1) driver foot well under the steering column http://www.benzworld.org/forums/att...s/w210-e50-amg-e55-amg/129771d1180716219-please-help-me-find-obd2-port-2003.jpg

2) suggest star diagnostic, others have variable capability and success to read codes correctly

3) I'm guessing your 'small battery' voltage has reduced, common feature

 

Thanks - I will look for the connector.

 

I guarantee it is your secondary battery. Mine aux battery went out at about 50,000 miles and the same Red Visit workshop light came up on the dash. Simple replace though 5 min job. It is located under the hood in the engine bay underneath the cabin air filter housing. Which if you dont know is to the left if youre looking at the car and all the way to the back. Looks like a small square black box just unscrew the nut pop it up and the battery is right underneath it. Good luck.

 

What is a good source for a new aux battery (other than the dealer)?

 

8 seconds with the search feature. The battery is a YTX14-BS size. If you do not use that exact number
then the posts my not have the polarity on the correct side. You can get them at many places, but
one of the best ones out there is listed at the end of the thread I am posting a link to.
http://www.benzworld.org/forums/w211-e-class/1656409-back-up-battery-bad.html

 

Well - I couldn't find another source for the aux (G1/7) battery other than the dealer. At the dealer the aux battery is $140.

I haven't yet checked the voltage of the aux battery. If I put a voltmeter across the terminals will this tell me anything? If it shows 12V does this mean it is OK? Should I disconnect the battery before checking?

Thanks.

 

Sorry - I tried searching various terms but didn't come up with anything.

Thanks for the help.

 

Yes the meter will. If it is below 12.5 after having been driven it is on its way out.
If you use the battery number I posted you can get one at Advance. Autozone, Batteries Plus, Sears
and many motorcycle dealers if you need one today. It must sit on a 1-2 amp charger for 4 hours if it
is one you have to add the acid to after receiving it. Never charge on of this little batteries on a full power
car battery charger. It will boil the battery.
I would wait the couple of days for the Amazon Yuasa or find a Yuasa locally and have them add the
acid and top off the charge.

 

Noodles - thanks. I will check the voltage tonight and order the battery & charger from Amazon if it is bad.

 

I don't know how in US, but in northern Europe the accumulator voltage control program has been updated by factory. That's especially helpful if you are in location which suffers cold weather conditions, and it may improve your new battery lifetime also, who knows

 

OK - checked the aux battery last night: 11.2V. I ordered a replacement (and charger) from Amazon. Once the battery arrives and I get it charged, I will report on the results.

 

Update:

I received the battery and charger that I ordered through Amazon. Total cost about $100. Filling the electrolyte was very straightforward. Battery Tender Junior charger would only deliver 750 mA so I left it on charge for about 36 hours. When I removed the old battery it was measuring about 9.5 volts. The new one I installed checked about 13.1V when installed.

I had to re-sync the sunroof but then everything seemed to work out OK.

The status code says "No Malfunction".

So assuming that the new battery will take and hold a charge, all is well.

Thanks all for the assistance.