C4 '06 - Programming new remotes & keys

[admiral51]

These are the pics from my 2005 C4 remote/keyfob if it helps

[xantia_v6]

The thing that looks like a coil with a white label is, I think, the immobiliser transponder chip with a coil wound around the outside of it. It seems to be soldered to the pcb, so would not be easy to move from one pcb to another.

[Paul-R]

I'm not at all sure that there is a chip in there. According to this data sheet it's just a coil which, with an associated 681pF capacitor, resonates at 125KHz.

https://www.mouser.com/ds/2/597/4513tc-933711.pdf

I've had an even closer look at my X7 PCB. I can't see any connection between the coil and anything else**. The solder pads near to the coil don't connect anywhere. Maybe the capacitance is provided by the printed circuit itself. I must confess to being quite confused over this. I'm still not yet convinced the 125KHz signal is for the immobiliser. I think it's for the remote locking. I am willing to be convinced otherwise if anything concrete can be found!

**EDIT, found them. They're underneath the coil itself. There are two through holes to the other side just underneath the edge of the black chip.

[Hell Razor5543]

Take a look at the lower picture, board on the left (ninth post). There is a component with a label on it. You need to zoom in to see the label is on a component, and not just stuck to the board. This component does not appear on the board to the right. Now, if you compare the two fob casings you will see that the one to the left is designed to accommodate a chip-on-board design, while the casing to the right can accept a separate loose chip.

[Paul-R]

Ah yes, I see the difference. The label is stuck on the coil which I posted the data sheet about. And I can see the recess for a discrete item on the other fob. That does lend evidence to the coil being involved with the immobiliser rather than the remote locking as both boards have microswitches.

But that doesn't help with identifying the part of the circuit for the immobiliser for the board with the coil.

[teuski]

As far as I can see you will need the original transponder chip from the original keys to be able start the car. The BSI can store up to 5 keys and their IDs. I doubt you can use another transponder chip from another car’s key.

I'm sure a blank chip with confidential code can be programmed to my car. Why else the dealership can provide new keys if the originals are lost?
On the other hand, is there such thing as a "blank" chip? I doubt the pairing process does anything to the chip itself (write data to the chip, i mean), it just pairs the individual chip in question with the car.

Yes, the bit with the label is the coil and probably the chip is inside it. And yes, the traditional chip embedded in black plastic also must have a coil inside it.
Having the solder pads not connected to anywhere on the PCB makes sense. Why should the chip connected anywhere because the traditional one doesn't have to?
My best guess is, that with the confidential code i should be able to program any suitable chips to the car, be they black ones or bare coil ones.
I remember reading somewhere that the confidential code could be obtained from Citroen Service with right credentials instead of going to a delership desk. Could anyone confirm this?

But at least i have one working chip but zero working remotes, so that's my first priority

[GiveMeABreak]

I'm sure a blank chip with confidential code can be programmed to my car.

I didn't say it couldn't - I was referring to using parts from another car fob in the context you mentioned earlier. A new or virgin fob from the dealer can be programmed to a vehicle once, but re-paired again as needed (you may want a third or fourth fob at a later date), in which case the whole 3 or 4 fobs must be paired again in the same programming session - up to the maximum 5 keys allowed by the BSI in this case.

My best guess is, that with the confidential code i should be able to program any suitable chips to the car, be they black ones or bare coil ones.
I remember reading somewhere that the confidential code could be obtained from Citroen Service with right credentials instead of going to a delership desk. Could anyone confirm this?

A dealer will be able to supply the confidential code - on production of appropriate documents and for a nominal fee (free to about £25 in my experience in the UK, depending on your dealer). I would be wary about using anyone other than a main dealer for obtaining a code - after all it is supposed to be confidential.

[Paul-R]

Is there a set procedure laid out for initialising and pairing a new key for the 06 C4 Marc? And the X7 come to that?

[RichardW]

I've done it on the C4 Picasso...

Go into the BSI, and repair, then 'Pack Reparation' IIRC.
Enter the confidential code, and no of keys to code (including existing ones!)
Then just follow the on screen intructions, which is just put the key in, turn on, wait a few seconds, turn off. Then pair the remote.

AFAIK the car writes something to the chip in the process, as it is not possible to code a 2nd hand key to another car - no idea how it does it though!

[GiveMeABreak]

Is there a set procedure laid out for initialising and pairing a new key for the 06 C4 Marc? And the X7 come to that?

There are 2 parts Programming and Synchronisation - but the actual programming procedures are contained within Diagbox / Lexia at the point of starting the process - but the confidential Customer Code is needed of course.

There were several changes to the immobiliser systems - the earlier vehicles had a more basic type of system (think keypad immobiliser from the XM days) to basic transponder types. The second generation types (as used on the X7) are the ADC2 anti starting system and the ADC2R anti starting system - reinforced. These types use an exchange programming and verification of encrypted codes. The latter system (where fitted) also utilises the exchange between the BSI and the Dynamic Stability Control (ESP ECU).

Just for interest, looking at a possible fault code of FC81, you will see the causes and possible solution - note the "writing to memory" part...

Fault code	FC81
After sales description of the fault code	Fault in the transponder incorporated in the ignition key: Not characterised
Description of the diagnostics	Impossible to write in the memory of the key transponder during the initialisation of the keys
Conditions of activation of the diagnostics	In the key initialisation phase
Conditions of disappearance of the fault	Writing possible in the memory of the key transponder during the initialisation of keys
Down-grade modes if fault present	-
Switching on of the warning lamp and/or warning message	Possible display of the message "electronic immobiliser faulty"
Main customer complaints likely	Starting impossible
Suspect areas	keys (Transponder part)

[teuski]

I changed the batteries and tried to sync both remotes, no success. I even put the working chip in the chinese remote and used it to turn the ignition on while trying to sync it.

I could somehow understand that the remote that was configured to the other car won't work but the chinese one should be virgin...

[GiveMeABreak]

If you are using a 'virgin' blank chip, you can't synchronise it until the key has been actually programmed using Lexia / Diagbox, then it can be synchronised.

Synchronisation (putting the key in the ignition, switching ingnition on and holding the lock button for a few seconds) will only re-synchronise when the fob has been operated from a long distance too many times for example and won't make any difference if the key has not yet been programmed and accepted by the BSI.

[Hell Razor5543]

I am going to use an analogy to explain things here, if you don't mind. Imagine you have started working for a company with a high level of security. When you are inducted into the company you are given a security card that allows you access into the company building (this is the BSi and the immobiliser chip). Then, when you log into your computer for the first time, you are asked to change your password away from the generic starting password (this is pairing the remote to the car). Occasionally you will have to change the password (this is changing the battery in the fob, and then pairing the remote to the car again). Unless you can get into the building you cannot log into the computer. This is why you cannot pair a remote to the car until the car 'knows' the immobiliser chip.

[teuski]

Ok so the immo chip and the remote work together in some way? I was thinking they are two separate things, as Lexia states the remote syncing procedure could also be done by itself.

So now i have two options, either get just the code from a citroen shop and try if i can pair a used remote with a chip to my car using my Lexia and take a risk it doesn't work out OR get a whole new remote key and sync from the shop?

Is it the same thing with older oval C5 keys? I have a '03 C5 with just one key and a bunch of old remotes from other cars. Could i reuse them if i have the code and just need to get an another key blade?

[Hell Razor5543]

As far as I know the immobiliser chip and the remote only need to work together when the remote is being 'paired' to the car (as, during this stage, the car needs to 'know' the key is authorised to control the central locking). This is part of the reason the key needs to be turned to a position in the ignition switch (as this will trigger the 'handshaking' stage of the authorisation test).