Ranisharma55

hi all i have a w211 e 550 4 matic 2007 . this mornign I went to work
and car was workign fine but when I came back in evening car wont open
and door wont unlock . I was not even able to open the door with the
manual key . on the wirless key the light is on and I dont think there
is a problem with the key it self . I am thinking the battrey might be
dead. I was abel to pop oen the trunk and the trunk light did not open
up making me think the battrey is dead.
1. Now does any one know how to open the car when battery is dead

2. if I pop open the trunk I guess the care trunk light should light
if there was no problem with the battery .

3. How to jump start the car ?

I am not sure how old the battrey is BUt i am guessing it might be
origional battrey so may be 10 yrs old .

please advise

also does any one know a good car shop in celveland ohio for mB

jimbo1763

I would suggest that you have the battery tested and if needed, replaced. Be very careful about trying to jump the car-there are lots of stories here about that not going well, as these cars are very sensitive to their electric system and a surge can wreak havoc on the system.

Consider calling MB Roadside Assistance from what I read. They will know what they are doing and, if needed, may be able to put a new battery in for you.

rapidoxidation

The metal key (inside the key fob) should be able to open the driver's door lock, even if the battery is completely dead. It's mechanical linkage for the metal key, not electrical. Same goes for the trunk lock. If you were able to open the trunk by the usual means (touching the button) then the battery isn't completely dead.

bbirdwell

Very important!!!
When connecting jumper cables to the battery, or when disconnecting or re-connecting the harness cables to the battery, do NOT have the key fob in the ignition switch! This is documented by Mercedes technical information. With the key fob in, the EIS energizes and voltage spikes can do very, very bad things to the circuitry in your car.

I do not know positively how Keyless-Go would be affected but personally, I kept my key fob far away from the car when I replaced the batteries.

Edit: verify your car designation. The W211.2xx should have jumper connections under the hood close to the passenger-side hood hinge; ground connection is on the shock tower and the power connection is inboard of the cabin air filter. The 211.0xx will not have jumper connections under the hood; you have to connect power to the positive post of the battery and ground to the bolt-on ground point of the Battery Control Module.

Ranisharma55

@ BBirdwell thanks for the reply . i have mb 2007 e 550 4 matic . I think it is w211 . I did jump start by connecting the jumper cabel to battery terminal . so far no error msg . I was not abel to open the driver side door with the mechanical key as battery was completely dead and I can not pop the trunk. As you said there might be a jumper connection under the hood? I will look for that.

now what do u mean by
The 211.0xx will not have jumper connections under the hood; you have to connect power to the positive post of the battery and ground to the bolt-on ground point of the Battery Control Module.

where is the ground ? please let me know . I am planning to change my battery . I think it might be the original battery in the care.

does any one know how to check the age of battery ?

Ranisharma55

Also this is a used car. Do mb road side assistance will still work for me ? How much they charge for the road side assistance ?

cetialpha5

Did the metal key work on the trunk? You have to turn it one way and then lift the trunk handle in order to open it. If you turn it and then turn it back, it won't open. So while it's turned either to the left or right, pull on the trunk handle.

I would just get a battery at Advance Auto and use one of their discount codes which you can find on retailmenot.com. I think SCW247 takes up to 30% off up to about $50. If it's the original battery, there's a date code on the terminal of the battery, usually month and year.

Ranisharma55

Thanks for the reply , I was Abel to open the trunk but now I figured out that there is an axillary battery in the car too !! why can MB keep it simple. But when My batrey was dead I was not abel to unlock the car with mechanical key . So I was not abel to pop the hood, Though I was abel to open the trunk.

Now once I jumped it Luckily I turned radio and all the lights I can and car is running and now the battery seems to work fine . I guess I left some lights on some where and why the battrey went out .

Thanks for the code , I will change both main battery and axillary battery soon .

cetialpha5

That's interesting. I didn't think the 2007 had an aux battery. That was in the 2006 which had SBC. I thought 2007 got rid of the SBC unless it's for something else.