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Opening boot with a flat battery

OPen the bonnet and remove the front right SAM unit. Attached to this unit is a large red +ive cable. Connect 12V to it and use the button on the key to open the boot.
 
locate air line to boot lock (should be under rear seat but not too sure about your model) and blow as hard as you can!
 
Solar battery charger

tromppost,

Yes,If you have no large electronics drain. (It only puts out 125Ma)
Will the Panel be mounted where it can get Sunlight 8 or 9 hours per day?
If there's no danger of it being nicked,I'd just suction cup it to the Boot lid
and run the wires (Sandwiched in between the upper and lower rubber gaskets of the boot lid opening) into the trunk and use the Alligator clips
to attach to the Battery.
If it's going to be "on it's own",I'd put the solar panel in the rear windshield
(with the suction cups) facing the prevalent sunlight and run the wires along
the top back of the rear seats,down along the c pillar underneath the seat
cushion and into the boot to the Battery.

As mentioned , the cigar lighter plug in option is a "No Go" for Mercedes, for when the key's
not turned "On or "Acc" there's no connection to the Battery.
 
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Cant see that working. If put wrong way round it will cause problems and if the correct way round might cause a problem but wont charge battery unless lights were left on as light switch would turn off power to lights, or disconnect battery from lighting circuit

Not sure that light switch in off possition would break circuit to lights as I think they'e on the CAN bus.

For example, park your car, switch lights to off position, engine off and get out of car. Now lock car. Number plate lights and side lights will stay on for xx seconds (depending on setting in cluster) even though light switch in off positon.
 
when my 2001 s class battery died i had the same problem, i used the metal key to open the drivers door and open the bonnet, on the o/s of the engine bay is a black fuse/relay box, lift the lid off and remove the top layer of fuses, there is enough spare loom to just lift it to one side, you will see a very thick red cable junction, clip the positive lead from a battery to this and the earth lead to anything metal on the body, i.e a door hinge bolt head, hey presto full power restored to enable all vehicle electrics to be operated except starting. hope this helps
 
Fitted solar panel so lets see how long it is until the car blows up! only joking.
Exposed wire should be OK..
 

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If you have a First Aid box fitted, there are 3 holes under the First Aid tray that you could run the wire through to the boot, the panel could be positioned centrally out of the way of the headrest in case it were to drop.

Dec
Edit Sorry just seen yours is an S320, was thinking of a W202 so the above may not apply to you.
 
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Fitted solar panel so lets see how long it is until the car blows up! only joking.
Exposed wire should be OK..

Can you give a link for the solar panel please? I think I might need something similar. Thanks
I presume it's like this.
 
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On most cars the cigarette lighter works only when the ignition is on so yours is likely the same so you will have to use the alternative method of crocodile clips or you could remove the crocodile clips and wire the leads directly to the battery.

I too am thinking of getting one of those, so let us know how it performs for you.

Dec
 
hope you already got it sorted but if not the key will open the boot it is stiff but the key will continue turning and open.if not remove rear seat base under there you will find the main battery cable, pierce this cable and with jump leads connect an external battery to provide power to open boot, please be careful using this method. dont forget if you have had your vehicle serviced at a main dealer you will be covered by mobilo breakdown assistance
 
OPen the bonnet and remove the front right SAM unit. Attached to this unit is a large red +ive cable. Connect 12V to it and use the button on the key to open the boot.

With all due respect to every one else...the above method is BY FAR the best way that works on the W140's. It's not just the lock that you're releasing, but the soft closure mechanism as well, mercedes rectified this on the W220, but on the W140 you do need to "live" up the power system to get access to the battery.

The "black box" that many of you will see on your W202's, 210's etc is not on the W140, but a similiar point can be found underneath the car, next to the gearbox. This is at the main housing that connects the main run of battery cable from the battery to the starter motor and off to the fuse box...

I repeat, just "using the key" doesn't work.
 
Thanks, i come and go and still read a fair bit on here but seldom reply as there seem to be many knowledgable people that have far more experience than myself!
 
Just to be sure that people are Using the Key properly in the boot lock, extract the thin key from the remote control insert it into the boot lock turn it all the way to the left then push up on the key, the boot will open if your lock is functioning properly.
 

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