine. I checked the voltage at the rear main battery and it reads 14.2v. The only thing I have done differently today is, I figured out how to turn the fogs on.

They haven't had the car for very long, I didnt push the knob back in before I turned the headlights back to the auto position, if that makes a difference. They are both school teachers and saved up for a long time to buy there new used mercedes

any help is appreciated

thanks,
Steve

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ap10046 · 11-02-2009, 04:53 AM

Hi Steve,
had the same red screen and warning last week. It is most probably the small auxillary battery under the hood.This is the backup for the SBC system in our cars, not there in the post 2005 ones. Changed it and the malfunction/warning is now gone.
Hope this helps
Areez

Clinton Horn · 11-02-2009, 07:45 AM

The aux battery is located beneath the cover on the passenger side of the engine compartment near the firewall. There is a sticker that says "battery in trunk" or something similar. If you remove the lid, there is a filter for the A-C system and the battery is below. If you search this forum under aux battery you will find plenty of helpful advice. There was(is?) a recall on the alternator / voltage regulator that may also be the culprit. That may be a freebe. The aux battery is a small rec vehicle type that can be sourced from lots of places. Expect to pay about $70. You should be very careful about the installation. Grounding the positive terminal while installing is reported to cause some extensive damage. Look for a set of instructions posted by vettdrvr (screen name). They are very helpful about the sequence. Disconnecting the main battery is recommended. That requires re- programming the sunroof etc. Still, this is an easy maintenance item and has been reported as high as $400 at dealers. Good Luck

paulv · 11-02-2009, 09:27 AM

Quote:

Originally Posted by shegel

.............. I checked the voltage at the rear main battery and it reads 14.2v. ............

At 14.2 volts, it sounds like you tested the battery with the engine running. You need to test with the engine off (no charging). Shut off ignition, and turn the lights on for a couple of minutes to remove any surface charge on the battery and then shut them off -- do the test. The AGM battery should read 12.6-12.8 volts. Test the aux battery with the key off -- can't remove a surface charge. The test should read the same 12.6-12.8 volts. The aux battery is only charged when the battery control module commands it to be charged.

Regards,
paul...

shegel · 11-02-2009, 03:18 PM

paulv, I checked the voltage while the car was runing to verify that the alternator was charging. I realize that the voltage should be about 12.5-12.8 while it is off I didnt check that though and will as soon as my parents get home from school.

If I read correctly the aux battery is a 14bs. or somthing similar to that?

thanks though,

paulv · 11-02-2009, 03:46 PM

Quote:

Originally Posted by shegel

..................................
If I read correctly the aux battery is a 14bs. or somthing similar to that?

.............

Seems like a 14BS will work as others have stated -- I bought mine from the dealer a few years ago and didn't go looking for alternatives.

It is important to remove the surface charge on these (AGM) batteries before taking any test readings as I mentioned before of the numbers will be off.
Regards,
paul...

fortlaudsummer · 11-02-2009, 05:50 PM

This thread should help you..many have had this problem

Red battery message ( Visit workshop)

shegel · 11-03-2009, 11:11 AM

wow awesome. I just changed the aux battery. and the malfunction is gone. thanks a lot fortlaudsummner and paulv

11-02-2009, 04:53 AM	#2
ap10046 Member Join Date: Nov 2008 Posts: 147 Drives: W211 E240 (2.6)	Hi Steve, had the same red screen and warning last week. It is most probably the small auxillary battery under the hood.This is the backup for the SBC system in our cars, not there in the post 2005 ones. Changed it and the malfunction/warning is now gone. Hope this helps Areez __________________ E55 AMG Wannabe Foundation President!

11-02-2009, 05:50 PM	#7
fortlaudsummer Member Join Date: Dec 2008 Location: Aventura, FL Posts: 141 Drives: W211 Elegance Saloon	This thread should help you..many have had this problem Red battery message ( Visit workshop) __________________ S. Florida MB Club V-Dodici TT Associate #3

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11-02-2009, 07:45 AM	#3
Clinton Horn Member Join Date: Sep 2006 Posts: 243 Drives: 2003 E320	The aux battery is located beneath the cover on the passenger side of the engine compartment near the firewall. There is a sticker that says "battery in trunk" or something similar. If you remove the lid, there is a filter for the A-C system and the battery is below. If you search this forum under aux battery you will find plenty of helpful advice. There was(is?) a recall on the alternator / voltage regulator that may also be the culprit. That may be a freebe. The aux battery is a small rec vehicle type that can be sourced from lots of places. Expect to pay about $70. You should be very careful about the installation. Grounding the positive terminal while installing is reported to cause some extensive damage. Look for a set of instructions posted by vettdrvr (screen name). They are very helpful about the sequence. Disconnecting the main battery is recommended. That requires re- programming the sunroof etc. Still, this is an easy maintenance item and has been reported as high as $400 at dealers. Good Luck

11-02-2009, 03:18 PM	#5
shegel Newbie Join Date: Nov 2009 Location: Bonney Lake, WA Posts: 3 Drives: 2004 E500	paulv, I checked the voltage while the car was runing to verify that the alternator was charging. I realize that the voltage should be about 12.5-12.8 while it is off I didnt check that though and will as soon as my parents get home from school. If I read correctly the aux battery is a 14bs. or somthing similar to that? thanks though,

11-03-2009, 11:11 AM	#8
shegel Newbie Join Date: Nov 2009 Location: Bonney Lake, WA Posts: 3 Drives: 2004 E500	wow awesome. I just changed the aux battery. and the malfunction is gone. thanks a lot fortlaudsummner and paulv

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