Arsenii

Hello,

I am having troubles with my 2000 Lexus ES300's alarm system.
The thing is that if all the doors are unlocked, and I will press LOCK button on my remote, nothing would happen, yet if I will press UNLOCK button, the car will unlock. If I will lock all the doors from the inside by pressing lock button on the door panel, close all the doors, and this time press UNLOCK button on the remote, nothing would happen, yet if I will press LOCK button on the remote, the doors will lock. Also, if I would lock the car from the inside, I won't be able to unlock it using the same button, but if I will be persistent enough and press both UNLOCK buttons on the remote and on the door, doors may unlock. Please refer to the video.


I received this car with this issue, the previous owner stated that it went out when he got stalled in the middle of the road and took the car to a mechanic, which replaced an alternator with the refurbished DENSO one. The car also had some atrocious aftermarket parts that were installed really sloppily, which is the reason why I've had to replace the whole wiring harness under the dashboard. The alarm system did not work neither before nor after the repair.

In addition, alarm and trunk buttons do not work. I mean trunk button was working until I pressed an alarm button, which caused it to set off, yet after I shut it off, both trunk and alarm buttons quit working. Curiously enough, if I would hold the TRUNK button, the car will signal that it opened, but in turn, it did not. There is also still some chance that if I would disconnect the battery for quite a while both of those buttons may spring back to life, at least until I would set off the alarm again.

The biggest question is that I really love my car, so I do not have enough recklessness to just leave it unlocked, so I'm just closing it from the inside. The problem with that is when I go to unlock it using the key itself, it sets off the alarm, which means that I cannot have my horn working (for obvious reasons), it also burns my headlights and it is kind of a hassle to get in the car.
As a bottom line, if there is no obvious solution to this problem, I would really want to carefully (without cutting any wires or other wreckage like that, I just replaced the wiring harness that goes through the whole dashboard) disarm the stock alarm system, so I can at least have my horn back for some while before I would finally get to Lexus dealer to have it inspected, which would probably cost me a fortune...

Any help is greatly appreciated, thank you!

[UPDATE]: I was able to lock and then unlock the car using the key. What I did is locked the car from the inside, pressed a LOCK button on the remote to ensure that the car is locked, and went for a little walk (curiously, the car will not trigger the alarm if I would open the car right away); then I returned to it and opened the trunk with the button on the remote (it started working after I removed and then re-installed the "DOME" fuse), after that, I inserted the key into the door lock, and while holding the unlock button, I turned it to the unlock position - in turn, the car signaled that it is opened now (only the driver's opened though), and the most importantly, it did not trigger the alarm.

Any ideas?

Arsenii

Hello again,

I was finally able to solve the most frustrating problem that I have in my car! This problem kept me awake at night, but now I found a solution, and it is as simple as a driver side Door Unlock Switch.

After some research, trial and error, some dancing with the tambourine, I was able find a digital copy of the 2001 Lexus ES300 service manual, which has quite a lot of very useful information on how to diagnose certain things in the car. The part that I was mostly interested about was the alarm system Pre-Check, which tests the wireless function of the transmitter and the receiver. Mine tested good, but I still figured that there would be nothing wrong if I would try to replace it, since it is quite cheap anyway. And I did replace it, that is why I figured that I would need to reprogram a transmitter. That is when I realized that my driver side door lock got completely destroyed, it kept refusing to open and close during one of the reprogramming steps, so I figured that it will be a perfect time to replace it with the one that I've got from the junkyard a while ago. And that is where it gets interesting - that is when I saw something dangling near the door handle, that something was nothing else but a Door Unlock Switch, which got stuck in a closed position when it fell off the key tumbler............ This whole time the car thought that there was a key that keeps the door lock constantly closed, that is where all the problems came from, and now it finally works flawlessly! A sweet sweet victory..
I just saved myself a $150 on diagnostics and something unreasonable on repairs, and now I can have my horn back!

If you are interested, I was able to find Part Numbers for all three of those switches:

1. Driver Side Switch - 84903-33120
2. Passenger Side Switch - 84903-33110
3. Trunk Switch - 84903-33130

This problem did cost me a few decades of my life, so I decided to share the solution just in case if there is someone else who experiences similar issue.. Feel free to let me know if you have any further questions, I will try to answer them to the best of my abilities.. Also, I figured that I would not explain how to replace the switch itself, because there are already more that enough guides on how to replace the outer door handle, which is basically the same process. Again, just let me know if you would get stuck at some point and we will figure something out.

Hope you find it useful and best of luck!

speedkar9

It makes sense the door unlock detection switch is the cause of your car thinking its unlocked when it's actually locked.
I did a small teardown on the power lock systems in this video, you can see how I test it near the end:

Arsenii

Well, where were you before?? All kidding aside though, your video is really helpful, thank you!

Also, the car still uses tail and interior lighting (refer to the end of the video in the first post) to blink when it is locked or unlocked, is it how all ES300 work? If so, is there a way to re-route it to blinkers, since it is kind of frustrating to have all the interior lighting blink whenever I go to lock or unlock my car...

Thank you for help!