Serndipity

The other day I left my parking lights on overnight and found a dead car in the morning.

Was able to use the mechanical key to open the trunk and get to the battery in the trunk to jump start.

Was wondering if there is a terminal (if so where) in the engine compartment for jump starting?

midget fidger

I've seen the mechanic do something along those lines from under the hood, but I'm not too sure.

MarcusF

Ignore the numbers in this picture. The red arrow on the upper right points to a black cover with an X on it. Underneath that cover is a wire that's always hot. You can use just about anything else as a ground.

Serndipity

Many thanks MarcusF.

I thought there might be one.

My BMW had such a terminal which was covered in the owner's manual as an appropriate way to jump start a weak battery condition.

MsPauly

FINALLY!!! I found what seems to correspond to my 2003 clk 320 correctly. Does anyone know if I can attach a battery charger to the post shown in the picture?

I just need to charge the battery a little bit to pop the trunk open. THEN I can put the charger on the battery properly.

MagmaRed55

Can you pop the trunk using the mechanical key?

MsPauly

so here's the latest:

I FINALLY got power to the vehicle by following the diagram MarcusF posted. BUT I had to use ground all the way on the other side of the engine compartment for it to finally work!

STILL can't get the key to work in the trunk lock but at least I could get at the battery now to charge it!

benzrookiegirl

Can someone help pls! I have an 04 clk 320 just went this morning to start it and key doesn't turn, the steering wheel is not locked, the locks, lights nothing works seems like battery is dead. how do I properly give it a jump? I read the manual but am confused as to if I put the cables directly on the battery to another car or do I use the positive terminal next to the battery and on to my own battery itself? I appreciate any response. thanks

MagmaRed55

Although I'm unfamiliar with w209s I would say that you want to jump it with another car. Battery to battery. Or battery to jumping posts, whatever is easier.

benzrookiegirl

Thank you Magma Red. so the standard way would be fine...car battery to car battery. I will give it a try just don't want to screw up anything else. Thanks

MagmaRed55

I would attach the standard way. Just as a precaution, leave the key out of the ignition during the connecting process. Hook the jumper cables up and see if power is restored to the dash and other interior components, then try to start. Good luck!

benzrookiegirl

thanks! just tried to get into my trunk where my jumper cables are but unable to open it...great! guess i'll have learn patience and wait to get other cables thanks for your help. i'll repost when I've got it.

MagmaRed55

I'm curious to know how you made out last week, Rookie. Let us know if you need help with anything else, and welcome to the forums.

johnaresch

Thanks for the post. It worked well. But a hint for all the road warriors that are not aware of the battery location in a w208. It is in the trunk and if you can't get the trunk open with mechanical key then all you have is a 3500 pound paper weight. Jumping post to post as the one person suggested is extremely hard when you CAN"T GET TRUNK OPEN. Ugh.
Again thanks for the person with the P6 suggestion (label on black box) it is the hot line to the battery and it does allow an engine compartment jump to another battery. HOWEVER you will need to clear the ABS an BAS malfunctions and re-enter the radio code. Small price to pay to get car running. And for those who will ask, no the BAS and ABS were not malfunctioning before battery failed so completely. And when cleared they do not show a malfunction.