MB-BOB

I did a search for a member to run down some answers to specific faults that occurred when a repair station disconnected his battery to work on his car. I found in the search that there are a variety of faults... no real pattern to report.

Everyone who keeps their car long enough will eventually have to disconnect an old battery to replace it with a new one. Given the emergency nature of dead batteries when you least expect it, a dealer with expertise may not always be handy, either. So, it would probably help to identify what can happen, and the fixes you have found to correct them.

If we get enough responses to these, I will make this a sticky thread so all of us can find it in the future. So please share your experiences here. Thanks.

Saprissa

i don't have the specific fault codes that DAS would tell you,
but the main complaints I hear from noobies after re-connecting a battery is
re-sync of the windows & sunroof / panoroofs.

maybe Dean (Scorchie), Steve (MBenzNL), & Sunil (SunMan) could shed some more light on what really happens when you disconnect the battery.....

Carlos

Saprissa@aol.com

gmzc320

Hello to everyone, I have a 2001 c320 with 60k miles, and everything seems to be working very well, but in some workshop they disconnect the battery to removed it from its place, so when they reconnected and start the engine, some faults came out in the MFD

ESP not available, but this one came off a few minutes before
Display Faulty, the gas gage doesn’t work
The trunk won’t open
And the fuel filler flap doesn’t lock.

Some people think that maybe problems with the computer and need to be reset, y really don’t know what to do, and I also don’t have a MB dealer near my city, I appreciate any help if any of you know about this problem.

Tishers

You could go buy a 12 V Gel Cell battery. Somewhere between 5-10 A/Hr, then temporarily attach the gel-cell across the existing battery (in a way that you can remove the main battery without glitching the power).

Pull out the old battery, be careful not to short out the leads (since they are now energized by our temporary battery). Put the new main battery in, tighten down the posts and remove the temporary battery.

You cannot leave the two batteries hooked up for a long time in parallel. Two different styles of batteries, one is going to discharge the other (talking about hours here).

We do this when changing out a power supply or backup battery on a critical piece of process control equipment. A electric generating plant, water plant or refinery cannot afford to have equipment "glitched".

This should energize the quiescent power demands of your electronics long enough to make the battery change out.

Definitely do not run auto electronics, radios, lights, etc... during this process. The small battery is only trying to run the electronics for a few minutes.

pookie

after disconnecting the battery, i recieved the following errors:

ESP, ABS (and i think one more thing, but do not recall)

all errors were fixed by turning the steering wheel all the way to the left then right (or right to left, i forgot. try both)

vadim

Bob, a proposed sticky on this subject should consist of just one sentence (or, rather, a single word): RTFM. It is all there.

gmzc320

I resently check what else was not working, and also de turn singals, the courtesy lights, and the hazard warning lamps, I think that this is a mayor problem.

gmzc320

hi vadim, i read my manual and it dosent say anything about this kind of fault.

MB-BOB

Just call me lazy... I frankly don't have the time to merge all the previous threads on this topic. I agree the manual is a good document, but some of the errors I see in the many threads here on the subject are not addressed in the manual.

CitronC230K_03

yeah i disconnected my battery once, with the pano roof open.

i had to crank it shut then resync it. PITA!

Diz382Benz

my 2002 with 72,000 miles.

Disconnected to replace battery,

ESP Not working
SRS Not working
Windows didn't do the one touch open close.
Pano roof no open.

Very, Very bad.

XZACM102

Several weeks ago I had the same problem with my car and I was told that it happens very often when you disconnect the battery. You must take it to your dealer because the damaged electronics control unit in the trunk needs to be replaced and programmed again. Make the one who did this to you responsible. In my case I did not pay the price.

vadim

Disconnecting the battery should be safe for all electronic components. What most people think is a disaster is in fact a simple loss of synchronization - this is certainly mentioned in the manual which also explains how to get things back to normal. Blown fuses (although not very likely) could be another issue - this can be checked by the user as well. As a matter of fact, when something stops working (i.e. lights, blinkers, power seats, horn, etc.), the fuse box is the first thing to check.

gmzc320

To all of you how have help me in this problem, you were totally right this was a problem on the “Rear SAM unit”, I went to the MD dealer and bought it for $320, I installed my self. you just have to be very sure to disconnect the battery, and disconnect the ground cable first and connected last, put your key on the starter in position 0 and everything should work fine… like in the manual says.


The gas gage doesn’t work but this was because a short circuit on the measure unit, it needs to be chance.

and for all of you that in a future you will chance your battery, yo need to disconnect it like in the manual says.... remember... disconnect the battery wrong and you will have this problem...

HoustonC230

Needing to re-synch the windows/pano roof is normal (instructions in the manual). I've disconnected my battery countless times, never had a problem with the rear-sam.

I always disconnect the negative first though, as you should for any car. Not sure how this would affect the rear-sam, but for $320, I'd say it's something you don't want to chance!

benzmodz

Anyone who disconnects the battery is asking for trouble. NEVER put the key inside the ignition when connecting.

benzmodz

The big red plastic cap marked [+] flips up and accepts a second jump start battery - the ground is obviously any good contact point on the chassis. This removes the magic trick of trying to keep the new cables on the old terminals whilst throwing around a huge acid cell.

It is not the removal that kills the rear sam but rather the insertion. The best information I have is that the rear SAM power input cable (very large connection with thick red cable) is the best cable to remove from the rear SAM prior to attaching battery again. The surge is the one that goes from 0 -> 12V.

The only 2 caveats are that
----------------------------
1. Early W203 SAM modules die when powered down

2. Inserted keys blow the rear sam in 100% of all new battery installs.

Keeping the car alive is by far the best insurance but be aware that a 2 battery system can not be safely installed for longer than the shortest possible time in which one battery can be safely removed.

The prospect of reverse polarity applies to any battery in a circuit with a second battery of a different potential. That can only lead to one battery getting very warm / hot.

The workshop specified systems have a true power controller for the second battery (keep alive unit). Some workshops actually use a battery charger and not any kind of battery at all.

pookie

just out of curiosity, did you have other symptoms not mentioned. for example, did you have trouble cranking the car? or even have the warning 'check battery/alternator'?

JW001

Hi Folks,

I got an ESP Off message and then an ABS error message. They both went away after turning on and off the car 5 to 6 times. I brought it in to the dealer and the following was what they wrote up.

"Steering angle sensor faulty not initializing. SDS test found hard code C1174. Ran non-time for testing. actual valuues test found movement of steering wheel readings would go from one end of range -533.5 to +533.7 the other way. But no initialization. R&R steering wheel and driver airbag. R&R steering angle sensor. Tested wires Pins 3, 2 found 12.5V OK. Tested wires pins 3,4 found 12.2V OK. Installed new steering angle sensor. Performed initialization of steering angle sensor found OK. Erased codes and retested. ESP light off. OK."

Replaced sender unit part # 022-542-19-18.

Also, my xenon auto-leveling was screwy. The dealer had to replace right front HRA sensor on sway bar (sender unit # 010-542-77-17).

For those of you thinking of disconnecting your battery, I would definately think it through what you need to do before hand.

John

gmzc320

Well the gas gage was not working because a programming issue, I wnet to the MB dealer and they programmed it, all seams to be working well, so my question is, when you disconnect and connect the battery you should let the electric key inside in the ignition switch or not?
Because the manual says that but perhaps I be wrong…

mleskovar

"When removing and connecting the battery, always make sure that all electical consumers are off and the electronic key is in starter switch position 0." This is not clear at all...since just inserting the key activates unlocking the steering...correct? If you had the key in, removed the battery, then installed a new one the steering interlocks would operated as soon as the battery was connected. I would keep the key removed for the whole process. TFM goes on to say windows, headrests, sunroof, and ESP need resynching and clock needs setting.

M@nticore

yo, for the ESP, just turn your steering wheel full lock from left to right as for the windows & roof, just stand outside of your vehicle at the drivers door, aim your infra red remote at the red receiver on the door handle, the press and hold the open button, after all the windows(inc roof) has opened keep on pressing the remote button for about 5 - 10 seconds, then do the same with the lock button, press untill all windows are closed(inc roof) hold for further 5 - 10 seconds and your windows will also be sorted.

cntlaw

I like to support this list.
The following problems happened after the battery disconnected:-
1. Folding mirrors no longer folded automatically after the car is locked as it always does before changed the battery.
2. One of the bi-xenon headlamps started to blink and even off and on intermittently'.
3. Parking assitant - folding mirror angle faces downward when in reverse gear - this feature also vanished ( even the menu setting is correct )
but the dealer managed to resume this feature

My MB dealer told me , last week they could not fix above 1 and 2 problems until they can replace a signals processing circuit which takes at least a week to deliver.

Will keep you posted.

cnt

SUNILP

having a ESP and ABS light is normal after disconnecting the battery as the car does not remember the position of the steering wheel. After replacing the battery, turn the wheel full clock left and then right 2-3 times and the error will go away. You do not need to change the steering angle sensor.

MB-BOB

You may have to resync the Climate Control stepper motors.

Press the defrost button and recirc. button at the same time... The flappers should cycle for up to 30 seconds then stop. if they keep flashing for an extended period of time it means they cant all normalize due to a faulty stepper motor or linkage (usually the latter). Pressing the button will usually work if you just replaced the battery or something yourself and dont have access to a SDS (and all your motors/linkages are fine).