Ok made it through power steering issues and I think I can make it the 1200 miles back home. The car has a new battery and new starter less than 2 weeks old and today I have confirmed the charging system works.

Problem:. this morning the battery was dead down to 5 volts. Something drained it, nothing was left on. The a/c system was on but with no power I expected it off as I never turn a/c off to get out or on start up.


I opened the car with the mechanical key verifed bat voltage in trunk. I put charger on car and got it charged enought to start. AFter 15 min running and engine ON voltage was about 13.8 volts or about normal. I shut th car off and bat voltage alone was 12.6. THe car restarted. I shut it down again and put the charger on a slow charge to bring the battery up to full.

Now the issue what is killing the battery (it would be nice if defective battery but isn't) overnight. I can drive it home but overnight stay at motel will leave me stuck with no battery charger or cables.

I recognize the BCM in the trunk or seat module (don't know where it is ) could be the problem.

My service manuals are of course 1200 miles away and my data on the hard drive also 1200 miles away.

So I have no part numbers or service during the holidays.

My current plan is to disconnect the battery at each stop so it won't drain.

Is there some way I can check (I have no tool either other than base volt meter) the seat module ? by unplugging or pulling a relay? or verify the BCM in the trunk? Perhaps is something can be unplugged I can get home
after the holidays and not be in the frigid weather with a 10mm wrench disconnecting the battery. I will if necessary.

Any help would be appreciated. Thanks vettdvr

There is a repair shop in town but on my last visit I had an a/c issue and they weren't much help solving that issue either other than making my wallet lighter.

 

I have fully charged. Tonight I will leave connected and check for dead tomorrow. IF dead I will probably will disconnect every night until I get 1200 miles home. No tools here for the holidays. Which fuse panel should I look under pass floor or rear left in trunk?

 

Don't make yourself crazy trying to diagnose this on the road. First off you'll need a good multimeter just to get started... Disconnect the ground cable off the main battery in the trunk when you park at night....10mm socket or wrench, pick one up at a local auto parts store, or even WalMart. You'll have to use the key blade to lock/unlock your drivers door and trunk...but first make sure the blade works in your trunk lock before you close it!! And never lay down your keys in the trunk.. If you want to make a quick guess at the battery draw, often times the audio gateway (sound amplifier) is the culprit. Easy enough to pull the 40A fuse out from the rear fusebox on the LH side of your trunk...see if it dies overnight then..You can also pick up a 12V portable jump box to take with you on the trip...just plug it in the hotel at night, don't forget you'll need an extension cord too.

 

Why not identify what systems might be pulling the power and remove all their fuses? You can then plug them in one by one until you figure out what is causing the power loss.

 

Last night I ran a test. I manually turned off the a/c ,,, audio system,,,,and head lights to manual off. Today I will see if the battery held. If not I'll recharge it at my current location then disconnect each night until I can get it home.

I do have a multi meter today .

Guess I dont' understand which fuse panel I should check. Trunk Left side,, or under pass floor.

Is there a list of the items that can cause this issue and I could check each one indivitually.

Thanks for all the help at least I know have wrench will travel will get me home.

 

It is most likely something that is draining the battery. Have you put a meter on the battery to check to see if something is actually pulling power? Also, it could be a bad battery, new does not mean its good.

 

Can I just have boiled crawfish with Zataran's vs the salad?

Update last night I turned off the a/c and lights manually. This morning it started. Don't know if this is repeatable if a relay is sticking. I will do the fuse test but at my location this is a bit difficult.
Doing the test the trunk is open so it is pulling power. If the key is off and all other items manual off I would expect to see zero volts across an installed fuse IF current is flowing and 12 volt across if the no current is flowing. This way I can pin the fuse without pulling it from the panel.

Also the airmatic might pull power just be leaning on the car doing the test. How is the trunk light turned off?

So far so good,, it started I will leave it connected untill it dies again, and I might have some time to do the checks. I am keeping 5 yr old grandson with type I diabetes and this takes lots of very close attention and time.

 

jesus this is the blind leading the blind.

You aren't measuring volts here, you are measuring amps.

You need to connect the multimeter in series (pull one battery cable, connect multimeter to that, then the other multimeter to the other battery terminal).

Run the wires out of the trunk...you want the canbus to sleep. Close the trunk on the wires. If that won't work, there should be a pin that hits the trunk frame to shut off the light. on the 210, if you pulled it out, it would turn the light off.

At this point, give the car about 15 minutes to go to sleep. then start pulling fuses to see what the draw is. If it drops once you yank a certain fuse, then you dig deeper.

I did this with a 210, which ended up being a bad IR door sensor that caused a ~200ma draw. You want it to be like 50ma max with the canbus asleep.

 

Not exactly. You can measure voltage[drop] across a fuse to see how many amps the circuit is consuming. Easier and faster then pulling all the fuses, sometimes which will cause the CAN to wake up and slow down the process of finding the suspect circuit. But yes, the first step is to check current draw at the battery to see if there really is a problem, vs. a faulty battery...or did you leave the rear dome light on?

Page down to see the volt/amp chart:http://www.import-car.com/issue/arti...ontentid=66965

 

55Greasemonkey you are right about voltage drop across the fuse. IF there is voltage there is NO current flow, If there is no voltage then there is current flow and only series amp reading will tell how much. This can be done by pulling the fuse and then jumping through the fuse and using an ampmeter.

However for your dome light comment I will know that answer in 48 hrs. I am running a test and there is a possibility you many be 98% correct on all points, but it won't be the dome light.

This morning parked outside 22F Car started no problem after sitting overnight. I think I found the problem will know tomorrow on last test to confirm.

 

Update for how the simple becomes complex.

The Warning now for service items shut down is on continuous. The battery was 12.6 V engine off and 14.1 engine on so to me this indicated the main battery is charging. the problem still is when shut off the main battery is draining.

All items are in manual off so there is a problem. now i am forced to search out a dealer for service and will be here until repairs are made.


The car was delivered to MB dealer who responded I'm short handed for the holidays and may or not be able to look at your car this week. IF this is the case by FRI I will pick it up and play the disconnect battery drill at night. The down side is the mechanical key in the trunk sticks in the frozen ice making it very difficult to open the trunk.



Merry Christmas to all....... and drive safe next year.

After all the issues I have had this MB may not be long for my stable.

 

I offer this, for whatever it may be worth:

http://www.aa1car.com/library/battery_runs_down.htm

And I suggest this, after your problems are resolved: use a strip of emery cloth to clean your battery posts and cable ends ... make the metal shine. Reattach everything, in proper order, of course. Then spray with a liberal dose of Fluid Film to deter corrosion. Fluid Film may not "fix" many problems, but it sure can keep them from recurring. Good luck, and Happy New Year.

 

Good luck and keep us posted , hopefully the dealer has some qualified and experienced techs who can find the problem quickly!!

 

I am now beyond frustration. I took it to the dealer when they opened the doors after Christmas. No appointment of course.

Dealer response.
We are totally booked and short handed and may not be able to service your car until mid january.

Dah... I have to be back in La 1200 miles away 1/2. I really need some bullet items to check if they can do nothing to help.

My frustration now is totally over the top.

 

What city are you in now? First step is to see if you have a steady parasitic draw, and intermittent draw, or simply a bad/weak battery. You may even have a bad battery control module. Even though your battery is new, these cars do not like aftermarket batteries...The factory uses a glassmat deep cycle battery for a reason. Anyhow, first step is to measure the amp draw at your battery with the car off/locked. That requires either an amp clamp or a multimeter with 10A capacity...This isn't a good D.I.Y. project either... Sometimes the draw can be easy to find, and sometimes I have seen it take 1 or 2 days in the shop...

 

The car is in Albuquerque and the battery was installed new(IS NOT A AGM AS I REQUESTED) but a BOSCH conventional battery which was installed by the shop when the starter was replaced 4 weeks ago. Doing this problemsolving is easy for me at home but almost impossible here without my tools. I have nothing but a 10mm wrench and voltmeter and that's about it. Temps were 8 F also outside so all these conditions make it somewhat difficult which is why I took it to the dealer. Until I get home I am really restricted. At home I could take the car apart in my shop but here it is a bit like being on the side of the highway waiting for someone to stop with the correct tool.

However what I might be able to do is use a 10 A meter in series with the battery, doors closed and trunk closed and let it go to sleep to check current drain. If I find it is 2 amps where do I go next? still no manual or tools

 

Update. The dealer was not able repair the problem as he did not have the part in stock AND it is New Years week. He could get the

part but not before I needed to be backhome.

What we did confirm was 1.4 A draw when asleep

The Seat control module unplug does not reduce draw

The overhead panel disconnect does not solve the problem

The recommended change the BCM in the trunk next to the battery as their computer could not communicate with it and they believe it is defectivie.

I will have to drive home this way and plan to order this part. ABQ NM Mercedes did a spectaculair job working with me on this problem to even offer ways to get it back home.

Thanks you Mercedes of Albuquerque!

Now searching for the correct part number

 

Update. I have the car manually locked to buy pass the alarm. The battery was disconnected and brought to full charge. On Tues 4 AM i plan to connect the battery start the car and load up then drive 600+ miles without shutting the engine off. At the motel the car will be unlocked , battery disconnected and then doors / trunk manually locked. The alarm won't be armed and the battery should be good to to the next mornting. Next morning hopefully battery still going connect up start up load up then drive another 600+ miles home and park in garage disconnect the battery. When the new BCM arrives connect up then run sleep current checks.

hopefully all this will work out or i will need a tow truck ..................again.

 

Good luck, Vettdvr. I wish you the best. I gotta say ... this is a helluva note for a car as nice as our MBs.

I subscribe to several forums ... this one plus another MB forum, a Tundra forum (though I sold the Tundra 6 weeks ago), a Camry Hybrid forum, and a Porsche 911 forum. Oh ... and several Harley forums.

If you're just looking for something to give you the blues, jump onto one of these MB forums. It appears that we have the most problem plagued, but otherwise loved, cars on the road. The writers on the other forums just post about good things they're doing and how much they enjoy their vehicles and bikes. The HD forum members have a problem now and then, but they're imminently diagnosable and fixable. These MBs ... these things are rolling mysteries and puzzles. But it's my wife's car and she loves it ... therefor, it's good enough for me.

 

This MB is my wifes but after being towed in 3 weeks ago and now limping home from Christmas vacation she is talking other brands to be her car of choice. SHE REALLY dosesn't like waiting for a tow truck and she did this twice already this year.

 

Suggestion: Keep wife away from Lexus showrooms ....

 

Good suggestion I already looked at GS 350 and spoke to dealer. Then he began bragging about great serviced dept and told me I had to bring it in every 3000 for oil service. That is when I lelt. I told him I would not buy any car that had to have 3000 oil changes my MB goes 13000 miles and waste of my time 4 times a year driving 100 miles to his dealership.

So no Lexus for us in the future.

 

If oil changes are a deciding factor, then maybe you should head to the Porsche dealership: 15,000 mile oil changes.

 

Probably won't be Porsche but they are nice cars. I fully charged the car Fri and disconnected the battery. I am going out to check bat to make sure it is good and not damaged from all the times it was discharger. IF ok and alternator confirms charging I will disconnect again, top off charge and hit the road at 5 AM tomorrow for the 1200 mile drive. At night I will disconnect the battery and hopefully it will make one last start to finish the last part of the 1200 mile drive.

 

The new BCM arrived 7:30 PM Fedex. I installed the part Sunday morning and problem is solved. Thank you to all who helped get us home. I really appreciated the support on the road.