C5 Program Spare Key With Lexia

acrowot · Unread post by **acrowot** » 16 Sep 2010, 21:15

I have a C5 with only 1 key, I also have a Lexia3 and I have a spare key and fob from a scrappy. I can get a key blade cut and I can insert it into this spare keyfob, I also have a card that shows a key on it with 2 arrows pointing to an area of the card that is covered with some sort of plastic material with security written on it, is the keycode likely to be under this plastic or is some sort of electronic reader required to read this code. If this is the keycode and I can retrieve it would it be possible to recode this scrappy key to use as a spare.

Unread post by **Paul-R** » 16 Sep 2010, 23:50

This was exactly my idea but it didn't work. Someone told me there were three different fobs (or at least the plastic bit the blade goes into) for C5s. I didn't believe him but now I'm not so sure.

I made the mistake of glueing the blade into the new fob before trying to pair the damn thing so, even though I have another fob to try, I haven't "persuaded" the blade out yet!

I might yet get the thing working.

acrowot · Unread post by **acrowot** » 17 Sep 2010, 00:01

Paul-R wrote:This was exactly my idea but it didn't work. Someone told me there were three different fobs (or at least the plastic bit the blade goes into) for C5s. I didn't believe him but now I'm not so sure.

I made the mistake of glueing the blade into the new fob before trying to pair the damn thing so, even though I have another fob to try, I haven't "persuaded" the blade out yet!

I might yet get the thing working.

Paul, I am not sure what you mean here, I thought you would have to glue in the new blade before you could pair them, the Main Dealer tells me they would need all keys and the key card to pair them. Is your card the same as the one I have in my OP?
John

Unread post by **RichardW** » 17 Sep 2010, 07:55

The 'security' bit of the card is just a rub off strip - do so and it should reveal a 4 digit code that will allow access to the key setting part of the Lexia menu. Of course if you just get a key blade cut and re-program the plip, it will open the car, but not start it, as you also need to include the immobiliser chip which is included in the key blade somewhere.... Presumably (although not sure) these can also be coded in with the Lexia.

acrowot · Unread post by **acrowot** » 17 Sep 2010, 10:23

RichardW wrote:The 'security' bit of the card is just a rub off strip - do so and it should reveal a 4 digit code that will allow access to the key setting part of the Lexia menu. Of course if you just get a key blade cut and re-program the plip, it will open the car, but not start it, as you also need to include the immobiliser chip which is included in the key blade somewhere.... Presumably (although not sure) these can also be coded in with the Lexia.

Thanks for your reply Richard, I have obtained a spare Keyfob from a scrappy and I intend to have a key cut and insert it into this Keyfob and then with Lexia program the chip in this Keyfob to start my car.
John

Unread post by **Paul-R** » 17 Sep 2010, 11:08

acrowot wrote:Paul, I am not sure what you mean here, I thought you would have to glue in the new blade before you could pair them

Yes you have to have the blade in the fob so that it's close to the column lock - I'm just saying that I shouldn't have glued it in until it had paired. Glueing made it damn difficult to get the blade out and try in another fob.

There's a post on here sonmewhere detailing how I did this as I also did the keys of the Xsara at the same time (I managed to unpair one of them!).

acrowot wrote:the Main Dealer tells me they would need all keys and the key card to pair them.

That's true. You have put in how many keys are being paired so all have to be at hand for the process. Previous pairings are wiped.

acrowot wrote:Is your card the same as the one I have in my OP?
John

My C5 didn't have a card - I had to pay £20 to get the details. I have a card with the Xsara and it sounds the same.

acrowot · Unread post by **acrowot** » 17 Sep 2010, 11:20

Thanks for the clarification Paul, what worries me is that if the original key is wiped in the re-prog. process I could finish up with no programmed keys and be unable to start my car.

Unread post by **Paul-R** » 17 Sep 2010, 11:24

There's no option to put zero keys but it's always a possibility that the original key (or reading coil on the column lock key barrel)might choose that very moment to throw a wobbler and refuse to pair.

It all depends on how much you believe that the sky is about to fall in on your head!

acrowot · Unread post by **acrowot** » 17 Sep 2010, 11:32

I have just had a word with a local locksmith and he says it is not possible to re-prog a key that has already been programmed for another car, the fob has to be a virgin.

MikeT · Unread post by **MikeT** » 17 Sep 2010, 12:10

acrowot wrote:I have just had a word with a local locksmith and he says it is not possible to re-prog a key that has already been programmed for another car, the fob has to be a virgin.

He's half right and half wrong. The key chip is pre-programmed and stays that way for life. It's the car's ECU that's then programmed to accept the key's code.

acrowot · Unread post by **acrowot** » 17 Sep 2010, 12:44

[quote="MikeT"][quote=He's half right and half wrong. The key chip is pre-programmed and stays that way for life. It's the car's ECU that's then programmed to accept the key's code.[/quote]

Does this mean then that this scrappy keyfob will be no use to me or can the ECU hold more than 1 key code.

Unread post by **Paul-R** » 17 Sep 2010, 16:01

I can't remember the exact number but I think it's something like 5 keys that the ECU can hold details of.

MikeT · Unread post by **MikeT** » 17 Sep 2010, 16:57

acrowot wrote:
MikeT wrote:
He's half right and half wrong. The key chip is pre-programmed and stays that way for life. It's the car's ECU that's then programmed to accept the key's code.[/quote wrote:
Does this mean then that this scrappy keyfob will be no use to me or can the ECU hold more than 1 key code.
No, the ECU (which can hold at least three key codes that I know of) is first wiped of all programmed keys when you program new ones. You could program my key to start your car (if the key fitted the ignition) as I could program yours to start mine.

acrowot · Unread post by **acrowot** » 17 Sep 2010, 17:30

Thanks to all who have answered, it seems then that the Keycode on the credit card is needed to allow the ECU to accept and pair with the codes that already exist in the Keyfobs. Paul what is the problem that you have, it seems that you have tried to do what I am trying to do but without success.

Unread post by **Paul-R** » 17 Sep 2010, 18:37

MikeT wrote:You could program my key to start your car (if the key fitted the ignition) as I could program yours to start mine.

As you say, by changing the blade over.