Key fob battery change

[hodroyd]

Now you have me thinking, is it IR, or radio transmit, to be honest I'm not sure now, it could be radio. The rolling code I'm not sure if that is done by radio, as radio is not that secure and can be copied as a frequency..??

 

[2b1ask1]

No IR on these keys just radio also imobilser is a proximity induction chip (like a shop security tag) they are also flash programmed by dealers and independents.

 

[CatmanV2]

Sure mine isn't IR as I often blip if from my pocket, and I've not had any holes yet

Newton, that is precisely my understanding, so I cant see any way that removal of the induction chip will stop you from remote locking / unlocking the doors, but I stand to be corrected.

Of course, we know the car won't start without that silly bit of black plastic

C

 

[2b1ask1]

That's right C the two are not connected.

 

[CatmanV2]

Glad we got to the bottom of that Tony, you're doing something odd

Thing that I'm thiking may be an issue is if the RFID cannot be 'seen' within a metal housing. There are bypass kits available, for use with PKE and remote start systems, but I'm not convinced that it's a great idea yet.

C

 

[tonym3]

OK so the little black plastic bit is needed, whatever it is!! I think you are right about it not being IR as it works inside a pocket etc..

What I meant by it working/not working was with the key open, if you take the electronic parts out including the battery and the switches etc.. Keep them all together as they would be inside the key then press the open button, it will not work unless it is next to the little black plastic thingy. Trying to figure out what the black plastic thingy is and if it can be replicated without having to re-code etc..

I guess an alternative would be to try and make a case to go over the existing one, however not site how successful this would be, perhaps it will mean sacrificing the old case to remove the magical black plastic square.

 

[CatmanV2]

That plastic thing is an RFID tag. it's a passive transponder. What you're suggesting makes very little sense, I shall have a look when I get a chance

C

 

[hodroyd]

I seem to remember an earlier thread, which actually put the black plastic square on the circuit board, I think they are stuck on, or should be. If it has become detached and stuck itself to the case, this may be incorrect..??

 

[2b1ask1]

Once opened remove the PCB so just the transponder remains in the half shell, flip it over and tap it out on a hard surface. There is just a tiny smear of mastic fixing it in place, DON'T be tempted to lever it out as they are easily broken as they are made of something akin to bakerlite!!!

 

[tonym3]

OK well if that works it should be all doable, I wanted to be able to keep the old key to revert back if required.

I will have a play later to see how easy it comes out just a case of finding a way of mounting the chip in the new key, I'm assuming it will work in a metal case? I've had fiat remote keys before which are in metal.

 

[CatmanV2]

Depends. If the metal is too think, the radio interrogation may not get a response from the transponder. Sure it can be worked around though.

C

 

[tonym3]

Ok quick experiment got the transponder out, then wraped it all in a layer of foil.
Unsurprisingly it doesn't like operating through the foil, even with some holes in the front it wouldn't open the doors.

Any idea on getting it working inside a metal case?

 

[CatmanV2]

There's something odd here, Tony. It shouldn't have *anything* to do with the doors. It should only be for the CODE. Unless we've discovered something else here. Newton, what's your take? Might the car be using the active ping from the key to query the passive RF for door opening?

C

 

[2b1ask1]

I've never heard of this, as far as I'm aware it should be two entirely separate systems, leave the imobilizer chip out of the key, rebuild it and see if it unlocks/ locks ok? It won't start that's for sure...

 

[Chrisbassett]

Ok, a little experiment later and...

Removed the electronics from the shell of the key and out of any kind of range of an RFID. The button was still able to lock / unlock / set the alarm. Therefore the radio for the remote lock/unlock does not need the little black chip to be there for it to work

Removed the black chip from the key and was able to open the doors, put the ignition on, but not start the car. Therefore the ignition lock must have some RFID-type device that gets a code from the little black chip and unlocks the immobiliser.

So, any new key shell will need to
1. Allow a radio signal out from key's transmitter to let the remote lock/unlock work
2. Contain the little black chip and allow a radio signal in/out so the ignition system can interrogate it and receive a code.

The RFID signal is likely to be very weak and therefore probably needs a plastic part to the body of the key to be able to work unless the black chip is presented on the outside, but as it's pretty fragile I doubt this would be a good solution.

For those who it means anything to, think iPad / old style iPod where there is a black plastic part of the case so wifi can work.

So we might be talking about a plastic shell with metal top & bottom facings or a metal shell with plastic parts at the front (key end) to allow the signals out.

 

[CatmanV2]

The antenna for the CODE system is around the ignition lock barrel, according to the workshop manual, anyway.

C

 

[hodroyd]

Now we seem to be getting somewhere close..!!

 

[Chrisbassett]

Is carbon fibre transparent to RF?

 

[hodroyd]

I would doubt it being carbon based, but you never know, I think this one is trial and error until the right combination is found..??

 

[tonym3]

My thinkings today went from having some plastic put into the key, as described above like a iPad etc..
But I thought this could be difficult to produce without looking cheap or becoming too costly, then I though about having small holes around the black plastic chip. Drilled into the metal, however could condensation then become an issue?

I'm thinking looks would be better with drilled holes, but if apple went the route of plastic is this better way, the old ford keys used to have a plastic insert at the top for the immobiliser, could look at incorporating something like this to attach the black box to.