C4 Replacement Fob Not Working

[GiveMeABreak]

If you mean the key without the fob - then the transponder chip is hidden inside the plastic of the key holder. And it can only be used to physically unlock the door and start the car. But most newer cars have 2 fobs types now.

[Cutac]

I've found out, PSK for my car.
I don't think we understand eachother.
First of all, can my new key be 0536 if my key is 0523 and vice versa?
And, why does one PCB have some black chip and one doesn't? Like in http://c4owners.org/plugins/forum/forum ... php?202851.

[GiveMeABreak]

1) From what I can tell, the 0536 fob contains the battery on the key shell and the 0523 has the battery on the PCB. - These are different types.
2) The transponder coil can be like any of these three:

3) That is separate from the electronic chip:

The above picture shows 4 different fobs and the bottom shows them on the other side. You can see the transponder coils like in the previous pictures, but on these you can see the electronic integrated circuits that do the locking / unlocking transmission sending and the other functions I was telling you about for the third button like the boot, lights and windows - or for holding the locking button to close windows etc. The integrated circuits are different for the models and functions. Do you understand now?

[Cutac]

Okay, I get all that, but...
As you can see, fobs on the picture seem to have different layouts. 0523 has more microchips on the button side and just immobilizer transponder on the battery side, while 0536 has less microchips on the button side, but has some microchips on the battery side. Let's say those are exact same components but in different layout.
And that's where that photo of my key from the previous page comes into the story. It is 0523, so more microchips on the button side, but on the battery side, apart from transponder(unlike 0523's in the group photo), it has an additional chip that none of these 4 keys have. My 2 button key from the B7 also hasn't got that extra microchip, so I'm curious if that chip is needed for window operation.

[xantia_v6]

The chip you circled above appears to have only 2 connections, so probably not very sophisticated. Given it's size, I would guess that it is a capacitor to help the battery feed current spikes when the remote is operated, prolonging battery life.

[Hell Razor5543]

The chip you circled above appears to have only 2 connections, so probably not very sophisticated. Given it's size, I would guess that it is a capacitor to help the battery feed current spikes when the remote is operated, prolonging battery life.

It could be the timing crystal.

[Cutac]

It says "13.560 D:61" on it, seems like it is a crystal.
Doesn't seem too important, could lack of it cause any mishaps in fob usage?

[Cutac]

Colleague who knows a thing or two about Citroens saw my Chinese key disassembled and said that it's just plain low quality rubbish and that is why it doesn't work.
Bought from SIKALI, if anyone's wondering.

[xantia_v6]

I would agree (particularly with the markings) that it is a crystal, to provide the frequency reference.

In photos 1 and 4 above, the crystal is the silvery component near the bottom on the button side of the PCB, on 2 and 3 it is the black component to the right of the processor chip on the battery side.

I believe that some genuine PSA fobs have the immobiliser function built into the same processor chip as the locking function (the copper coloured immobiliser coils), but after-market fobs (and other PSA fobs) generally have the immobiliser function separated (the black immobiliser coil/chips)

[Cutac]

Thanks for the info!
I'll update this topic when I find either a working key or my key that's been lost

[Cutac]

So...
Can I buy an ASK key if it says FSK on an original key card?

[GiveMeABreak]

I would say NO - because they are based on different types of modulation. You need the correct one for your car.

[Cutac]

Hmm, Chinese aren't offering any FSK keys...

[Hell Razor5543]

I knew somebody who had a fault with his keyfob. When he checked he found the crystal was not working. After he fitted a replacement the fob worked.

[xantia_v6]

I am surprised that there ever were ASK keys from PSA, maybe the chinese suppliers actually supply FSK keys without knowing it. Does not hel with the confusion.