brujan

have the malfunction electrical consumers switched off warning. It came on while driving and remains on continually. I have a good main battery and new aux battery. I have just checked the alternator and it is charging quite well and keeps both batteries topped off at 14.6 V I am starting and driving in cold weather with head lights on for days now so there are no problems with the charging circut or battery.
Can any one tell me what way to look for this problem it is not as simple as a new alternator or new battery, it is something else and I just don’t know
.Thanks Bruce

vettdvr

Battery control module in the trunk attached to the battery and rear of trunk has a relay inside and the contacts fail. When this happens you experience battery going dead over night. Does your battery die overnight?

brujan

The battery is new and strong, as well the charging system is strong. This problem developed two days ago while I have been putting quite a few miles a day on the car. The battery showed 11.7V before start yesterday when I checked things out I thought that was strange. The car started ok and voltage picked up ok to normal levels. After driving the car both batts showed 14+ Volts. I wonder if all night 7hrs is long enough?
Where exactly is this relay?
Thanks loads for the help

vettdvr

The Battery Control Module is in the trunk attached to the battery. It is mounted on the rear trunk panel by the spare tire. The module has a mechanical relay inside.. (you can't see the relay unless you disassemble the module. I did on a bad one to see if the relay could be replaced) If your battery is going down overnight I suspect the relay. If your charging system is normal it will charge the battery up during the day and all will be ok until you shut down over night. You can test by doing a current draw test on the battery after all the computers shut down.

brujan

Well, I know more now, the battery dropped from a standing 12.8 V to 11.2 over the day today. The battery is draining while car is off.

The car started up ok and the voltage starts to climb so I took the car for a drive to charge the battery. After about 15 minutes the heater blower came on and went to a high speed. When I got home I stopped and restarted the car the malfunction is now gone and all is back on. One should be careful as to what they wish for, now I can’t study this failure any more unless it returns.

If it does not return I guess I should replace that BCM ?? just because what do you think?
Thanks Bruce

john0183

Could you just change the relay or you have to change the whole bcm because I am having the same problem .

brujan

That’s my question too. If I were at home I would open the BCM find relay, diagnoses it and likely fix it. I do this exact thing for a living only in the HCAC industry. You can do what you have recourses to do. Maybe someone has done this and will post step by step for you. This part is hundreds of dollars no big deal. A relay maybe $10 and a little solder.LOL

I am 1600 miles form home with my wife in the Cleveland Hospital for a while, in Cleveland Ohio. I can’t play with this thing and goof it up worse, I need to know for sure this is the bad part and then change the BCMt in a parking lot. I have no diagnostic knowledge on this system and will rely on others to finally make up my mind.
Thanks Bruce

brujan

That’s my question too. If I were at home I would open the BCM find relay, diagnoses it and likely fix it. I do this exact thing for a living only in the HCAC industry. You can do what you have recourses to do. Maybe someone has done this and will post step by step for you. This part is hundreds of dollars no big deal. A relay maybe $10 and a little solder.LOL

I am 1600 miles form home with my wife in the Cleveland Hospital for a while, in Cleveland Ohio. I can’t play with this thing and goof it up worse, I need to know for sure this is the bad part and then change the BCMt in a parking lot. I have no diagnostic knowledge on this system and will rely on others to finally make up my mind.
Thanks Bruce

brujan

That’s my question too. If I were at home I would open the BCM find relay, diagnoses it and likely fix it. I do this exact thing for a living only in the HCAC industry. You can do what you have recourses to do. Maybe some one has done this and will post step by step for you. This part is hundreds of dollars no big deal. A relay maybe $10 and a little solder.LOL

I am 1600 miles form home with my wife in the Cleveland Hospital for a while, in Cleveland Ohio. I can’t play with this thing and goof it up worse, I need to know for sure this is the bad part and then change the BCMt in a parking lot. I have no diagnostic knowledge on this system and will rely on others to finally make up my mind.
Thanks Bruce

vettdvr

You will not be able to repair the relay. But feel free to go into it and see if you can, maybe you can do better than I did. The Bosch relay is a bit hard to get to, you will have to disassemble the entire unit. Once you get it out and hold it in your hand you will be much more enlightened.

Do the amp load test on the battery with ampmeter, engine off and computers timed out. All you have to do is disconnect the neg cable on the battery connect up your amp meter, have leads long enough to reach out of the trunk, close the trunk wait 30 min then read the flow.

If you read more than about 70 mAh you have a load. Then you can go to the fuses and pull fuses to see if you can get the load down.

The fuses for the power seats, and overhead panel are in the left of the trunk.

Once you have done all this and still have power drain consider changing the BCM. If you can repair the relay please publish how you did it and show photos and part numbers so others can do the same.

brujan

Well we have made it back home and I still have a bad BCM. I keep the battery charged and all goes OK. The battery charges as I drive and will run down in about 36 hours if I don't drive car. Now that I am home at my shop I will deal with the naughty BCM. I plan to replace it and when things are running OK I am going to see if it is possible to get at and fix bad suspect relay discussed above. Can any one help me with numbers? My BCM displays the numbers A 211 540 13 45 Must the replacment be the same number or will othe numbers work that have come from a 2003 E320? I keep finding BCMs that are almost the same number from the same car and am reluctant to purchase them.

vettdvr

2115408645

brujan

Well it's not the BCM. I swapped mine with one in a friends car and nothing changed. I have found that if I pull fuse F034 in the front panel, for the drivers seat all power consumption goes away. When it is in place there is a continual 2 amp draw. Is there a known suspect component that would cause this or do I just dig further into the hunt of sources and drains?
Thanks Bruce

Plutoe

Well the good news is that without the correct tools you are getting closer. FYI there are a couple of control modules in that seat circuit----so keep digging or get a scan and you will learn the problem in five minutes!!!!

brujan

Ha, Ha, I used to fix my old 126 with a pair of fence pliers. I have been on the road with this problem for weeks and only a basic meter with me. Going at stuff this way I say is what keeps my brain alive as I get older. Guess I will have to invest in one of thoughs scanners. Bruce

Plutoe

You are correct -------it is all perspective!!

Hard to keep the doors open when you try to repair one car every two months!!

bronto60

I have a battery drain issue, 2004 E500 with 2 new batteries and a good charging system. I have the bluetooth puck in my center console, and it has worked for several years. A few months ago, I noticed that my phone stayed connected with the car hours after I arrived at home. After reading many posts on this and other forums, I have isolated the problem to the puck, or whatever the puck is plugged into. I pull the puck out of the console and just lay it near the gearshift lever so I can check the light. The blue light flashes long after the car would normally go to sleep. I can connect to the car with my phone at anytime. The puck will not go to sleep if I lock the car or not; it just continues to blink. It gets warm overnight or during the day, so I know it is pulling some juice. During the week, I get the "convenience function" warning every morning, but it normally clears during the 20 minute drive to work. The car may need a jump if I don't drive over a weekend. Recently, I can disconnect the rear battery for a few minutes, and the puck works fine for a few days , then it will go back to the flashing mode. My next move is to get in the console and disconnect the puck. I have seen other posts where bluetooth was always on, but no solutions. I need one, please.

brujan

I would unplug "puck" and try another puck it may have a stuck relay inside that does not let it drop off the buss when it should but what do I know I am unable to solve my battery drain at this point.

I have proven that my drivers seat system is styaing online and draining my battery while my car is parked. I just bought a scanner and it tells me that there are no codes or malfunctions stored on the cars computer. This is odd because not related to my big dainning problem, my SRS light is on and I get an SRS malfunction warning from the car. The dealership was not able to rat this problem out a while back but was able to charge me for the time. They said not to worry the system would work ok, the problem is likely a seat or buckle sensor. Oh how I try to remember that it was a good idea to go to the dealer and then became a bad idea with much regret afterword.
Anyhow back on subject, I am unable to get codes for any problems, so I am back to old fashion logic and hunt-and -go-seek.

I am quite good at electrical understanding while being quite bad at understanding this car. If any one knows specificaly about seat system components staying online and draining battery, I have this problem. I would like to understand the system logic between the seat system components. I could make good use of a global type schematic of what is below the source at F34 fuse. The only drawings I can find are useless pieces of drawings of the cars components that goes no where. I need a global drawing that shows all pathways, components, grounds and drains that run from fuse F34.

Does any one know of an easy way to cause a code to happen so I can see this scanner work? I don't trust it.

Thanks all for any help and also for the help that has already been given, Bruce

Plutoe

I know it's Christmas eve, however you are in way over your head(diagnostically)

1 your OBD scanner will not read the MB chassis codes---don't waste your money

2 to force a code, remove a connector from any control module, but remember your non factory scanner can not repeat can not read the MB chassis and body codes.However will read the emission related codes!!

3 complete wiring diagrams are available for your car---spend the 20 bucks and subscribe to a 24 hour subscription to startek info--- and search!!

4 factory scanners have the capability to scan the busses for keep awakes" There is even an extended bus diagnostics called SDscan which is even more fast in finding issues with bus modules bla bla bla

5 I regret that i do not beleive your dealer story as they all have factory software I described and in the proper hands is excellent in determining issues such as yours!!

brujan

Well thanks for the info it really has been helpful I would like to scan this problem if I can't track the drain. The dealer story is absolutely true! I got scanned, I got a new module replaced that was scanned as bad and the SRS light remains on. Not going back. I may look for other good sources to help me though but not that dealer. It was not over my head to find the drain and it is not over my head to see that a component of the seat system is staying on or something is telling it to stay on. Thanks Bruce

adegoke

good day have read a lot of problem on electrical consumers switched off but i don't understand how it work can u tell me d location of d relay or how it look because d two battery is ok and light is it on d dush i check d two wire bayside d alternator no current about from d battery cable, one of dose two wire one most have current but no current and i check d used no blon what can i do

Victor Torres

hi my car dies over night I changed alternator and check all battery at my local auto store they said they good but my car still dies over night

Esouders

yes please help