Key fob problems

[aclivity]

My wife's Kia Sedona (05 model) has just stopped responding to the remote blipper for the central locking / alarm. First thought was that it would be the battery in the fob, so got the spare, the only difference is that the spare fob LED lights up brighter than the main set of keys fob.

I've locked with the key for now, but that leaves the alarm off, and is not very convenient either.

As both fobs stoppped working at the same time, I suspect something wrong on the car side, rather than the fob side. There is no obvious "RF receiver" fuse label in the fusebox, short of taking each fuse out in turn and inspecting it, anyone know if the fuse for the alarm / key fob is specifically named? Anything else I should check (other than trade in values! )

[fflyingdog]

You could try disconnecting the battery to see if the alarm will do a reset.

[aclivity]

fflyingdog said:

You could try disconnecting the battery to see if the alarm will do a reset.

Tried that just now - still no luck.

I guess I will have to call the garage tomorrow as all of my skills and knowledge are now exhausted.

[aclivity]

strange happenings today.

Guy over the road mentioned that his wife's TT keyfob had stopped working. Another guy a few doors down had the AA out to his car, as he couldn't turn the alarm off, so whenever he started the engine - alarm went off. All within 70 yards of each other, all at the same time.

Just tried the fob as I was locking up - car beeped and locked.

So - short duration highly localised RF failures on keyfobs.

Aliens?

[Mr Happy]

Possibly an RF jammer situated somewhere close by unscrupulous types trying to catch people unaware and gain entry into their cars?

[aclivity]

Mr Happy said:

Possibly an RF jammer situated somewhere close by unscrupulous types trying to catch people unaware and gain entry into their cars?

If they were, they must have been in one of the houses, as there are no places to "hide" on the road - it's a wide road, open plan front gardens. If they are going after the cars, I think they will go for the TT and the Range rover before the Kia Sedona!

[Mr Happy]

aclivity said:

If they were, they must have been in one of the houses, as there are no places to "hide" on the road - it's a wide road, open plan front gardens. If they are going after the cars, I think they will go for the TT and the Range rover before the Kia Sedona!

That's the nub of it, they can be concealed in something as small as a cigarette packet, and stashed in a nearby hedge. They're not discriminatory. They block the 27mhz frequency in a localised area, which is why it could have had interfered with your car and those of your neighbours.

[Rowan138]

those jammers are tiny, i in fact recently found one which had been put into a small waterproof box and hidden at the base of a telegraph pole. i used a radio scanner and a directional antenna to find it as several car alarms and other rf stuff in the local area was acting up!

[rs4al]

How odd, as when I got home last night, the car would not respond to the key fob for around 10 minutes, then it worked !!

How can an RF jammer give thieves access to the car ?

[DrTre]

At a guess they don't give access but instead people leave their car locked by the key which possibly doesn't arm the alarm?

I'm making the assumption locking by key doesn't set the alarm....if that's true, is there any reason for that?

[TonyRPH]

Mr Happy said:

...
They block the 27mhz frequency
...

Most (if not all) keyfobs operate at around 433Mhz, and some of the newer ones are on an even higher frequency (around 900Mhz I think).

I used to frequent a pub near an airport, and usually my fob would stop working there, most likely to due RF interference from the airport.

OP, do you live near an airport, or do you have any mobile phone masts nearby? (or any other communications type masts?).

It could be sporadic interference from those, particularly if a fault has developed in one of said masts.

[Dan_The_Man]

There is a household item that when it goes faulty it acts as an RF jammer (caused my street the same problem - no one could blip the central locking) however I can't mention what it is as my previous posts on the subject were moderated - don't want the bad guys to know.

[swisstoni]

I had this a few years ago with a Volvo XC90. It was correctly diagnosed by the AA man as some kind of RF interference.

After much head scratching as to the cause I found it to be caused by a video sender I was using to transmit tv to an upstairs room with no aerial socket.

So the cause may not be sinister. More likely some normal home gadget in your home or a neighbour's.

The area where the jamming occurs can be quite small too. Moving the car even a couple of yards can be enough to get out of it.

[aizvara]

I've had on and off problems of this sort with a "household item" in my house; I'm pretty sure its the ethernet powerline adaptors, as when they on I often can't open or lock the car until I am standing right next to it.

[Mr Happy]

TonyRPH said:

Mr Happy said:

...
They block the 27mhz frequency
...

Most (if not all) keyfobs operate at around 433Mhz, and some of the newer ones are on an even higher frequency (around 900Mhz I think).

It would be trivial to block all of the regular frequencies. That's not quite the point I was making though.