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Car Locks itself - 1998 Toyota Avalon

Dear Car Talk Community,

My 98 Avalon recently has been acting up: the car locks itself when I am driving, from time to time; sometimes, when I push my power seat, it locks, sometimes when I touch brake pedal, it locks, at this situation, I will constantly push button/brake 5-6 times to validate it is correlated. Sometimes, I didn’t touch anything, it also locks itself. And also, my remote cannot lock the car, but it can unlock the car. Furthermore, if I lock my car from inside, close the door, and then open the door with my remote, it triggers the alarms.

I know a short answer is it goes haywire. But I am just curious if there is anything I can do. I forgot to mention I live in freezing upstate NY, and this problem happens since this winter. It also happened to my 2001 Toyota Sienna, in winter, but it cured itself somehow. Also, I love washing my car in the automatic wash, so maybe the strong water gets into the system. But I already stopped wash my car,

Live in the north, if you don’t wash your car, it rusts away, if you wash your car, it haywire.

Thank you for reading, if you have any suggestions to make my life easier, please let me know, I am carrying two sets of keys now just in case I lock my self out.

Best regards,

Jay

Remove the battery from your remote. If the haywiredom stops, you have a bad remote.

Open the door and inspect the areas around the latch and hinges. You should see a little button you can press in, and it pops out when you release it. That’s the door switch. Should be one on all doors and possibly the hood and trunk too. Sometimes one of those switches will get gunked up, which can cause weird symptoms. I doubt this is the problem given the nature of the symptoms, but it is a pretty easy thing for the owner to check all the door switch buttons push in and pop back out smoothly and aren’t sticking. When there’s a problem w/a door switch it usually occurs on the drivers side door first b/c that door is used the most, so if nothing else check that one.

Is this a factory alarm system? It sounds to me like it is either wired incorrectly or there is an issue internal to the alarms control unit.

It almost sounds like someone wired the alarm lock (arm) wire to the stop light switch…either this happened by wiring or an internal fault in the alarms control unit. When you are inside the vehicle and lock the door are you using the remote to do so? Did you lock the door while it was open…if so, you cant do the test that way.

When you open the door lock with the remote it should disarm the alarm and unlock the door… It is unlocking the door but not disarming the alarm… Again, wiring or an alarm control unit issue. I would be looking into the arm/disarm/ lock wiring on this vehicle. I would also look into the behavior of the alarm when you use your key in the drivers door… It should lock and arm the alarm or unlock and disarm just using the key in the drivers door. If your system was fine before all of this…then it points to the alarms control unit going haywire (rare-ish).

I used to install alarms professionally…so I’ve been down this road many times. But to try and guide you via the internet is a fools errand… Just too much to try and type when the solution is in the wiring and alarm brain…there are tests to go thru… This is one of those things best solved onsite, sorry.