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Battery Died Now Key Won't Unlock Doors

121970 Views 112 Replies 25 Participants Last post by  CL55Fast
Many thanks in advance to those who can share insight into this problem.

The facts:
04 S55 AMG

My battery died a few nights ago and after I got it re-charged (jumped) my key FOB would not lock/unlock my doors from any distance further than a few inches from the IR Sensor in the door.

Pointing my key at the IR sensor on the drivers side door locks and unlocks the car as well as all the other functions like rolling down the windows etc. Additionally all the close assist of the doors functions properly.

I have replaced the battery on the key. They red light on the key FOB lights up when i hit the respective buttons.

The key worked perfectly before my car battery died.

I now get a "Key Not Recognized" message when i enter the vehicle.

What the Dealer Said:
Buy a new key for $300. They can't guarantee that it will fix the problem, but hey, having a spare key is a good idea.

Key FOBS can NOT be re-programmed.

Spend $140/hr to diagnose the problem.

Question......what is the most likely cause of this problem and what is the best way to remedy the situation?

Any and all thoughts/suggestions would be greatly appreciated!!
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I'm a little confused - need some clarification.

1) Is your key still unlocking the car via the IR sensor in the door handle?

2) Is your key unlocking the car via the RF signal when you do not use the sensor in the door handle?

3) Can you start the car with the key?

4) Did you follow the precautions on jump starting in your owner's manual? In particular, was the key in the ignition when the other car's battery was connected to yours?

5) Will your second key work?

6) If no key works, have you checked fuses that may be related to ignition? They are probably 29, 30 and 49.

7) If you have keyless go, try reprogramming the key - see How to Reprogram a Mercedes Remote | eHow.com

8) You could also try reprogramming your key (since it was originally programmed for your car; this will NOT work with a second hand key) - posts 27, 31 and 35 at http://www.benzworld.org/forums/w220-s-class/1592637-please-tell-me-ignition-key-4.html

9) If nothing works, you may have damaged your EIS (Electronic Ignition System) with improper jump starting procedures. It's expensive to replace, and requires dealer programming - so try the other things first.
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Skylaw--thanks for the reply. Here is additional information:

--The key starts the car and the car does not have any error messages other than the "Key Not Recognized."
--The car runs and works just fine other than the hastle of it not opening at a distance other than a few inches.
--The IR function of the key works, but the RF sensor does not work (ie: key wont lock/unlock if further than a few inches from the door handle).
--I do not have a spare key, but the key I do have is not a second hand key (ie Original MB Key). I will try to reprogram the key and see where that gets me.

-I did NOT have my key in the ignition when the other cars battery was connected initially, but put it in after a few seconds. I had a professional tow truck company out and I just let them handle it (and be liable) as I was in a rush. But I do not think that anything was damaged during the process especially the EIS as it operates

Again...thanks...I know it's got to be some small "electron" somewhere that's just not in sync after the jumpstart. Any other thoughts? I will try the re-programming and see if that works (and then update). Cheers!
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Please update us on results.

Still confused; the RF function should work from many feet away; it does not depend on the door handle sensor at all, but works via an antenna in the shark fin (see http://www.benzworld.org/forums/w220-s-class/1834026-w220-antenna-system-key-fob.html ). It also doesn't open or close your windows.

The IR function is the one that operates via the sensor in the door handle. It locks/unlocks and opens/closes windows.

If it is the IR that isn't working, your door handle sensor may be failing; it may have slipped out of place a bit; or, there could be a problem with the IR transmitter in your key. When I had that problem with a '00, prior work on the door handle had moved the sensor out of place and limited range - when it was put back where it belonged, it worked fine.

Also, if you have very bright sunlight on the door handle, or if the key is pointed toward a bright light, range may be decreased.

If it is the RF that isn't working, I'd suspect the key you have. You may be in the market for a new one.
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Sorry for the confusion: the IR function is the one that is NOT working. The RF function works. I am thinking that I will be in the market for a new key.
P.S Skylaw: Fast, Neat, Average...
I'm a professional ATTACK pilot myself...
Friendly, Good, Good!!

Buff pilot and Covey Fac in O-2s before law school.

If you really get ambitious, see - http://www.benzworld.org/forums/w220-s-class/1473235-convienience-close-summer-opening-fix.html - but note, not all W220s have the IR sensor on both sides. Newer ones have it only on the driver side.

And - you can test whether your key is transmitting IR very well by pointing it at a cell phone camera and pressing the unlock or lock button. Works with my key and iPhone 4! I get a strong blue flash that then fades somewhat if I hold the key down.

And since you're new to the forum - don't miss the W220 S-Class Encyclopedia sticky at the top of the main W220 forum page. It will save you time and money, somewhere, some time.

Speaking of which - negotiate the key cost. My dealer recently sold one to a good customer for $185. Another went for $215, as I recall. I happened to be behind both customers at the parts counter.
7) If you have keyless go, try reprogramming the key - see How to Reprogram a Mercedes Remote | eHow.com
Skylaw , you are brilliant !! This point saved me $$$'s :) thank you so much !!




Manano ...
Friendly, Good, Good!!

Buff pilot and Covey Fac in O-2s before law school.

If you really get ambitious, see - http://www.benzworld.org/forums/w220-s-class/1473235-convienience-close-summer-opening-fix.html - but note, not all W220s have the IR sensor on both sides. Newer ones have it only on the driver side.

And - you can test whether your key is transmitting IR very well by pointing it at a cell phone camera and pressing the unlock or lock button. Works with my key and iPhone 4! I get a strong blue flash that then fades somewhat if I hold the key down.

And since you're new to the forum - don't miss the W220 S-Class Encyclopedia sticky at the top of the main W220 forum page. It will save you time and money, somewhere, some time.

Speaking of which - negotiate the key cost. My dealer recently sold one to a good customer for $185. Another went for $215, as I recall. I happened to be behind both customers at the parts counter.
Even I did not know this, so thanks for that;

How to Reprogram an Audi Key
How to Reprogram a Car Remote

Print this article

Instructions

1

Place your key in the car's ignition and turn the key two clicks to the "On" position for any Mercedes car.
2

Press and release the lock button on your Mercedes keyless remote.
3

Press and hold the unlock button on your remote.
4

Press the lock button on your remote five times consecutively, while the unlock button is still held, at one or two second intervals.
5

Release the two buttons and wait five seconds after pressing the lock button for the fifth time. Press either the lock or unlock button once to finish the programming sequence.


Read more: How to Reprogram a Mercedes Remote | eHow.com How to Reprogram a Mercedes Remote | eHow.com
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Battery Died Now Key Won't Unlock Doors from a distance

Thanks to jetfuel79, and skylaw , i learned a lot. I have the same problem when my battery died. No unusual messages were received, But both original keys stopped working from a distance. I like to ask jetfuel79, or anyone can answer, how can i solve this problem. Thank you
Thanks to jetfuel79, and skylaw , i learned a lot. I have the same problem when my battery died. No unusual messages were received, But both original keys stopped working from a distance. I like to ask jetfuel79, or anyone can answer, how can i solve this problem. Thank you
Just a few more ?'s before we/I can help

From a distance, does that mean they work when you're near?

What's the weather like where you are? Is it cold?
As Gabby06721 has alluded to there are some climate conditions that may affect the IR function of the key. As far as what can be done if it's not the weather, unfortunately the answer is little to nothing. If you have a trusted Independent mechanic than he MAY be able to re-program the key using some special functions of STAR. However, make sure that you HAVE A SPARE FUNCTIONING KEY in the event that the re-programming destroys the code in the key.

Assuming that no components died/broke when your battery drained, the best way to resolve your issue is to go to the (gulp) dealer and fork out the money for a new key. Just remember that when you do go to the dealer you will be required to show proof of ownership etc. of the vehicle so have such things as registration, insurance card, and your valid state ID with you.

Sorry to be the bearer of bad news, it's just the way it is with this issue.
Even I did not know this, so thanks for that;

How to Reprogram an Audi Key
How to Reprogram a Car Remote
Very interesting procedure.

To clarify - this is applicable only to Keyless Go remotes, right?
Hi,

Any updates to what fix this issue? My battery died and I have the same problem.

Thanks,
Very interesting procedure.

To clarify - this is applicable only to Keyless Go remotes, right?
I do not know, I have not had the chance to try it myself yet.
Hi,

Any updates to what fix this issue? My battery died and I have the same problem.

Thanks,
The benz local dealer recommends changing the antenna for the remote locking system.

estimate for repair was $2000+
Did that fix the problem or you haven't done it yet?
Merry Christmas to all!:)
Out of curiosity, have you folks attempted to reprogram your keys before going to the Dealership or replacing the antenna? The information provided by Skylaw and Eric appear to be clear and a very easy procedure to execute. I would at least attempt that before spending money on parts. However it is Christmas and it would be a very pleasant gift if it did work for you.:)
I'm shocked and frustrated, why dealers are taking advantage of a small key programming problem that can be fixed in seconds. why? because they can .. a well respected and professional dealership would find the right solution and would not use a programming glitch to generate unnecessary costly work. Shame...shame..shame...
2
I'm shocked and frustrated, why dealers are taking advantage of a small key programming problem that can be fixed in seconds. why? because they can .. a well respected and professional dealership would find the right solution and would not use a programming glitch to generate unnecessary costly work. Shame...shame..shame...
For my vehicle, the remote does not work from more than 5 inches away from the infrared but it does work when it is right next to the infrared on the handle

i have not tried key reprogram yet

JD: I have not fixed or attempted key reprogram

I also found this thread that seems helpful.
http://www.benzworld.org/forums/w220-s-class/1651484-headliner-removal-fix-remote-rf-locking.html

I must admit, I still need to read more about RF vs IR. I think right now I have them confused.

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