How To Turn Alarm Off With Just The Key?

[zoom jones]

I have a '01 Rav4 VX. This morning when I set off it took a while for the remote to blip and unlock. Lot's of button presses. Eventually it worked and I came to work. Jumped out and locked the car behind me. Wasn't happy with my parking so decided to shuffle over a bit. Could I unlock the car with the remote button? Could I heck! Repeated tries resulted in nothing.

I managed to open the door with the key but the alarm just went off eventually stopping when I closed the car and locked the door.

Is there a way to switch the alarm off with the remote?

[daveh_rav4]

Sounds like the keyfob batteries have gone a bit flat (reduced voltage); try replacing them and resync the fob to the alarm. That should do it!

DaveH

I have a '01 Rav4 VX. This morning when I set off it took a while for the remote to blip and unlock. Lot's of button presses. Eventually it worked and I came to work. Jumped out and locked the car behind me. Wasn't happy with my parking so decided to shuffle over a bit. Could I unlock the car with the remote button? Could I heck! Repeated tries resulted in nothing.

I managed to open the door with the key but the alarm just went off eventually stopping when I closed the car and locked the door.

Is there a way to switch the alarm off with the remote?

[zoom jones]

Sounds like the keyfob batteries have gone a bit flat (reduced voltage); try replacing them and resync the fob to the alarm. That should do it!

DaveH

I have a '01 Rav4 VX. This morning when I set off it took a while for the remote to blip and unlock. Lot's of button presses. Eventually it worked and I came to work. Jumped out and locked the car behind me. Wasn't happy with my parking so decided to shuffle over a bit. Could I unlock the car with the remote button? Could I heck! Repeated tries resulted in nothing.

I managed to open the door with the key but the alarm just went off eventually stopping when I closed the car and locked the door.

Is there a way to switch the alarm off with the remote?

No doubt. Unfortunately though I'm at work and don't have the luxury of being able to get away, get batteries and replace etc.

I can get the spare set couriered from home but I just wondered if there was a quicker route to earth to get the alarm turned off.

I had heard disconnecting the Battery, leaving the key in the ignition and then reconnecting the Battery might work?

Also - where is the infrared receiver in the car? If I can get close enough I maybe able to disarm the alarm by getting a bit closer.

[bitman]

what happened with our rav 4 is that when you open the door by key only the alarm will go off and the indicators will flash. when you then ignore the noise and start the engine the alarm will stop and you can drive away.

when you stop the engine and lock the door with the key only it will lock the doors and re-arm the alarm again (no sound).

the same thing happened also with a 2003 c-class merc i once had, daughter opened the doors by key only.

hope this helps

[zoom jones]

what happened with our rav 4 is that when you open the door by key only the alarm will go off and the indicators will flash. when you then ignore the noise and start the engine the alarm will stop and you can drive away.

when you stop the engine and lock the door with the key only it will lock the doors and re-arm the alarm again (no sound).

the same thing happened also with a 2003 c-class merc i once had, daughter opened the doors by key only.

hope this helps

Thanks - I did start it after the alarm had gone off. So will the alarm stay off then? Me driving it won't trigger it to go off again!? Blimming nuisance this and had to happen on a Friday when I want to get off for the w/e.

[bitman]

what happened with our rav 4 is that when you open the door by key only the alarm will go off and the indicators will flash. when you then ignore the noise and start the engine the alarm will stop and you can drive away.

when you stop the engine and lock the door with the key only it will lock the doors and re-arm the alarm again (no sound).

the same thing happened also with a 2003 c-class merc i once had, daughter opened the doors by key only.

hope this helps

Thanks - I did start it after the alarm had gone off. So will the alarm stay off then? Me driving it won't trigger it to go off again!? Blimming nuisance this and had to happen on a Friday when I want to get off for the w/e.

no it will stay off so have a nice weekend.

take a small phillips and visit a maplin shop to source a new Battery and your all done in minutes

[cheetah1]

It's not infrared, it's by radio.

Thinking reasonably, the computer should understand that you in fact have the key, when the immobilizer doesn't stop the engine again after starting it, and therefore turn of the alarm.

Try it and you'll know. :)

[abraxas]

This probably doesn't apply here, but...

I remember that someone told me not to press any buttons when changing the Battery in a key fob of my old BMW. This way I wouldn't have to re-synch it to the car's ECU. Probably nonsense, but I did change the Battery in the fob and it did not need sync-ing back. I think the going rate for synch was something ridiculous like 60 notes for BMW so I remembered the "trick" Can't hurt, really...

It kind of does make sense. If I was designing a fob, I'd never just assume uninterruptable contact with the battery; and I'd allow for power interruptions without having to go back to the dealer to synch it. (Like dropping the keys, etc.) Now why would pressing a button on a non-powered circuit make a difference is beyond me though... So, I'd better run away now before schm comes in and tells me off for talking nonsense 'bout electronics. :)

[cheetah1]

This probably doesn't apply here, but...

I remember that someone told me not to press any buttons when changing the battery in a key fob of my old BMW. This way I wouldn't have to re-synch it to the car's ECU. Probably nonsense, but I did change the battery in the fob and it did not need sync-ing back. I think the going rate for synch was something ridiculous like 60 notes for BMW so I remembered the "trick" Can't hurt, really...

It kind of does make sense. If I was designing a fob, I'd never just assume uninterruptable contact with the battery; and I'd allow for power interruptions without having to go back to the dealer to synch it. (Like dropping the keys, etc.) Now why would pressing a button on a non-powered circuit make a difference is beyond me though... So, I'd better run away now before schm comes in and tells me off for talking nonsense 'bout electronics. :)

I'd guess there are capacitors powering the memory cicuit when you take the Battery out, and when you press a button you discharge the capacitors pretty much instantly? Just guessing, though. Wouldn't life be much simpler if everyone used EEPROM-memory circuits? :)

[shcm]

So, I'd better run away now before schm comes in and tells me off for talking nonsense 'bout electronics. :)

Nah, they are all valid comments

It's swings and roundabouts taking the Battery out really.

There will probably be a capacitor somewhere in the fob across the Battery. This will hold some charge. Most of the time, the fob will be in a low power state, drawing very little current. With the Battery out the charge in the capacitor may be enough to sustain it.

When you press a button, the fob will wake up and probably draw a bit more current, (there may still be enough charge in the capacitors to sustain it with the battery out). It might do some calculations, then it will turn on its transmitter, which will draw significantly more current. This will most likely deplete the charge before the transmission can start and the fob will finally be without power.

So, yes, your comment about not pressing the button while changing the battery quickly can be valid. It may run on without noticing.

However, there is another side. You take the battery out. You still have charge in your capacitor, but it is slowly being drawn away. The voltage droops away slowly. It's digital electronics and as the voltage drops, it will reach a point where parts of the chip internals may work and others may not. This is quite bad for digital things and you can end up with very strange looking faults or behaviour.

It's easily cured by removing all the power (i.e. pressing a button will deplete the charge completely) and re-applying it (inserting the battery). That way the electronics usually gets an internal reset and all will be well. However, it will now be out of sync. This way at least you are starting from a good know state and is probably why a lot of manufacturers tell you to do it, but you can try the first method first I suppose.

You can detect low battery voltage and force the digital stuff into reset. It just depends on the fob (and cost!).

There are usually simple (or there should be!!!!) re-syncing procedures, its just a matter of knowing what they are. Sometimes just a case of RTFM. If the system joins together both the transponder (for starting) and the fob (such as in keyless entry systems), then there is no reason why the car can't do the re-syncing process, transparent to the user.

Been there, done that, designed the chip and got the free gifts from the chip manufacturer! :) - So I could go on and on and......................................

[shcm]

Wouldn't life be much simpler if everyone used EEPROM-memory circuits? :)

Yeah, maybe. For security reasons it all really has to be embedded in one chip. That's doable. Possibly the write current may shorten your Battery life and you are looking for real low power consumption here. E2 also used to have limited re-write life. Much better now. There's never any one clear way, you have to balance all the design constraints spec, cost, etc.........

[tropical_Z]

I had a scenario a while back, when the alarm was active when the unlock was pressed. ie, the alarm noise and indicators blink until you drive off. It continued for a few days, but corrected itself when the unlock button was pressed whilst key was in the ignition - I still dont get it!