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Current 2017 GLE350, 2007 S550, 2002 S430, 1998 ML320 Deceased 74 240D, 92 400E, 97 E420, 13 GLK350
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Discussion Starter #1 (Edited)
The dreaded slow battery drain is back. Just shoot me. :eek:

Replaced a weak battery 12 months ago when the '02 S430 would slow drain over the weekend, and it helped - until recently.

Now I've got an intermittent drain on my daily driver. Got a nice Black and Decker Jump pack so it hasn't let me sit - yet.

An electronic Battery test at Autozone this week showed that it was good and holding a charge after a long drive. Running voltage from the Climate Control module shows 14.0 VDC, which confirms to me that the alternator and voltage regulator are working.

All of the door windows, seats, sunroof, etc work fine.

Which makes me suspect the dreaded CANbus network problem that either CANbus will not go to sleep when the car is shut off and the doors closed.

Checked all the lights at night to ensure that no lights were left on, and removed the Navi CD for the time being.

Called up the Diagnostic errors on the Command Console, and got the following - none of which were showing as active faults:
B1010 The supply voltage of the control unit is too low (3 times)
B1762 Fault in CAN communication with A40/3n2 (Navigation processor) (1 time)
B1780 Fault in CAN communication with Instrument Cluster (5 times)

The D2B (fiberoptic network) does not show any programming mismatch shown in the photo below for the Command system.

The voltage too low is probably a symptom of the battery draining. Only one hit for the Navi processor does'nt worry me too much. 5 Hits on the Instrument Cluster makes me suspicous. However, the cluster turns off and 'goes to sleep' when the car is shut down.

Before I make a boat payment for the dealer or an indie and shovel money at them to easter egg a diagnosis, any input from the forum?

A photo of the diagnostic functions of Climate Control (battery voltage) and Command Console is shown below. As an aside, found out you can get German language titles on the Climate Control diagnostic panel by holding down both the Rest and 'O' buttons. (U-Batterie)

Thanks in advance for advice

**UPDATE - After reading so many posts about problems with slow battery drain, and suffering the same fate, thought I would dump all my lessons learned into a DIY troubleshooting guide that is attached on Post #21.

If anyone wants to add their experience to this generic guide, please post and I will revise.

Many thanks to Streetglower for getting me on the right track to solve the problem! :bowdown:
 

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Discussion Starter #2 (Edited)
No dead battery this morning - car cranked fine. However, when pulling up point 24 on the climate control it only showed 13.0 vdc with the engine running (too low). After a 5 mile trip, the battery terminal voltage on point 24 was back to 14.0 vdc. This probably means there was some battery drain over night.

Still suspect that the Controller Area Network (CAN) is not sleeping when the ignition is off. Seeing how many battery drains the forum members have, I am determined to learn this system without (hopefully) doing something like deploying an airbag, frying the Electronic Ignition Switch (EIS) or voltage spiking a Signal Aquisition Module (SAM) or CAN. I figure that is about the worst that can happen. Right? Anyone chime in before I go over a cliff. :)

Lots of battery and CAN woe on the posts. A good start on the Encyclopedia gets me going.

It appears that the W220 has two CANs - one for the engine/chasis (CAN C), and one for the interior/body (CAN B). The EIS is the gateway between the two systems. Error codes can be displayed as shown above. Since my error messages were for the interior components, I'll first focus on CAN B.

From what I can tell, CAN B has three signal busses each with two lines that plug into the controller modules (door, sunroof, instrument cluster, navigation, windows, etc.) Each of these two lines get split off to controller modules, with one signal wire being higher voltage (CAN H) and the other signal wire being lower voltage (CAN L). Mirror image signals are sent through each line at different baseline voltages. In a German redundancy mindset, if one of the two signal wires short or open, the control module will still function. However, it will likely prevent the CAN B from going to sleep, and the activity will draw down the battery. If the second signal line is open or short, then the component will not function, and potentially all of the controllers on that signal buss will be affected if there are two shorts (grounds) present on the bus network.

IMHO - a slow battery drain is a precursor of a single fault to more significant controller network problems when the second electrical fault occurs. The Germans made the W220 CAN only single fault tolerant. Imagine!

Found a link to a MB tech training manual (thanks Skylaw), which states that using techniques and voltage meter, oscilloscope, test leads, WIS and sadly a STAR DAS, these problems are easy to solve. Since I don't have $5k for DAS, going for the gold using a voltmeter and onboard diagnostic system.

Any suggestions?
 

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Zotye Auto 1.5T T600 2016
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If you use the ohm meter tester in line between negative pole and the disconnected negative cable with the car locked and boot lid open, but manually locked then the reading should drop below 0.06 ohms after about 30 mins or so.
 

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Discussion Starter #4 (Edited)
eric - any impedence requirements for this test? What will it tell me if it is unsatisfactory?

Thanks

Quote "If you use the ohm meter tester in line between negative pole and the disconnected negative cable with the car locked and boot lid open, but manually locked then the reading should drop below 0.06 ohms after about 30 mins or so.
__________________
ERIC."

12/3/10 - update - no reply from eric - but I believe he mistakenly specified a resistance reading of 'ohms' instead of a current reading of 'amps'. With that important substitution, the advice is correct. Just wanted to make sure that no one reading this thread tried to in line (series) a multimeter using a resistance reading and fry their instrument.
 

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Discussion Starter #5 (Edited)
Looked on the wide wacky web for a set of MB test leads for the CAN B bus network - No luck, so I needed to see the bus socket size to make my own test leads.

Two of the CAN B buses are under the passenger and driver side footwell next to the rocker panels. Took apart the passenger side interior (X0/34 bus) to get at the bus beneath the floormat (shown in first photo below, with a small bit of debris in bottom center of the photo inside the black wiring loom tunnel). I removed the X0/34 bus from its normal horizontal position for this photo.) Suprisingly, the bus had junk crammed into the empty sockets (see closeup with remaining junk - this is after I dumped out most of it into my palm. The last photo shows what I got out of the empty sockets before vacuuming).

Since each pin in a socket has different voltage potential (always), its a pretty good bet that even dry organic crud stuck accross the two pins of different voltage in a milliamp control system does not help the cause - particularly in high humidity Florida. Did not want to use anything metallic to get the rest out, so I used a vacuum with a plastic end. Still worried about static charge affecting the CAN B bus, but the car worked just fine afterwards. My original guess is that the small voltage potential on the CAN bus was enough to attact light dry junk into the socket well that had some static charge. There is also a ductbank that could cause air currents below the floormat. Then again, it could have been an insect.

Took apart the drivers side floormat and wiring loom to get at the opposite CAN X0/35 bus, figuring I'd find the same condition. The third photo shows that there is a seam in the carpet right above the CAN bus. This is not sealed, and where the junk leaks down. Of course, there was debris below this point, on top of the plastic roof of the wire loom, and on the metal floorpan. Inside the wire loom, more dry junk, but nothing in the horizontally mounted bus socket! I don't know why the difference in socket debris attraction since they are mirror images for setup and mounting.

Neither the CAN B X0/35 bus or the X0/34 bus have the Navigator or Instrument cluster controllers that threw error messages - those goes to the X0/36 bus under steering wheel. So, I still don't know if the X0/35 bus junk or the error messages on the X0/36 bus are related to the battery drain problem.

The work history for this car shows a dealer easter egging a dying battery problem. If they were using STAR DAS, they never would have had reason to dig around in the passenger side wire loom and find what I did.

Next step - look for suitable sockets to build test leads and do voltmeter pinout checks.
 

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W221 & Audio Moderator
2013 S550
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Before you get too much further into this - and I appreciate all the documentation you are doing - I have read that with some COMAND 2.5 nav systems, leaving the nav disc in the slot will cause the CAN bus not to shut down. Some contributors have reported that simply ejecting the nav disc resolved the problem.

A pain, and it's not supposed to be that way - but you may want to give it a try - and perhaps with your troubleshooting skills, find out why that actually happens.
 

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just by reading this it looks like you are getting to deep into diagnosis before starting with the basics. first things first are hooking a meter up to the battery and checking for an actual draw. you are checking the amperage draw of the battery. you hook the meter to the negative cable and then the other lead to the negative post. you should be seeing anywhere from 20ma-80ma depending on what options your car has. you need to see if you even have a draw before taking a guess as to whats wrong with the car. another thing is just cause the voltage reading is 14v doesnt mean the alternator is producing the full current to charge the battery. voltage and current are 2 seperate things. your alternator could be only putting out 50A which is not fully charging the battery. last thing is exactly how long before the battery goes dead??? you havent really said that the battery does go dead. i ask because alot of customers tend to leave a car parked for an extended period of time and thing that the car should just fire up with no issues.
 

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Discussion Starter #8
Skylaw - thanks for the tip. Saw the Navi CD ejection post and tried that several weeks ago, CD hasn't been installed since but the battery still drains.

Streetglower - Good advice, I'll do an amp check today with the trunk light removed and installed. (key out and doors closed)

The battery can die overnight if the car is lightly driven, rarely dies the day after my 20 mile commute. Cold engine battery voltage dips down to 10.6 vdc on climate diagnostic for pt 24 overnight. After a shutdown with a few miles driven, a warm engine for the same point reads 11.8 vdc.

You are right, I may be pre-maturely assuming a good alternator. Previous owner had dealer replace the alternator under warrenty work, I had the leap of faith that the new alt was good.
 

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I am having the exact same problem on a 2004 E320. It has been to the dealer with no success. But they have narrowed it down to the cluster fuse which is a 7.5amp fuse in the engine compartment and a 40amp fuse (#6) in the truck fuse box. I dont have the schematic to the fuse boxes. Can some one send it out. Or give some light on this matter it will be greatly appreiciated....
 

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Discussion Starter #10 (Edited)
In line ammeter test results - looks like excessive current draw. Setup - 10Amp dc ammeter in series between battery negative and chasis ground. Ran 3 tests four minute durations.

Driver door unlocked, all others locked, with trunk open between 3.5 and 4.5 amps.

Manually locking driver door drops current to 2.80 amps average.

After 2 minutes, current drops to 1.90 amps and remains unchanged next four minutes.

Third test with trunk lid open, but the trunk latch manually closed causes 2 trunk lights to extinguish (the green LED emergency release never went out).

Manually locked initial amps was 0.67 and dropped to a low of 0.45 amps after several minutes.

After 15 minutes from the final test, a check showed the amperage was still at 450 milliamps.

Restored battery terminal connection, pressed emergency trunk release to reset latch. Restoration also included reset after car start for the Instrument cluster Airmatic, ESP and BAS warning messages due to battery disconnection. (Reset is turn steering wheel full left, and full right to the stops) Will probably have to also resynchronize windows.

Bottom line - expected 60 milliamp 'sleep' current draw. Observed a 450 milliamp current draw. Car had lower current draw when all doors were locked and trunk switch closed.

I am beginning to suspect that a new battery had more capacity than its 1 year old self, and masked the problems from last year.

blairjules - Try to repost your question on the W210 forum, they will be able to help you there - this is the W220 forum for S class - the wiring layouts are different. I've got a W210 '97 E420, but it too will have a different wiring layout than your car.
 

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when you do the draw test, all doors need to be locked and trunk locked, the car needs to be as it is when you are away from it, this gives you the most acurate readings. also 4 minutes is not long enough to wait, sometimes the car wont fully go to sleep for up to 20 minutes depending on what options the car has. now if after 1q0 minutes for saw you are at 450 miliamps start pulling fuses 1 by 1 untill the draw drops to 20-80 miliamps. then with that same fuse reinstalled the draw should go back up. draws arent at all hard to diagnosis as long as its happening at the present moment. what becomes an issue is when its intermittent and trying to catch it isnt easy. at the dealer we had what is called an sd scan tool on the das which hooks up the the can network and will monitor the car for extended periods of time and when a unit wakes up it detects it and stores the info. its better then sitting and watching the meter.
 

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Discussion Starter #12 (Edited)
streetglower - good advice.

Today I repeated the current draw test, and after 45 minutes, (command unit off, doors locked, and trunk lid latch manually closed to the second position) the in-line multi meter reading did not go below 400 milliamps. (The test arraingement is shown in photo below - the negative pole clamp just provided an easy spot for the alligator clip.)

Looked up Startek website, and got a one day subscription. Nothing definitive for the S430 on this problem. There is a very cool 'On-board electrical system structure description' for the two battery chassis 164/251, 211/219, 221, 230. This contained some generic troubleshooting tips starting with streetglowers advice to measure "quiescent" (rest) current. And to Skylaw's point, this instruction directs that the CD be removed from the Navigator, and the Command unit powered down prior to starting the test. Which, after 35 minutes should be no more than 60 milliamps.

Some other tips from Startek on battery drains:
1) if after 30 minutes the quiesent current is less than 1.6 amps, but above 60 milliamps, it is probably not the CAN bus failing to go to sleep. That means an independent power consumer problem that can be found by pulling fuses and relays. Also on CAN bus troubleshooting, if a control circuit is good, then the CAN High and Low resistance should be 60 ohms with power first removed. Any isolated circuit should be 120 ohms between high and low CAN bus connections. (BTW - I am very reluctant to perform any steps that could result in a short between CAN bus high and low connections for fear of needing to reflash computer memory, or worse wind up frying components)
2) Quiesecnt current can be observed with a clamp on ammeter, or in line (like I did). Downside of in-line is that the resynchronization has to be done for windows, doors, steering stops, sunroof and low/hi beams.
3) Alternatively, if a clamp on ammeter is not available, a parallel battery can be hooked up to avoid losing synchronization. (too much trouble in my opinion)
4) The charging capacity of the alternator should be checked during this troubleshooting, and expected to be around 150 amp capacity. Because streeglower already referenced this test, I got an $10.95 tester from Bennett auto supply earlier this week. (Just have to perform the test yet.)

Today is a beautiful day in Florida, so the next steps will keep me outdoors for awhile: :D
1) Fuse pulls and ammeter checks.
2) Alternator performance checks.

Looks like I can ignore CAN bus issues for the moment.
 

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Discussion Starter #13
Eureaka! Oh crap.

With 2 hours of sunshine and patience, I am closing in on the source of the battery drain.

The good news - it is powered through 7.5 amp fuse 63 - Language Control systems/Telephone systems. Eureaka!

The bad news - leaving it out while running the car results in the TeleAid system disabled (who cares) and silences the radio sound (damn) and a constant SRS airbag dashboard warning. Oh crap.

Methodology:
1) Key out of ignition.
2) Ammeter in series with battery.
3) Trunk latch manually closed in second position (with boot open to see ammeter).
4) Hood up to access front 2 fuse boxes.
5) Passenger side rear door open to access third fuse box, with latch manually closed and and the door switch blocked in the closed position with a yellow highlighter.
6) All doors locked. (FYI - the driver door cannot be manually locked while open. Nice feature to prevent keys locked in car)
7) Copy fuse chart from owners book for a guide to markup with pens.
8) Get the fuse puller from the spare tire tool kit.
9) Methodically pull fuses and check the ammeter for changes.

I only pulled a max of three at at time (easier to keep track of for reinstallation). My methodology was to start under the hood fuse boxes. Of course, the circuit I was seeking was associated with the fuse box under the rear seat, so it was one of the last fuse series that I pulled.

I pulled three fuses at the same time f61, f62 and f63. Reason for multiple pulls is that the car sometimes responds by resequencing sleep for the CAN bus (increased amps, then step lowered). Since I did not want to wait 5 minutes for each fuse, I pulled them small groups. Once you get an understanding of the fuse chart and boxes, it is possible to restore fuses if you get lost on reinsertion.

When I got to the 61, 62, 63 fuses group, quiescent current dropped from 400 milliamps to fluxuations between 20 and 60 milliamps. Then put back each fuse one at a time until the offending circuit was identified.

The fuse chart states that f63 "Consuming Units" include 'Language Control System" and "Telephone System/emergency call." No mention of radio or SRS circuit. Oh well.

Next steps - still have to use my alternator check gadget (although I think the car is good here). Also need to find a wiring chart to further isolate the electrical fault. I'm thinking some sort of ground at this point.

Photo below shows how the passenger door switch was blocked with a highlighter (left side), tools used, and Guinness provided by my bride (2 required - beer not wives) ;)
 

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Discussion Starter #14 (Edited)
Startek turned out to be a great tool for electrical troubleshooting. Using it, was able to find that the TeleAid was component A35/8, which translates to a photo location in the car. (Never would have located it on my own.) Also found that TeleAid subassemblies include: GPS, Phone, Emergency call.

Startek also gave me all I could handle on WIS (workshop instructions) and EPC (Parts cataloge) procedures and drawings of other work that I wanted to do on the family E420.

A one day Startek subscription also gave me TeleAid related wiring diagrams, and service campaigns. None applied to my year/model, but gave me appreciation for what all this system does - for example, TeleAid ties into the DB2 fiber optic network, and signals an accident - Airbag deployment. With the TeleAid de-energized, the fiber optic network was interrupted and the cause of why the radio would not work. The SRS (airbag) warning light came on because TeleAid could not interrogate the system.

TeleAid control modules are under the rear passenger seat. In the photo below, I pulled the fiber optic network connection. Black coupler between thumb and forefinger, with a white and red light lens. (The fiber optic cable were the Orange looking 'wires' that I was careful not to bend). Just got done ordering a MB Fiber Optic Bypass Coupler Part Number 000-545-33-84, all of $8. When the part arrives, I'll use it to bypass TeleAid and get my radio back when the fuse for f63 is pulled. That will give me a clean battery quiescent current and a radio.

Not sure if I care about the constant SRS light on the instrument cluster and loss of GPS. Although the SRS light being lit all the time would mask a follow-on real fault. Just know I am not going to drop $1,000 bucks to replace all three TeleAid system modules. Since this system still works, but is always energized, another option is to install a power kill switch when the car is shutdown to get the SRS alarm light working properly.

So far I'm $98 invested into this project, have isolated the cause, and contemplating repair options.

$60 - Black and Decker jump pack (Highly recommended and shown below)
$10 - Auto alternator tester (waste of money - just a voltmeter that has less functionality than climate control feature)
$20 - One day subscription to Startek (Highly recommended, but have a whole day to review the site)
$8 - Fiber Optic Coupler
 

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Great Thead!! I had to use google search as I'm on Mbworld, not Benzworld.

I'm going through the same exact thing as you right now.

Multimeter hooked up to battery and reading the draw.

I think it was the Tow-Away Hook Relay that was killing my battery, I replaced it and began testing today my draw is .04-.07 and battery didn't die after 24 hrs.
 

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Discussion Starter #16
Gondon - sounds like you are in the clear if quiescent is down to 40 - 70 milliamp. Did you find it in a fuse by fuse pull?
 

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Gondon - sounds like you are in the clear if quiescent is down to 40 - 70 milliamp. Did you find it in a fuse by fuse pull?
No, I heard the clicking from a Relay and I pulled the Tow Away Hook because when I pushed the button on the dash it repeated that sound but who knows.

Maybe the Drain is going back on after 15-20 min..or my battery is shot after last weeks of jumping because when I get in the car it's 12.08 and supposed to hold at 12.45 I think. Maybe I'm wrong. I will do more tests as I think im off the hook a little too easy :thumbsup:
 

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Discussion Starter #18 (Edited)
Got my eight buck optical splice this week and installed it today. (Shipping cost more than the part, a MB first?) This splice allows me to permenantly pull the fuse for the TeleAid (source of battery drain) and then splice back the DB2 fiber optic ring together in order to get the radio working again.

I am not going to miss the TeleAid Navigation; my 16 year old daughter's Driod phone has better GPS than the 2002 MB software in my car. Also not gonna miss the analog telephone feature that won't work anyway, and won't miss the TeleAid since I'm not subscribed.

However, SRS light is still on with the DB2 ring splice installed. I suspected this was an electrical connector, and I am very sure that this is an indication only. When TeleAid is energized, SRS light goes out, so I am certain the safety feature for airbags still work. Down the road, I am going to have to bypass the TeleAid input to this annunicator so if there is another fault, the SRS will flash again on the instrument cluster.

Shown below are the pics for the splice. The ring is unidirectional, and the ends of the fiber are locked on with white and red lenses. They only fit one way onto the parallel connection, and are held in place with the original flat black connector and a simple mechanical clip that prys up with a screwdriver (grey rectangle). The new series connection shown does not matter for orientation. Only tools for the fiber connection were a flat head screw driver and a couple of zip ties to lay the loop out. (Gotta be careful to lay out the fiber optic cable and hold it in place as to not to kink the ol light pipes, or they won't work and require a professional splice by dealer)
 

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2012 S550 Bi-Turbo 4Matic
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Just a simple question....what kind/brand of battery do you currently have?

Seems shorter then OEM
 

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Discussion Starter #20
mugur - It is an off brand and shorter, replaced a MB battery last year.

The good news is that starts are solid every morning now that the TeleAid is bypassed.
 
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