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List of faults that occur after disconnecting battery...
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.
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
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.
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.
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)
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.
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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...
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!




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...




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.
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.
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.
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
Because the manual says that but perhaps I be wrong…
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
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).









