Car alarm/remote problem

[Osem]

Until a couple of years ago I was using the normal key to open/lock/alarm my car. Locking is a 2 stage process with the first key turn visibly setting the locks (and possibly activating/deactivating the alarm/immobiliser?) and a second turn operating the deadlocks. Over a period of time I noticed that the key wouldn't always work properly in the driver's side door (DSD) and trying to open it would sometimes set the alarm off and wouldn't set the deadlock. I'd never used the supplied fob but found it in the drawer and started using it to get around the problem. Apart from putting in a new CR2025 battery a while ago, this was perfect but in the last few days the fob started to play up and this morning wouldn't work at all. I replaced the battery again but it still doesn't work so I'm wondering what's wrong (there's no LED on it so no way of knowing if it's working). After fiddling around a bit it seems that if I use the key and just lock the DSD once (I'm assuming the alarm isn't set?) I can then reopen it again using the key without any issues but if I double lock the car properly using the key in another lock if I then try to open the car again using the key in the DSD the alarm will be set off.

It's an old car and not worth spending much money but I'd be interested to know what any car-techie-folks around here think might be wrong and if there's a simple way around the problem other than what I've described above. Ideally I'd like to get the fob working again but can't see any sign of what might have gone wrong with it (e.g. water or battery damage).

TIA as always.

[raging bull]

Like a computer, try disconnecting the car battery for say 10sec then reconnect.
(First making sure you have the security codes for radio!)

[Gary L]

I bet it's a Vauxhall. I know how to fix it if it's a Vauxhall.
but he can't see my posts

[rhyds]

What car is it, and what age?

One thing to note: On Rovers, sometimes the keyfobs can lose sync with the car, and you end up having to hit the lock or unlock button about 30 times for it to resync.

[Osem]

Originally Posted by raging bull

Like a computer, try disconnecting the car battery for say 10sec then reconnect.
(First making sure you have the security codes for radio!)

Will happily give that a try but ill have to scout around for the codes first. Do both battery terminals need to be removed?

It's a 2003 Mazda.

@ Rhyds - yes I've discovered there are various ways to 're-programme' remotes etc. often involving key sequences and operation of the door locks. I haven't found one for my car but would be a bit worried about mucking something up unless the instructions were from a trusted source.

[rhyds]

Hmm, mazdas can be tricky. Sometimes they use shared Ford kit, other times its their own unique stuff. It depends on the model really.

Can't help much either way sorry. My first thought would be to check/clean the electrical contacts in the door lock to solve the original problem, but I've no clue with regards to the fob

---------- Post added at 16:12 ---------- Previous post was at 16:09 ----------

I'd also try some of the mazda forums (especially if there's a model specific one).

[raging bull]

Does it not say how to re sync a key fob in the car handbook?
My central locking relays are under the front seat, Vauxhall Meriva.
Just take off the +battery lead to reset central locking, assuming relays are o'k.

[Osem]

No there's nothing at all about that sadly. I can get by at the moment but it'd be good to get the fob working again. Hopefully it's just a problem with the one door lock and the fob, not a sign that the system's going funny.

[rhyds]

I'd imagine its wear in the switch contacts in the door lock (which allows the door itself to lock/unlock. but the alarm doesn't get an unlock signal), or a wiring issue. If you've got the patience it might be worth taking the door card off and checking/cleaning the cabling and contacts/connectors.

[richard s]

Hi Osem

Just remove the negative terminal... if you have a factory radio fitted get the security code for it to hand because once disconnected (it will think it has been stolen and will not work without the security code).

Does your boot or any other door locks - lock on the from the key fob.