mspencer

About a month ago I get a call from the wife as she is leaving work and she says her car won't start. She said lights are dim and when she turned the key she just heard a click. I knew the battery was several years old and just assumed it went out. I go by parts store and pick up new battery and replace it. All seemed to be fine until Sunday. She goes out to car and yet a dead battery again. I jumped it off and we drove it for an hour or so and came back home. Monday morning it was dead again. I hooked up charger and battery tested fine and charged. I put ammeter on battery cable leading to the fuse block under seat behind battery and with key out and no lights on it is reading 7-8 amps. It is coming from the wire that is connected to F82. It appears that this may be feeding another fuse block. Does anyone have a schematic or know what F82 is feeding? TIA.

AsianR350

There is a fuse block on the right side of the spare tire.

mspencer

Thanks. I will check tonight and see if that is what it is feeding.

mspencer

I checked last night at it was pulling 3-4 amps with no key and everything off. I did determine that the wire I had questions about was feeding the rear fuse block. I determined that fuse 25 in the rear block was pulling about 2 amps. I think this is the radio fuse. My question now is the radio/command unit controlled by the front SAM? I disconnected the rear SAM and noticed no change in the amperage draw. Where is the front SAM located on an 06 R350?

efzauner

SAMs seem to be a popular cause for this... on my previous 08 320 it was the rear parking/proximity detector sam that was the culprit... Left me stranded at 2 am at -30C at the airport...

mspencer

One interesting thing I found out was that my wipers worked with key on in position 1(engine not running) but with the engine running they did not work. I know the fuses/relays are good because if not they wouldn't work at all. I also noticed that even when both the front and rear SAM disconnected the amperage draw was still there. I found out that the relay #63 in the rear fuse block was always energized. I pulled the relay and the fuse #25 and the amperage draw went away. Does anyone know what relay 63 controls and is it supposed to be energized all the time?

Please&thankyou

I know this is a year old, but any resolution to your question and problem?

RobR350

I just suffered a dead battery which I am putting down to winter cold and I will get a new one, but as the car tends to humm away all the time when on I am bit concerned something like this might happen as its a new car (to me)

RobR350

Updated. I have a brand new battery now, and the car still sometimes get dead battery when left a little while.

this morning was dead yet it was driven about 2 days ago.... very annoying

RobR350

hello, i want to try and do a drain test by popping fuses etc. is there a fuse box schemtaic anywhere that I can use to find out what the fuses do if I found the culprit?

Cheers
Rob

adding audio

https://www.pierrelevaillant.me/post...-r350-fuse-box

http://www.mercedesmedic.com/fuse-r-...diagram-w-251/


http://travelersunlimited.club/merce...-fuse-diagram/

https://motogurumag.com/image/XxeoGz/

test amp under driver seat , to see if condensation , moisture got inside amp and causing parasitic drain.
if yes
remove amp
dry out the seat well pan area where amp is installed too
clean off outside of amp .
open amp , clean off electrolysis white build-up off insides of amp and amp cover
thoroughly dry amp , wipe down with rubbing alcohol , to clean off any condensation mineral deposit build up.
and re-install and re test for parasitic drain ?
leave desiccant packets near obvious amp chassis moisture spot when re install to absorb moisture ?

RobR350

Thanks is it easy to access that amp? I also heard about the seat modules having issues and wanted to unplug mine to see if it stopped the parasitic drain but I couldnt get under the seat very well!

Any tips?

adding audio

basic amp access

adding audio

when doing parasitic drain test with dmm and pulling fuses while checking meter .
you will know if it is the amp or seat wiring , that is causing battery drain
because when you pull that fuse of the culprit causing the drain .
the dmm amp draw meter reading will drop down to where it supposed to be , to around .03 -.06 mili amp draw ,
telling you if it is seat or what ever fuse it is. ,, that is in the line with what is draining battery and needs fixing.
make sure all doors , hoods and trunk are closed or that pin switches for what you open are secured,
so car does not wake up and give you any false positives while doing parasitic drain test . ,

i did find this seat video
but do not know if this applies to your situation..