Why do my car windows go down by themselves? There are a number of reasons why this may happen. It is important to know the reason before you start trying to fix it as some can be very dangerous and should not be done by yourself.
Car battery failing
The first possible cause would be that your car battery is failing. This will usually mean that all your electric windows go down at once or one window might go down and then another and so on after a few minutes. If all the windows do this then there is very little chance that it’s anything but a failed battery and you need to get it replaced as soon as possible.
Broken electrical wing
A second possibility would be if your electrical wiring has become broken. This can happen quite easily, especially in older models, where rust starts corroding away components, making them ineffective. This can mean that all your windows go down at once. If this is the case you will need to look at replacing the wiring or have it repaired by a qualified technician.
Excessive heat
A third reason could be caused due to excessive heat. This isn’t usually a common problem but if the heat of summer has been particularly bad and combined with perhaps letting some air out of the tires it may cause some electrical components too come loose and thus allow an electrical short-circuit, meaning all your windows suddenly go down at once or one window goes down after another until they are all pushed down. To reduce the chances of this happening you should not let all the air out of your tires, ensure that rust is removed from any areas where there is the possibility of it causing a problem, and make sure all your wiring is secure and in good condition.
Defective Controllers
A final reason could be due to defective window controllers or actuators, again this is unlikely but it’s always worth checking as sometimes they can really go wrong and cause strange problems like this. It is also possible if you have had some work done on the car that the new controller or actuator hasn’t been installed correctly and faulty itself. If you check all these other possibilities then most likely this will be what has happened.
Conclusion
If after checking these points, you notice nothing wrong with them then there is one more possibility left; someone may have pressed buttons on the key fob while the windows are down thus pushing them down further into their position. If this is the case then you will need to replace them, but ensure that they are installed correctly or more windows may become stuck in future.