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2001 SLK230
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Discussion Starter · #1 ·
I don’t use the central locking usually but when I pulled in to the petrol station the other day I found I couldn’t unlock the petrol cap.
i now know there is an emergency release.
when I got home I tried my spare key and it works so assumed it was just a flat battery. I changed the batteries and it still didn’t work and, to be sure, bought some new batteries but still nothing.
any ideas?

Thanks
 

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2002 SLK320
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So it works, but intermittent?

The petrol cap lock is operated by air/vacuum pump (PSE), like the rest of the locks. If you remove the right side boot cover, you'll see all the yellow hoses going to the pump. The one for the petrol cap is the only one going to the rear right fender.

I'm not sure if the fuel door lock it is on a separate output from the pump or not (there are 5 locks but only 3 outputs), so I'd guess I could be either the PSE being wonky, or just an air leak.
 

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Discussion Starter · #3 ·
So it works, but intermittent?

The petrol cap lock is operated by air/vacuum pump (PSE), like the rest of the locks. If you remove the right side boot cover, you'll see all the yellow hoses going to the pump. The one for the petrol cap is the only one going to the rear right fender.

I'm not sure if the fuel door lock it is on a separate output from the pump or not (there are 5 locks but only 3 outputs), so I'd guess I could be either the PSE being wonky, or just an air leak.
No, it works with my spare key but not the original.
The key is the problem not the petrol cap.
Thanks.
 

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Ah, OK, now I get it. The remote key does not work at all? It does not unlock any door, not just the fuel flap? Sorry, I got confused there :)

If so, probably just needs to re-sync. Press the unlock button twice and turn on the ignition for a few seconds. It should fix itself.
 

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Discussion Starter · #5 ·
Ah, OK, now I get it. The remote key does not work at all? It does not unlock any door, not just the fuel flap?

If so, probably just needs to re-sync. Press the unlock button twice and turn on the ignition for a few seconds. It should fix itself.
I’ll try that later.
many thanks for your help.
 

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**Premium Member '02 R170 SLK V8 5.0 & '00 SLK320
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If so, probably just needs to re-sync.
Re Synch is not possible on RF Keys, the PCB is dead. New one from MB is the only way.

Re Synch procedure stated in Drivers Handbooks and elsewhere only applies to the very very early Cars that used IR Remotes ;)

So rare I've never ever seen one in all my years working on these Cars ;)
 
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Discussion Starter · #7 ·
Re Synch is not possible on RF Keys, the PCB is dead. New one from MB is the only way.

Re Synch procedure stated in Drivers Handbooks and elsewhere only applies to the very very early Cars that used IR Remotes ;)

So rare I've never ever seen one in all my years working on these Cars ;)
That’s a bit of a bugger, isn’t it?
Thanks Dave.
 

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Re Synch is not possible on RF Keys, the PCB is dead. New one from MB is the only way.

Re Synch procedure stated in Drivers Handbooks and elsewhere only applies to the very very early Cars that used IR Remotes ;)

So rare I've never ever seen one in all my years working on these Cars ;)
Are you really sure about that? I vividly remember having to sync my remote after repair.

And having a rolling code RF fob that never needs any syncing goes against everything I know about rolling code RF fobs. But I'll admit I do not know that much :confused:
 

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**Premium Member '02 R170 SLK V8 5.0 & '00 SLK320
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isn’t it?
Yes it is, I have tried everything in the book to be able to use a used key Fob, just maybe an Auto Locksmith could do it by altering the codes in the Fob, which means unsoldering a small chip and reading the hex ................ @Deplore ?????????????
 
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**Premium Member '02 R170 SLK V8 5.0 & '00 SLK320
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Are you really sure about that?
Yes, absolutely 100% sure if you are talking UK R170 and RF Keys.
There isn't even a procedure for this on fully unlocked SDS Machine !!

IR was only fitted to very early (1996 and poss 1997 Models) ................

Disclaimer ............... Unless of course it varied in different territories, and also remember I am talking about synching a second hand Key PCB that came from a different Car, not your own Cars fob that has been repaired !!
 
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**Premium Member '02 R170 SLK V8 5.0 & '00 SLK320
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having a rolling code RF fob that never needs any syncing goes against everything I know about rolling code RF fobs.
Mercedes did not use rolling codes on vehicles prior to at least 2008 Model Year ;)

/\ /\ /\ Ignore this, it is wrong, see the 4 posts below this one !!
 
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Mercedes did not use rolling codes on vehicles prior to at least 2008 Model Year ;)
That would mean they were at least 10 years behind on the security.

I just did a little experiment. I did press the unlock button about 300 times (dedication!) far away from the car. And lo and behold – the remote stopped working. The rolling code got out of sync. I got into the car, press the button twice, turn on the ignition. Hazards flashed once, and the remote works again. Post-facelift, euro-spec, 2002, RF remote.

Reusing a remote from a different car is entirely different thing. That cannot be done this way. But OP's remote most likely just got out of sync.
 

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Yes it is, I have tried everything in the book to be able to use a used key Fob, just maybe an Auto Locksmith could do it by altering the codes in the Fob, which means unsoldering a small chip and reading the hex ................ @Deplore ?????????????
Some MB key making equipment make a distinct file just for the RF, and yes you do unsolder the eeprom to flash the RF file.

W906 (sprinters), 170, 129/140, and 163 were among those. So no reusing eBay key fobs without programming.

MB made rolling codes keys since 98, actually. The very first electronic key fob that rolled out in 98 utilizes two rolling code passwords, one for EIS and one for RF.

W163 also started out with rolling code passwords, except their way was very clumsy and clunky owing to the fact that they had to use a flip blade key and PCF7931/7945 chips. Downside is that those chips are not very good at memory retention and have limited lifespan (200-400k writes vs 1m+ on gen 2 and up keys), plus the uncontrolled environment when you insert the key.... This is why the 170 and 163 have so much trouble with keys, and the problems with the key disappeared when MB switched to electronic key fob in the next generation 171/164.

The sad part is, the 170 also utilizes the PCF7945 immo chips just like the 163.... And the remote PCB will outlast the immo chip. I wouldn't be surprised if owners of a 98 SLK are on their 2nd or 3rd key, but the remote on the first key is still working.
 

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**Premium Member '02 R170 SLK V8 5.0 & '00 SLK320
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MB made rolling codes keys since 98, actually.
OK, apologies to @rfl then, I got that wrong, learn something new every day :(

The reason I said there are no rolling codes is now clearer I think :unsure: .........................

It must be the Drive Auth in ME 2.8 that has no rolling code, because I have 3 different ECU's now, all of which are set up for my V8 Engine, and I can plug any one of them in at any time and it still starts and runs fine ..................

So lets say the Transponder Chip / Drive Auth has no rolling code, but the RF Central Locking / Alarm function in the Fob and the IFZ does ;) Hopefully that will clarify ;)
I'll edit my post to avoid confusion in years to come ;)

Also curiously I have never had one of these Fobs go outta synch, and never tried that particular procedure of re-synching them ;)
I have seen a billion other procedures, but never ........

press the button twice, turn on the ignition. Hazards flashed once, and the remote works again.
I'll try that next time before sending a Customer to a Locksmith :oops:
 

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Discussion Starter · #17 ·
Well….
I took my key to the car, pressed the unlock button twice, put the key in the ignition and turned it. All the lights came on then nothing.
The car didn’t start, no sign of life apart from all the lights on the dashboard.
After trying a few times and trying not to panic I went into the house and got the spare key.
Car started no problem. Spare key unlocks and locks everything. Tried my normal key again and it starts the car, no problem. Still doesn’t unlock the car.
Any idea what I’m doing wrong? Or can’t it be fixed. If not how can I get a spare key that works?
Thanks again to everyone trying to help.
 

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I don't know for sure, but I think perhaps you have a wrong PCB in that Key and therefore it Immobilised the Car until you got the other Key ????????????
 

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Discussion Starter · #19 ·
I don't know for sure, but I think perhaps you have a wrong PCB in that Key and therefore it Immobilised the Car until you got the other Key ????????????
The key that no longer unlocks it is the one I’ve been using since I got the car, it hasn’t immobilised the car and still works, just not for the central locking.
 

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The key that doesn't unlock...there should be an indicating LED under the red cover. Does it blink when you press the button? (The light is really weak, best to try it in the dark.)
 
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