Need Help Batteries Key Phobe

petronic

Junior Member
Messages
151
Just replaced batteries in phob opened the doors fine. Wont start lock stays on. Spare still works how do i set up the key with the new batteries please sat here in my car lol
 

petronic

Junior Member
Messages
151
Sorry meant doors will lock and unlock. The car and lock symbol goes off then on engine turns over wont start.
 

safrane

Member
Messages
16,748
Has the 'grain of rice' size immobiliser chip fallen out when you swapped the battery?
 

CatmanV2

Member
Messages
48,543
Still looking for it if it was this what do i do?

If you can't find it, I'm afraid you're in for another key :(

When I bought one about 5 years back it was IRO £400 £280 for the key and an hour's labour for programming.

C
 

petronic

Junior Member
Messages
151
I think what i am talking about was not it. Is it attached to the circuit board. I thought if the batteries were changed thier was a process to re code it whilst in the car. As i said the doors open and shut engine turns over but the orange lock and car stays on the other key it goes off and the car fires up
 

zagatoes30

Member
Messages
20,759
Certainly sound like the immobiliser chip is missing, did something similar with the first Range Rover we had but quickly realised what was missing and managed to find it on the kitchen floor before the hoover, namely the dog, did his normal thing of eating anything left on the floor.
 

miket

Member
Messages
647
It does sound like you have lost the transponder chip for the immobiliser, it's going to be worth your while doing a forensic search for it, don't know which type of key your 4200 has but it looks like the photo on the single button key, its only small! Best of luck...

Screen Shot 2018-03-22 at 18.42.29.jpg
 

petronic

Junior Member
Messages
151
Ok found it definitely not it. So checked both keys inside they look identical.
So lets assume nothing is missing then what is the sequence for putting the key into the ignition and re setting the code i am sure i read this is a normal reset procedure.
 

petronic

Junior Member
Messages
151
Sorry just saw the picture the bit in the key looks like a piece of broken plastic is that it. No connection or markings to me looks like a broken part of the key. Just sits inside the key. zso if i only have one it is obvious the key wont work what a **** system. Had the car since 2009 never had this problem. Can i get a chip cloned then as i still have one.
 

zagatoes30

Member
Messages
20,759
Yep the bit highlighted is the transponder chip and it won't start without it. So do neither keys have such a piece?
 

CatmanV2

Member
Messages
48,543
Sorry just saw the picture the bit in the key looks like a piece of broken plastic is that it. No connection or markings to me looks like a broken part of the key. Just sits inside the key. zso if i only have one it is obvious the key wont work what a **** system. Had the car since 2009 never had this problem. Can i get a chip cloned then as i still have one.

Not really a **** system, more **** glue. I don't think you can get the chip cloned, but it might be worth asking someone like Timpsons

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CatmanV2

Member
Messages
48,543
Ok found it definitely not it. So checked both keys inside they look identical.
So lets assume nothing is missing then what is the sequence for putting the key into the ignition and re setting the code i am sure i read this is a normal reset procedure.

Oh and there is no sequence. What I suspect you're thinking of is the process to get a key to arm / disarm the alarm, and open the doors. The central locking / alarm and immobiliser are completely separate systems. The alarm uses a rolling code radio transmitter (which needs batteries) in the key. The immobiliser uses a passive radio frequency ID transponder which doesn't need batteries, but is also in the key.

When you press the button on the key it sends a coded signal which the alarm ecu receives, decodes, validates and then locks / unlocks whatever.

When you go to start the car among the check the ECU makes before it goes PTS (permission to start) is to send a signal to an antenna around the ignition lock barrel. That in turn causes a potential to be generated in the antenna of the RFID chip in the key. The RFID chip so triggered then sends a signal back to the antennal in the car, which is then validated (or not) by the CODE system. Wrong RFID chip = wrong signal = no PTS. No RFID chip = no signal = no PTS :(

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petronic

Junior Member
Messages
151
Sounds like a micro chip in a pet. So if that is the case inside one key is a label with figures and numbers does this identify the chip
 

CatmanV2

Member
Messages
48,543
Sounds like a micro chip in a pet. So if that is the case inside one key is a label with figures and numbers does this identify the chip

It does, it is. I think someone tracked them down a few years back, but you need to buy about 10,000 of them from the only supplier they can find. Then you still need to get it coded to the car.

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