C5 2002 Central Locking

[Guest gaztank]

hi every body, i just had the same fault come back from xmas time. f18 fuse blown, this fuse protects the autobox select switch, fly wheel angle sensor and the diagnostic plug. my wife was using the car as normal, she stopped the car briefly went to start it again, dash lights on but no starter, she replaced the fuse and it worked again. the only other fault she had that day was she parked the car at the norwich airport park and ride and locked the doors with the fob remote, checked the door handles to see if it had locked. all ok. and on return a few hours later the car was unlocked. is the central locking related to the f18 fuse and is there a frequency used at airports which can unlock car doors, this is the second time this has happened. do you guys have any clues so i can nip this in the bud. thank you. gaz.

[jacktar51]

Gaz....The remote key fob is VERY sensitive on the lock/unlock buttons,on some remote fobs,you can accidentally unlock the doors after correctly locking them,just by dropping the key fob into your pocket(or in the wifes case)handbag..I have two key fobs one is much more sensitive,( hair trigger ) than the other,perhaps she has a very sensitive one, that operates at the slightest touch,I have taken to checking my car is locked,then keep the remote hanging on its keyring from my finger,until I am far enough away to be sure I dont accidentally unlock it,before dropping it into my pocket....My other key fob has been no trouble...so perhaps your remote locking isnt faulty at all(With a bit of luck).....Jack.

[gaztank]

Gaz....The remote key fob is VERY sensitive on the lock/unlock buttons,on some remote fobs,you can accidentally unlock the doors after correctly locking them,just by dropping the key fob into your pocket(or in the wifes case)handbag..I have two key fobs one is much more sensitive,( hair trigger ) than the other,perhaps she has a very sensitive one, that operates at the slightest touch,I have taken to checking my car is locked,then keep the remote hanging on its keyring from my finger,until I am far enough away to be sure I dont accidentally unlock it,before dropping it into my pocket....My other key fob has been no trouble...so perhaps your remote locking isnt faulty at all(With a bit of luck).....Jack.

sorry i haven't come back, ive been a little busy with operations and things, any way back walking again. ive found the problem, where my wife parked the car it was near a radio ham, the house had a very strange ariel on it, i looked into it to find out it gives off the same frequency as our key fobs. i park the other end now and all is ok

[Bobster]

Hi Gaz,

 

If you lock your car and then inadvertently unlock it, then the car should relock itself after 30 seconds if you have not opened a door.

 

Incidentally, I attended a conference at Thatcham recently and took part in an interesting demonstration. We all unlocked our cars with the remote, then the presenter pressed a button on a transmitter which operates on the same frequency as the key fob and none of us could lock our doors! The transmitter is a legal device which has another application but the police confirm it has been used to steal from cars; it works well against people who just walk away and hold the fob behind them. You really need to see the lights flash and hear the locks click and better still try one of the doors. If the fob does not lock the vehicle, you need to lock the car manually.

 

Best wishes,

 

Bob H

[gaztank]

The same fault happened twice to my wife, each time was near the radio ham, the first time she came back to the car after originally locking it with the remote. and the doors were unlocked. The second time she locked the car with the key. and when she came back the car was unlocked. it does not matter if you use the remote or key. the car can be opened by a remote after it is locked by the key. i looked in the radio frequency problems, the thing is car makers use a cheap radio system to work the central locking. every body uses the same frequency, eg garage electric doors, door bells, stairlifts, home alarm systems, (433mhz or 418mhz)etc. So when you get a radio ham with a dam great ariel parked on his roof, just the keying of his mic can unlock doors. so thats why we park the car the other end of the park and ride at the norwich airport.Not even the airports radio system effect the cars central locking, its only if you park next to the holt road near the helecopter hanger. so please everybody be aware of ham radio ariels near you, regards gary.

[paul.h]

We have what appears to be an amateur radio aerial not that far from us (about 200 m away) and occasionally our C3 locks do not lock on the remote or have been found unlocked - I put it down to some interference such as a mobile phone/mast but now possibly not. It would also affect our Xsara Picasso. The C5 and now C4 (Picasso replacement) do not seem to be affected though.