General Why do my doors unlock by themselves?!

[keithodulaigh]

Hello,
The electronic key for my Punto (2004 1.2 Active) flashes the red light occasionally and this is unlocking my doors! The light flashes about 3 times. I thought that the battery was dying but it measures about 2.9V which is alright IMO.

This has happened when the key is lying on a table and there is absolutely no possibility of something hitting the button.

It's obviously a bit of a security risk so has anyone else had the problem or any ideas on how to fix it?

Thank you!

 

[Oll1e]

Something is obviously shorting out inside your keyfob.

Mite be something simple like a bad solder joint or damaged wire.

Carefully open it up and take a look for anything that looks like it shouldnt be there. Since its intermittant it sounds like theres a bad joint or something lose to me.

 

[DaveMcT]

Mine wont lock when there is a door open, but the fault does sound like the fob circuit. Use a good magnifying glass and look for any solder that looks grey or crystaline. Unfortunately the circuit is tiny so re-soldering could be "fun" and you risk wrecking the cct board.

 

[Eklipze3k]

Before potentially wrecking the circuit board, just do a test first - take the battery out of the remote key and for a day or two just use the normal key for un/locking the car. If there are no occurences of random unlocks, you can be sure it is the remote key (which it does sound like). Otherwise you'll know it's something within the car itself if it keeps doing it.

 

[Oll1e]

well you can be 100% sure its the fob if the little red light is comming on at the same time the car is unlocking because its only supposed to come on when a button is pressed indicating that something has shorted to replicate the button being pressed.

Plus there isnt 2 way communication between the fob and car so the light wont flash on the fob if u unlock the car with a key because the car dosnt talk to the fob, only the fob to the car.

 

[keithodulaigh]

Thanks for the replies!

I only got the car and the the button on the fob had no blue rubber protective strip so my guess is that maybe the button is at fault...the rest of the circuit looks fine...

When I push the button it doesn't feel like it bounces back either so maybe the spring inside the button is ruined...I think I'll try replace the button , if I can find one that's a suitable size.

 

[deeinlondon]

Is it possible a car can unlock itself?

I'm 100% certain my 2001 Punto Sporting MK2 has been locked and I come back to the car and it's unlocked itself .. could it be something to do with the very cold weather? or possible water leak as the passenger side of my foot well was wet previously?

 

[Ziggy122]

Is it possible a car can unlock itself?

I'm 100% certain my 2001 Punto Sporting MK2 has been locked and I come back to the car and it's unlocked itself .. could it be something to do with the very cold weather? or possible water leak as the passenger side of my foot well was wet previously?

Yes it can
I had a car that kept locking itself when i just unlocked the sodding thing

A Short in the Doors actuator can cause weird results

Even a wire thats slowly rubbing on a chassis somewhere can often make the car think its needs to unlock

Ziggy

 

[deeinlondon]

How did you solve your problem?

I'm worried now about leaving things in the boot if the doors are going to unlock themselves .. we once caught someone walking from car to car in our road at like 3am trying the doors of cars parked in the road.. they even came on to our drive way to try the door locks to see if they would open.