elMacko

GENTLEMEN:
After two weeks away from home I re-connected the rear battery (disconnected to avoid drainage) and started my 16 miles commute, experiencing a rough shifting, check engine light flashing, no radio, RPM needle moving up and down with fixed engine RPM. Upon parking checked the rear battery voltage and was 12.5 volts....so...I am still trying to find the culprit...! Anyone with the same experience?

Kind regards,
'
elMacko

cdk4219

These cars don’t enjoy this connecting and disconnecting. I disconnect both batteries in storage.

Tom Manning

You can safely disconnect both batteries - rear first, then front. Negatives first. If you do front first then back, you'll get a red warning which will go away next time you start. Disconnecting the battery shouldn't give that range of faults. This sounds like corrosion on the connectors of one of the SAM modules.

Charge the batteries and see if the problem goes away but I'd be pulling the SAMs and looking for corrosion: the one under the hood RHS can flood if the windscreen drains block up.

JettaRed

iTrader: (1)

Get yourself a Mercedes-specific scanner, not some cheap generic OBD scanner, and scan for codes. Launch Creader Elite MB, iCarsoft MB V3.0, or FOXWELL NT510 Elite Diagnostic Scanner fit for Mercedes-Benz are all under $200 on Amazon. Get one, scan, and quit guessing what is wrong. It's likely that disconnecting the battery messed things up that will recover in time. Who told you to disconnect the battery?

If you are going to not drive for a while, get a CTEK battery trickle charger, such as the . Again, don't go cheap. You are driving what was once a $100k car. Some things you can go with good quality aftermarket parts for to save money, other things you need to spend a little money on.

elMacko

Thank you guys for the help..!

I actually own a I-Carsoft MB-II. Car started running normal after few miles on the road but with a check engine light. Ran the I-carsoft and erased all codes, then ran the car for 10 miles and checked for codes. Charging system has no codes, but the consumables are offline..! That indicates to me that the rear battery may be dead.....checking it today! That AGM is only two years old..!

JettaRed

iTrader: (1)

Most batteries have a 3-year warranty, so maybe you can get a pro-rated refund if you have to replace it.

A1EK

What brand is your rear battery? Many have said this along with myself, but you simply cannot beat the original Mercedes battery. They are NOT the same as a normal VARTA despite being made by them, if you change the battery I recommend getting one. I used to get 'convenience functions not available if I left the car a few days, now if I leave my car in the coldest of winters for 3 weeks, she starts perfect with no issues, which has been for 4 years now !

elMacko

I use a Duracell AGM group 48! I took it to be tested and they told me it was OK, but I am doubtful since my radio does not turns on, even though I charged the battery, but I do not have the message that appears when the Consumers are off line..! Also got a check engine light which I am trying to find with my I-carsoft MB-II without success! I am about to put a lead acid regular battery temporarily to check what happens!

JettaRed

iTrader: (1)

That's why I recommend the iCarsoft MB V3.0. It will run through all of the modules automatically versus the MB II where you have to manually check each module.

Be aware that the CEL can be triggered by more that just an engine-related problem. Fueling, A/C, and anything that affects emissions will trigger the CEL.