can't open trunk to get to dead battery!
 

Hey guys,

I have a 1992 Mercedes 400E and as I got in the driver's seat I was greeted by a dead battery. Lights, seats, everything is dead. Well I thought I could jumpstart the car, however since the battery is completely dead the vacuum system won't open the trunk where the battery is located. Also the lock on the trunk is also broken so I can't use the keys to open the trunk from the back.

What do it do? My dad is trying to call a locksmith. Is there any way to jumpstart the car from the front instead of using the battery in the trunk?

This is pretty urgent cause I have school tomorrow, any help will be greatly appreciated!

Dead battery or inoperable vacuum system shouldn't have any impact on opening the trunk. Have you tried turning the key 180 degrees and pushing the trunk button?

Thanks for the prompt reply

Well we got the car for free from a friend and since then the key never fit into the trunk lock...we think that either there's something stuck in there or the trunk lock is different from the door lock, which I highly doubt

No comprende. So this means you've never been in the trunk, or you're saying it's locked and you used to be able to unlock it from the doors - when the battery worked.

yea exactly the only way would unlock the trunk was from the doors - when the battery worked

Hook up a trickle charger through a circuit 30 fuse under the hood.

Should be a Pos jumper terminal under the hood.

Thanks for the suggestions!

@stevebfl
How would I go about doing that?


Would you guys know where the positive terminal is under the hood? I attached a picture of the engine if you guys can point out the general area where it's located

I don't think there is a positive terminal in the engine compartment. But you could check your owner's manual under jump start to see if it's mentioned.

Right behind the right side shock tower there are a couple of ground wires
[ W/10]. Just behind them is a 6 section terminal block. { X/10-4.]

That is power distribution from the battery POS.
Go to terminal #1 [ that is direct feed Battery circuit #30 SB mentions]
Hook charger pos there and neg on block or W/10 and that will allow you to charge the battery in the trunk.

Don't ask for physical appearance b/c I am working off your chassis 124.034 schematic.

Not knowable about this car, so this might be a dumb question. Why can't you just jump the car but putting the positive of jumper cable or charger to the positive on starter from under the car and the negative on the frame or other good ground?

Not a dumb question...just no need to get under the car b/c that jumper terminal is at the power distribution strip beghng the shock tower.

..but that would also work if one did not have the terminal set-up already Factory there ........

Wow Arthur thanks for the detailed explanation. I barely know anything about cars but I think we'reheading in the right direction. Here is a picture of the right (from the driver's perspective right?) side. Do you think you can point out what I should connect the positive wire to? Thanks thanks thanks

Lift up that blue outlined cover, and you will find several holes. One of these will give you + and another one -

Ok I see the holes but how on earth do I connect such small holes to my jumper cables to my dad's car??

thank thanks thanks you guys are saving me a bunch of money

Whoa! Steve suggested a trickle charger ! Not jump starting it.

lolol ok oops...wrong page...i guess i'll go pick one up then? Does any trickle charger work for my mercedes? I was thinking about heading over to my local Kragen Auto Parts

Isn't that the 8 pin diagnostic connector? That would be X11/4 - don't think that's what Arthur was talking about. And I think Arthur may have meant X4/10 rather than X10/4.

<<Lift up that blue outlined cover, and you will find several holes. One of these will give you + and another one -
>>


Don't go NEAR those plugs with a battery charger..they are ECU Diagnostic Module ports and a 15/16 v changer can fry the modules.!!!!!!!!

The X4/10 I want you to find is just behind the ground wires in your picture, and then straight DOWN ..get a flashlite.
You want the BIG RED 8MM wire ...that is the feed wire from the BATTERY pos terminal..then use one of those ground wires for your chargers NEG..

Man...o.. man....

lots of close calls today lol...soo looking at these pictures the pos terminal would be somewhere around or below the red areas? It seems I would have to remove the two wises connected to the strut towers to get underneath it all...

don't they sell chargers now that one can plug into the cigarette lighter?

http://www.vat19.com/dvds/easy-quick-jumper-jump-start-cables.cfm

Woah (again) !

Saved you from the frying pan, and tried to throw you into the fire! I wasn't thinking, and I apologize.

Immediately after posting this, and some other drivel of mine, I noticed the post above. I think the lighter idea is good....just remember that you have to have the ignition on, for the lighter to be energized.

i'm sure they sell these locally too
http://cgi.ebay.com/ebaymotors/12V-Easy-Quick-Jumper_W0QQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247QQcategoryZ63687QQihZ011QQitemZ320232049859QQrd Z1QQsspagenameZWD1V

I see it - it's behind the black box, behind the wiring harness plug. I'm looking at a 94 but it's bound to be similar. Just look for the big red wire.

Ok when you say the black box do you mean the computer housing then behind it I do see a red wire. It's connected to a black cylinder which is then connected to a metal plate. Is that where I can connect the POS wire? I think I can make it to school tomorrow : )

AJ, there should be instructions for jump starting your car in the Owner's Manual. On models with the battery in the trunk or under the rear seat there should be a positive post/terminal under the hood for your dead battery situation.

<<I think the lighter idea is good....just remember that you have to have the ignition on, for the lighter to be energized.
>>


Don't do that either..
Turning the key ON while charging the system puts charger voltage into EVERY module in the Engine mangement systems. You do not want ANYTHING ON while you are charging the battery, specially a DEAD one..
Which is why we want the charger to go to an UNSWITCHED/DIRECT circuit #30 connection..which is the Large RED wire directly from the battery POS terminal. These terminal are what are referred to as "Allways Hot".
You do not charge a battery with the ignition key ON ..EVER !!
As I said before , look around for the Terminal block with the large RED wire on it...that is the circuit #30 terminal block X4/10 and should have other smaller distribution wires going to it.
It is shown in your schematic and it is said to be located in the right compartment behind the shock tower.

Some guys understand electricity basics and some just don't...if one thinks "Band" when we mention AC/DC on this Forum, then that is a good indicator that they might not want to be fooling around with any electrical problems...:)

NO !
That cylinder is the Filter Capacitor C2 for Noise supression of the Battery/Alternator Harness.....
..but, if you follow that red wire from that capacitor, it goes right to the 4/10 terminal block you are looking for.

I think you have to move the comp. housing assemby aside and it will be right under that.
Then look for the Large RED wire at that terminal block...[ Terminal#1-circuit 30...it is probably marked right into the plastic of the term block.]

lol yea sadly I'm the kind of guy who would have Highway to Hell come to mind when I hear that term....well followed that red wire to a box and popped of the the top. There are 4 terminals and it seems that red wire is connected to the second one (see picture) There actually two wires connected to that terminal though, a red and black one. Is this where I plug in my jumper cables? It seems it would be a bit difficult to clamp the terminal since it's kinda small and the others are so close.

but I'm gonna go check out target right now because they supposedly have the cigarette jumpers (car to car) and if not pep boys has something similar where it connects a box to the cigarette lighter which helps to jump the car.

That is it.. and for the 4th time..you do not jumper there , you hook up a home type charger there to get your bat back to charge.
See the BIG FAT Black one ??? That is direct from battery and charger pos goes there and changer neg goes to a good ground. Then let it sit overnight on the charger......
You can go get the cigar one, [ which you seem to be set on] , so I guess you do not head my warnings...you only use them if you have a cigar Lighter that is alway live and does not need the key to be ON for lighter..go reread the post.
Up to you.........I'm done with this one.

Does anyone ever read..
 

I am constantly amazed, if you run down the battery why not call Mercedes for their lifetime "Road Assist" 1800 FOR MERCEDES, FREE JUMP, BATTERY AT OVER THE COUNTER PRICE, TIRE CHANGE AND FUEL.

Peter,

It would seem to be that simple, but the problem is the trunk is locked and tumbler to the trunk lock cylinder is inoperable. There is therefore no access (even for roadside assistance) to get to the battery to jump the car.

There is an electric pump that makes the vacuum to unlock the doors and trunk, but the battery is too dead to operate the vacuum pump.


Air Jordan,

Get a basic charger from Wal-Mart, or an auto supply.
Connect the positive lead to the wire Arthur pointed out.
Connect the negative to any metal ground point on the car.
Don't try to jump start the car from under the hood!
Leave the ignition switch off while charging the battery.
Do not use a charger that plugs into the cigar lighter on your Mercedes.

Charge the battery until there is enough power to operate the vacuum pump.
Use the ignition key in the door to lock, then unlock the car using the vacuum system.

Once the vacuum system unlocks the car you can push the button and open the trunk.
Once you have access to the battery you can replace it or jump-start the car and take it somewhere to get a battery.

You are almost there!

thanks speace and arthur

sorry if i sound a bit lost but im a bit anxious cause I reaally want to get the trunk open before my dad calls AAA to fix the problem as there are some "fraternity supplies" that I don't want him to see....

I did pick up the cigarette charger but did not decide to switch on the ignition so I'll probably return it. After work though I'll go to Kragen or Pepboys and pick up a trickle/home charger and then connect it to the terminal I pointed at in the picture ( right? ). I just want to be absolutely sure or else my dad will get involved and call triple a and I'd be dead

Ah - the truth comes out. I'm sure the initial assertion, that you didn't want to miss school, was at least a partial truth.

Smokin' type???

lol i was for a little bit but i stopped cold turkey and it's been 3 solid months...it's mostly just cans and bottles in there

Well that's innocent enough.
I thought you were going to say bras, panties, " tire repair kits ", etc. :D

It is that simple, the MB tech probably knows where he can apply 12 DC to get the PSE to run and unlock the car.
The other option you have heard is the cigarette lighter charger and turn on the ignition to backfeed the power.

It's better to say nothing and appear to be an idiot, than to post, and prove it. :o
It's what I get for posting about something I don't know much about. I shall try to be more discriminate in future posts.

L,
Don't stop posting for fear of a couple of mistakes..this is a learning Forum..and I have seen you write some very good and technical remedies for fellow Benzers...
..if a posting gets corrected , it is not in disrespect ...it is for the sake of the Forum members and to help assure accuracy of the Archieves [which is where all this stuff winds up, unedited] for future posters and info searchers

OK...I know im being real annoying about this but I bought the trickle charger today and just need the green light before I do this tonight. I don't want to mess up my car like I would have with the cigarette charger. It's just weird because that terminal has two thick wires

The first picture shows how I would set it up and the second picture is of the actual trickle charger.

Yes, you have it! You could even have gotten a larger charger, say 8 - 10 amps, for quicker charging. But that one should do it overnight, if nothing is on. Just connect the red wire either under the nut you have chosen, or either of the two to the right of it. (If you look closely, you will be able to see that all three of those terminals are connected by a buss under the wire connections.) Then connect your black terminal to a convenient ground point and you should be good to go.
Good luck with it,

....to add to Richards instuctions, be sure that all devices and key is OFF when using that charger, since it is so small, you need all the power it can supply to go to the battery and not have the drain factor of any other stuff...
Once you can access the trunk , you are going to want to give the battery a good change with a larger charger [ if the battery is any good]

*EDIT note*

Sorry Richard..just noticed your post did mention everything OFF.....

Alright thanks guys for all the help. I'm gonna go do take care of it right now, wish me luck!

The battery is only 6 months old, I think it's my alternator that drained the battery overnight.

AJ, the alternator wouldn't drain the battery ... it recharges the battery when the engine is running. Check the condition of the voltage regulator brushes. (The voltage regulator attaches to the back of the alternator with two phillips head screws.) If the brushes are worn down to short stubs it's likely the voltage regulator isn't recharging the battery properly. The brushes on a new voltage regulator are approximately 3/4" long.

Well? Did you get the battery charged enough to get the trunk open?

YES...sorry I didn't get back sooner... after the night I finally got the trunk open I got tonsilitis....

I connected the trickle charger and saw the cabin lights flickering. Reopened the doors and the the trunk opened! Amazing...Scary part was when my dad came out to see the trunk (where all my 'stuff' was) open. Luckily it was dark and there wasn't enough power for the trunk light to turn on and he completely missed the "supplies" which were RIGHT next to him as he was checking out the battery. Cloose call but they're safe. Bad news is we got a new battery and that drained dead in about one day. My car has had too many problems this year and so we're probably going to sell it. As much of a burden as it is, I still love the old e series.... thanks for the help guys!

did you ever get in the trunk, if so how?