Key frequency

STEW · 01-11-2005, 07:59

odd one...unlocked my boot last night with the middle button on the remote and unlocked my next door neighbour's new Citroen Picasso. He ain't amused. His remote doesn't unlock the fabia..... Is this a case of identical frequencies? Anyone else noticed anything similar?

JRHartley · 01-11-2005, 08:03

Two words STEW .... 'French electrics'

**mannyo** · 01-11-2005, 08:15

All the keys are on the same frequency for most makers. The key to unlocking is having the ecu understand the special code that the key sends when you press unlock. Dont know why the citroen would understand your code (which is different each time you press the unlock button). Perhaps it was a one off.

ScoobyChris · 01-11-2005, 09:28

Quote:

Originally Posted by mannyo

Dont know why the citroen would understand your code (which is different each time you press the unlock button). Perhaps it was a one off.

Yep it should be a rolling code so it's unlikely it'll work again.... if it does, he might want to pop into his dealer

Had some fun with a friend who fitted remote locking to his Corsa van. Every time he unlocked his van when it was parked near my Scooby, I would unlock the Scooby. Then when he relocked his van, the Scooby relocked too. He thought it was great and showed his mates but bizarrely, the Scooby mysteriously locked itself every time he walked near it too

Chris

andy ellis · 01-11-2005, 11:24

One of my 4 keys (2 fabia's) will unlock and lock both cars but only 1 of the 4...... Work that one out!!!

maffwilson · 01-11-2005, 13:28

Quote:

Originally Posted by andy ellis

One of my 4 keys (2 fabia's) will unlock and lock both cars but only 1 of the 4...... Work that one out!!!

This is presumably because a range of codes is broadcast and accepted because each one of the four keys are asynchronous to the car and of course to each other. They output a different 'range' of codes because you press the button a different amount of times on each fob, and sometimes not in 'earshot' of the receiver (car).

One of your keys, however, happens to be outputing a correct range of codes acceptible for both cars, the others not because they are at a different stage of the rolling codes. It's an unlikely co-incidence, but perfectly possible (as is the Citroen case).

I assume if you press the button lots and lots (and lots!) of times out of range of the vehicle, or similarly never use the spare keyfob to unlock it, at some point the fob will stop working because the broadcast codes will be too distant from the accepted ones on the vehicle. Can't be bothered to experiment though.... (oh great, I've managed to lock myself out my car!

)

andy ellis · 01-11-2005, 20:32

Had the both cars for 3 years now and they have done it since day 1! One on a 51 plate and the other on a 52 plate...... is the magic key pocessed?

fordfan · 01-11-2005, 20:39

One of the field engineers who works for an importer was telling me in his previous job with Chrysler how he had a day trip to France with all his car breaking in tools. It turned out that the Coastal radar signal had locked a train load of Chrysler Voyagers which all had their keys inside.

STEW · 02-11-2005, 08:00

Interestingly me and my neighbour with the Citroen have tried again and can't make the citroen open with my key again (or vice versa) although it did it twice at the time. His dealer thinks his car reset it's coding after he restarted and will be ok now ???? Must have been a one off coincidence but makes you wonder how secure remote locking is.

maffwilson · 02-11-2005, 11:59

Quote:

Originally Posted by STEW

Interestingly me and my neighbour with the Citroen have tried again and can't make the citroen open with my key again (or vice versa) although it did it twice at the time. His dealer thinks his car reset it's coding after he restarted and will be ok now ???? Must have been a one off coincidence but makes you wonder how secure remote locking is.

The odds are a one in 1.074 billion chance that a system based on 40 bit system code would respond to a random security code & be recognized as valid (this is quoted by Texas for one of their remote access chipsets).

So yes unlikely, but possible as you've seen. Sometimes you do win the lottery...

The 'random factor' applied to the system - you've pressed your fob a different amount of times to your neighbour, plus the 'random' number generator built into the system to hop the codes - means that now your keyfob transmitter is not in 'sync' with the Citroen's decoder, what the dealer refers to as 'reset'.

01-11-2005, 07:59	#1
STEW Briskodian Join Date: Nov 2004 Posts: 82 Thanks: 0 Thanked 0 Times in 0 Posts	Key frequency odd one...unlocked my boot last night with the middle button on the remote and unlocked my next door neighbour's new Citroen Picasso. He ain't amused. His remote doesn't unlock the fabia..... Is this a case of identical frequencies? Anyone else noticed anything similar?

01-11-2005, 08:03	#2
JRHartley Briskodian Join Date: Nov 2004 Location: North west Posts: 2,009 Thanks: 0 Thanked 16 Times in 13 Posts	Two words STEW .... 'French electrics' __________________ I'm a celebrity...... Get me out of here !!!

01-11-2005, 08:15	#3
mannyo BRISKODA Staff Join Date: Nov 2002 Location: Stevenage Herts. Posts: 11,112 Thanks: 36 Thanked 304 Times in 284 Posts	All the keys are on the same frequency for most makers. The key to unlocking is having the ecu understand the special code that the key sends when you press unlock. Dont know why the citroen would understand your code (which is different each time you press the unlock button). Perhaps it was a one off. __________________ Manny 2005 Octavia 2.0TDi Elegance combi my skoda website http://www.octaviars.co.uk Join the briskoda.net folding team click Here for more info

01-11-2005, 11:24	#5
andy ellis Briskodian Join Date: Nov 2003 Location: Warrington Posts: 1,289 Thanks: 0 Thanked 1 Time in 1 Post	One of my 4 keys (2 fabia's) will unlock and lock both cars but only 1 of the 4...... Work that one out!!! __________________ Fabia TDI PD100 "Q" and driving school car. Citroen C4 Coupe 1.6hDi+EGS with disability adaptations.

01-11-2005, 20:32	#7
andy ellis Briskodian Join Date: Nov 2003 Location: Warrington Posts: 1,289 Thanks: 0 Thanked 1 Time in 1 Post	Had the both cars for 3 years now and they have done it since day 1! One on a 51 plate and the other on a 52 plate...... is the magic key pocessed? __________________ Fabia TDI PD100 "Q" and driving school car. Citroen C4 Coupe 1.6hDi+EGS with disability adaptations.

01-11-2005, 20:39	#8
fordfan ECUless Join Date: Mar 2005 Posts: 1,957 Thanks: 30 Thanked 225 Times in 196 Posts	One of the field engineers who works for an importer was telling me in his previous job with Chrysler how he had a day trip to France with all his car breaking in tools. It turned out that the Coastal radar signal had locked a train load of Chrysler Voyagers which all had their keys inside.

02-11-2005, 08:00	#9
STEW Briskodian Join Date: Nov 2004 Posts: 82 Thanks: 0 Thanked 0 Times in 0 Posts	Interestingly me and my neighbour with the Citroen have tried again and can't make the citroen open with my key again (or vice versa) although it did it twice at the time. His dealer thinks his car reset it's coding after he restarted and will be ok now ???? Must have been a one off coincidence but makes you wonder how secure remote locking is.

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