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Discussion Starter #1
I have made some posts on yhis before but can't find them.

I havew been having trouble trying to activate a second key for my 307. I have spoken to an independant Peugeot mechanic who has PP. he says he has never got a second hand fob to work, only virgin ones from the dealers.

This got me thinking, the chips on the fob PCB are ROM (read only memory) just like in a PC BIOS. These can be flashed to upgrade so why can't the key fob.

There has to be a way to re-flash them or wipe them of the previous car info, trouble is how.

Has anyone ever got a second hand key fob to work, this is one thing i have noit found on here.
 

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Well, I was trying this recently with a key on a Berlingo van. I was reliably informed that you cannot programme keys form the scrapyard. And I certainly couldn't get Lexia to do it.
The only thing I did find out was that you can maybe wipe the EPROM on the chip with ultra-violet light!:)
Phil
 

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hawkeye said:
No that a new one on me wiping with an ultra-violet light!
From Wikipedia:
An EPROM, or erasable programmable read only memory, is a type of memory chip that retains its data when its power supply is switched off. In other words, it is non-volatile. It is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages than those normally used in digital circuits. Once programmed, an EPROM can be erased by exposing it to strong ultraviolet light from a mercury-vapor light source. EPROMs are easily recognizable by the transparent fused quartz window in the top of the package, through which the silicon chip is visible, and which permits exposure to UV light during erasing.
Mercury vapour lamps are very rare and horribly unhealthy - I remember working with one for about 5 minutes and came away feeling as if I'd eaten 3 pounds of cream cakes and then gone on a big-dipper. (Perhaps I should have used the goggles after all...)
 

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Discussion Starter #5
EPROM's can be written to, it's called flashing. You can update you PC bios chip which is an EPROM.

If Planet can write to this EPROM in the first instance why not a second time.
I was thinking of s strong magnetic field may do it. We have some rare earth magners at work, they are incredibly powerful if you had your finger between them as they were pulled together they would cut the finger off they are that strong.

I'm just picking things out to try now, i don't have access to a UV lamp though.

I have noticed a lot of talk about keys on this site in other posts but never one that says they have successfully reprogrammed a key...........
 

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from my knowledge from where i work and courses etc....ROMs can be overwritten to rewrite or to upgrade...not just pcs do this...tv's, mobiles, virgin media boxs, sky boxes...infact anything with a main board(motherboard) has ROM.

now it wont be the key chip that will be blocking but rather, a software incompatabilty within planet or lexia...not allowing you to do this.

also if you wish to wipe the memory off using very stong light...or magnets...you could just as simply use a strong fridge magnet...the componants inside the eeprom chip are very small and so is the charge it holds (memory) all you need is a good fridge magnet to distort this charge and voila, you either have wiped memory or a corrupted memory...

i hope that makes sense and is of some use.
 

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Yeah, I thought strong magnets would do it. I have some from out of an old hard drive (surprising HOW strong they are) but they didn't seem to do a thing with my second hand Berlingo key! :(
Phil:thumb:
 

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Discussion Starter #9
Removing the battery will no affect an Eprom.

I will try the magnets tomorrow, i cant make it worse than it is..........i hope.
 

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i meant take the battery out, as that could be keeping the current (memory) intact. by removing the battery then trying a strong magnet it may disrupt the current (memory) and either wipe/corrupt it, as there is nothing to keep it intact
 

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I know it's a bit late......But

My previous car was a Peugeot 806, when I bought it it only had 1 key and it wasn't even the posh folding one. I bought a secondhand folding key from ebay, apparently the seller had sold the car and forgot to give the spare key to the new owner. I paid a guy who lives locally £40 and he programmed the key in a few minutes and cut me a new blade (he's mobile as well), worked a treat.

Oh, and the key I bought was from a Citroen NOT a Peugeot!

So it can be done.

Hope this helps
 

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Yeah, but IS there a difference between key fobs, with battery and button, and just plain key with a transponder chip in it????
Phil
 

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I've looked into this so I'll give my 2p...

There are 2 parts to these keys that you have to sort out in different ways to get them to work.

1) The transponder in the key (This is included whether the key has buttons on it or not). If you open up the body of the key, the transponder is a small rectangular blob on it's own, sunk into the main shell of the key next to where the key blade slots in. (For the standard 2 button key). It is not a part of the circuit board within the key. This works by induction...so when your key gets close to the ignition in your car, the car send out a radio signal which energises the circuit in the transponder, which returns a code. If your car recognises the code, it allows ignition etc..
The transponder is not an eprom/rom, it simply returns a code that (AFAIK) can only be changed with specialist equipment (and only if it is a writeable transponder), but there wouldn't be any benefit in trying to change the code anyway.
To get this part of the key working, you should be able to use planet to add the key in to the list of acceptable keys. I've heard of this being done before, but haven't done this myself so unfortunately can't help.
To clarify though, the transponder holds no information about a particular car, it just returns a code. The car has to be changed to accept that key code.
Potential problems with this are if the car is somehow programmed to only accept certain code ranges, or if there are different frequencies in use for activating the transponder. I'm just guessing at this though.

2)The other problem is getting the buttons on the blip to work. This is what the circuit board inside the key is for. The blip is more of an active system in that it actively transmits a code when you press the button that your car will read and decide if it wants to open up. The key transmits an encrypted code. Every time you press the button the code changes. Your car knows the algorithm that the key uses, so will know what the next 60-100 or so codes will be. (this is why it still works if you press the button out of range. If you keep pressing the button, eventually the blip will stop functioning and have to be re-synchronised with the car). I'm not entirely sure how the setup of the key blip with the car works. There are several explanations on the web about how to get a new blip working with your car, but I have tried these and not had any success.
I have a feeling that the ecu in the car stores transponder and blip codes as a pair. So if you haven't got the transponder working with the car, you won't be able to register a new blip.

Thats really all I know about these keys and blippers. If I ever get hold of a planet cable I'll have a proper go at getting my keys to work and post the results up.

Hope this info is of some use...
 

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paddy69 said:
Yeah, but IS there a difference between key fobs, with battery and button, and just plain key with a transponder chip in it????
Phil
Not as far as transponder operation goes.
 
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