Smart key battery dead

[somv]

Hey guys,

My smart key has run out of battery,

This morning i tried to use the backup key ( the physical key thing)

But the car wont actually start?

can get everything on, But the car wont actually tick the motor over.

Is there something im doing wrong?

[rokpapaziz]

Put a new battery in your original key.

I tried the spare once, but it wouldn't work.

http://clubcj.net/viewtopic.php?t=725&p ... c&start=15

[somv]

Yeah i will be getting a new battery for it, but im refering to the physical key itself, ie putting into the key slot and turnning, car couldnt fire

[SEB15]

The key and remote are working together, once i managed to make the alarm to go off because of that, but i can't really remember how i did.
All you need to do is to replace the battery, the remote has a spot on the edge where you can fit a small philips screw driver! Pop it and the remote should open in half, replace the battery (careful with the terminals are pretty fragile) and should be ok

[megatron]

when you use the metal key, you need to have the back/bottom of the key in the remote still, so remote and metal key are 1 item.

So you take the key out of the remote turn it around and stick it back into the remote, if that makes sense. Then you can use it as a normal key to start the car.

[TheVeeMachine]

Same thing happened to my parents' Citroen.

Apparently the smart keys are coded for the car's immobiliser, whereas the spare 'empty' keys are not - meaning they can do everything but turn on the engine.

I guess they're just included with the car in the event you lock your main key in.

[Sir Lancer-lot]

Got a low battery warning on my dash display so will need to change mine soon too...a handy warning

[The X]

As Alan has said. There is an etched in diagram on the "dead" fob.

Here's how the system works... (get your dork hats on!)
Normally when you have the KOS sitting in your pocket. You turn the start knob, the security system will transmit a radio signal to all devices in the nearest vicinity. All KOS fobs will receive this signal. I've not sniffed the wireless radio signal, but any decent security system, will send out a "challenge request".
The fob will respond with a "challenge response".
Think of it, as when a site requests you for your username/password.
Only YOUR key will ever be able to respond with the correct "answer". Once the car gets the correct answer, it's all systems go.

If the battery is dead, it cannot do this.
So... how do you work around it when you have the responder with no way of sending a response?
Easy! You give it a backup power supply!

How? Magnetic induction, of course!
Hence why the "emergency key" has to be plugged into the KOS fob in the reverse direction to make a crude looking key, with a the KOS attached to the metal key.

When the emergency key is mated with the key barrel , the fob is sitting flush with the steering column.
When you turn the key, a magnetic pulse is fired, which in turn induces a current into the fob, which powers it's circuits for enough time to send it's "challenge response"... and it's all systems go.

If you get really curious, have a look in good light or use a torch and look at the clear plastic surround of the key barrel. You'll see embedded, a coil of copper wire. That's used to induce the current.

Think of it as the same way as those battery-less store theft prevention RFID tags. You walk out the store between two panels (they pulsate magnetic field), the RFID gets a charge to "transmits" a signal to fire off the alarm. Or the more usual way we experience this technology in everyday life. Work access door tags. You swipe your card over the field transmitter, you passive tags charges up and transmits the correct "answer" to unlock the door for you.

when you use the metal key, you need to have the back/bottom of the key in the remote still, so remote and metal key are 1 item. So you take the key out of the remote turn it around and stick it back into the remote, if that makes sense. Then you can use it as a normal key to start the car.

[VRX_08]

I had the same issue a while back, took ages for me to work out how to start the car with the actual key, you would think the key by it self would start the car without needing the remote on the end of it!

I actually had to read the manual to find out how to start the car with the key when the remote is dead! I usually change my remote battery as soon as the car tells me the batter is running low in the remote!