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Key not working

2K views 20 replies 7 participants last post by  55russamg 
#1 ·
Picked up my new (to me) SLK55 on Saturday.

One of the keys is perfect, the other is acting up...

It is not totally dead - it will lock / unlock the car, but only from very short range, and the red LED does not light up when any of the buttons are pressed.

It won't start the car either. If I put the key in the ignition, it does not turn, and the steering lock remains engaged.

I bought brand new Duracell batteries and fitted those this evening, and cleaned all the terminals up, but it is still the same.

Any ideas?

Thanks!
 
#2 ·
if the red light on keyfob does not light up with new batteries, it might be missing the chip/transponder in it

did it ever work? see if chip/transponder fell out when changing the batteries
 
#4 ·
and batteries are only for lock/unlock...not for starting car :D
 
#6 ·
 
#8 ·
In the removable battery holder, I think the grey part is just a sliding piece with a spring inside to latch the key together. I’m not convinced the battery holder contains one of the passive transponders shown.

The circuit board that is retained within the shell includes a coil, presumably energised from the ignition barrel in the car, and I suspect the transponder is on that board. I think it works by sending an encrypted IR signal from the key to the ignition barrel.

Mine will lock / unlock the car remotely, but with very poor range even with brand new batteries and the LED does not light. The other key has much better range and the LED lights up when a button is pressed.

When I put the ‘bad’ key in the ignition, nothing happens. It will not turn at all.

Circuit board looks fine...
 
#9 ·
it must contain a transponder
that is what talks to eis to start the car
 
#10 ·
Agree there must be a transponder in the fob, but I'm sure it's not in the removable battery holder section. Maybe the US fobs are different, as they have the PANIC button which European ones don't.

I took the working fob batteries holder out and it looks identical
 
#11 ·
true that

did u get the car from a dealer? if so, let them sort it
 
#13 ·
contact private seller...just to ask him if he ever had issues with 2nd key
 
#14 · (Edited)
I had another play with the bad key this evening. Realised that if I put it in the ignition and then press the lock button, the steering column releases and I can turn the key.

I didn’t try to start the car but I suspect it would have had I tried. Weird...

There seem to be a few UK companies that will repair the key for anything between £40 and £90 (US$40 to $90!) - has anyone used this type of service?
 
#20 ·
I got a brand new Mercedes supplied key with mine. It 'bricked' two months out of warranty. Independent specialist locksmith in N.London couldn't repair it, and I couldn't bear having only one working key, so they sold me another brand new key for £180 (I think, have to check) and programmed it while I waited. I've contemplated sending the immaculate but bricked key to one of those specialists you mention, so I'm interested to hear how you get on..... Forty quid for another working key would be a steal.

Incidentally, when my key bricked, the car was at a petrol pump with the roof down. My spare key was 15 miles away. If it hadn't been for my obliging girlfriend collecting me to retrieve my spare, the car would have needed towing, steering locked, roof down - and as you can imagine the garage owners were not happy having a pump unavailable for several hours. Accordingly, if I can get a third key working, I would secrete the skeleton key somewhere underbody, and hide the module somewhere inside the car.
 
#16 ·
Between $275 and $375 is the going rate
 
#18 ·
back them anyone could make a copy and steal your car

now, you have to prove ownership, then they rob you and make you another key but no one is stealing your car Fair trade, no? :D
 
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