Mercedes-Benz Forum banner

After market Key Fob?

614 Views 10 Replies 4 Participants Last post by  RadoBenz77
05 S430 4matic.
Just picked up my first BenZ with known Key issues .
I just realized (while trying to figure out a possible PSE issue ) that my key does not have the red light battery bubble or infrared end!
From all the pics I’ve seen it should have those . And all the after market pics do not. So now I have to assume it’s an aftermarket key ???
Is the only way to program an aftermarket key at the dealer or someone with a Star system ? I’ve read after market cheaper keys the dealer won’t touch . It does however start the car and if an aftermarket it has the correct key blade . So now I’m Stumped on several issues .
Thanks for any replies !
1 - 11 of 11 Posts

· Registered
Too many to list
Joined
·
11,843 Posts
I would just get a replacement blade directly from the dealer, they are very cheap. If you want another key fob also get it directly from the dealer, they will program it and make sure it works before charging you. It is very likely your car may have had the theft relevant parts swapped out from a different donor car, and if you don’t know the whole history of your car it would be very difficult to get another key made
 

· Registered
Joined
·
16 Posts
Discussion Starter · #3 ·
Hi and yea the new blade is about $100.
Have to fix the PSE pump issues first as getting a new fob will be useless unless the system is functioning. What about the key fob itself ? Shouldn’t the original or any 2005 key have the red bubble battery Check on it ?
Thanks!
 

· Registered
2003 S500 2007 GL450
Joined
·
4,029 Posts
The standard EIS and key fob will not function without the IR window on the end - that is how the EIS and fob exchange information to operate the EIS.

I have had six Mercedes key fobs, and have no idea what the "red light battery bubble" is.


The Mercedes W220 key fob is a complex device. To the best of my knowledge, these are its functions:

To operate the Electronic Ignition System (EIS), both the fob and the EIS contain inductive power coils. When you insert the fob, the EIS inductively powers the fob, and requests the security info thru the IR window. The fob responds the same way, and the EIS unlocks the slot. The fob battery (or batteries) are not involved at all.

To lock/unlock the car, the fob sends RF info to the rear window antenna, and from there to one of the main computers for security validation, and that computer turns the alarm system on/off and signals the PSE control unit to power up and activate the proper solenoid valves to apply positive or negative air pressure to perform the requested operations. The fob battery powers the fob's RF system.

An option enables the fob to send an IR signal from the end of the fob to a small IR window on one of the front outside door handles, using the fob's battery. This IR signal activates one of the main computers, which checks the security info, then activates/deactivates the alarm system, tells the PSE system to lock/unlock doors, trunk and fuel door, tells the sunroof to open/close, rolls all windows down/up, and activates the fans in the driver's seat (if equipped).

Pushing the alarm button on the fob sends an RF signal thru the rear antenna to a computer which checks security info, then activates the alarm system in the left front fender well, sounding the alarm horn.

The fob contains a metal blade key that can lock/unlock front doors, trunk and glovebox. It does not activate/deactivate the alarm, nor lock/unlock the rear doors and fuel door.

It might be possible to purchase an aftermarket key - but I doubt it. In days gone by, the dealerships had a complex system to allow them to program new blank key fobs. I do not believe that the Mercedes dealership can now program you a new key fob, and AFAIK, all key fobs are now programmed in Dallas Texas. It might be possible that an old locksmith operation still has the twenty-five year-old programming system.

I have had key fobs made/programmed for two different W220 cars. The first one was $238, including the metal blade. The second, a few years later, was about $260. The price for a fob, blade and programming varies greatly at different dealerships, so it pays to shop around. You will have to visit the dealership twice - once to prove that you own the car and to pay, and the second time to have all functions of the keys tested before delivery.
 

· Registered
Too many to list
Joined
·
11,843 Posts
Dude forget about buying an aftermarket key, Mercedes will only sell and program their own keys that you buy from the dealership. We are not just talking about the key blade, we are talking about the actual key fob which needs to be programmed by Mercedes at the central Dallas programming center, not even an individual dealership can do it.

The fob has two completely separate functions, one to communicate with the antitheft system and start the car, and one to operate the power locks and trunk. Those are two separate systems within the key. It sounds like your key will start the car, but won’t operate the locks and trunk, but that’s due to your failed PSE system. Once you repair the PSE system properly, only then can you see whether your fob will operate the power locks and trunk

You cannot buy a used key online, you cannot buy a new replacement key online that will actually work ; unless you just want it for the shell if you’ve cracked your factory key.

The aftermarket key is absolutely useless unless you happen to know one of the few locksmiths with the expensive programming tools
 

· Registered
Joined
·
16 Posts
Discussion Starter · #6 ·
Yes I understand all of that (keys only at dealer) as I’m an avid BMW and Audi owner for decades . I’m just trying to solve a few mysteries about this vehicle as I bought it knowing the key fob didn’t work on the doors (remote ) and the lock and PSE functions were inoperable. Many of the Mercedes keys I’ve seen have the small red bubble on the top left indicator that the battery is working . Mine does not . So I’m not sure if this is a thing for that year or many years or the PO somehow has had an aftermarket key fob made ??? Sounds extremely difficult if not impossible but I’m trying to narrow down the issues .
‘see pic of MB keys and then mine .
Thanks !
Car alarm Watch Automotive lighting Gesture Finger

Car alarm Peripheral Input device Finger Cable
 

· Moderator
2000 S430, 2000 S500, 2003 S600 TT, 2005 E320 CDI, 2006 S500 4Matic, and 2006 S350
Joined
·
7,724 Posts
I get it now. He's referring to the red LED on the older, all-black keys. The new, chrome-framed keys don't have that LED, so it looks like you've got Genuine-MB keys there.
 

· Registered
Joined
·
16 Posts
Discussion Starter · #8 ·
Yes sir ! Was testing the PSE lines today and I heard a huge pop . Now the drivers door rear is locked closed . The button pulls up and down but the inside and outside handles only pull half way . Seems I’ve blown the door soft close actuator . Not sure , After reading a ton here , what else it could be .
 

· Registered
Joined
·
16 Posts
Discussion Starter · #10 ·
The plastic door lock vaccuum actuator broke

very common

View attachment 2794114
Hey Thanks for the reply ! Yea weird I drove the car last night and when I got to my destination the damn door now works ! I was testing the lines via pressure and heard a pop . Have to go back out and look tomorrow (freezing ass snow yesterday ) and trace the line . According to the box layout on the “how to posts” here I may have blown the seat back release instead as those are on opposite parallel ports … I posted earlier about the intake filter but didn’t get a response . Has anyone checked this to see if it’s clogged ? Looks like it’s behind the rear seat drivers side somewhere ?
Thanks
 
1 - 11 of 11 Posts
Top