My keyless entry ECU seems to have gotten confused. It detects when I am near the drivers door and enters into a loop of locking the door. The only way I can get in is to hold the unlock button on the fob. It enters this loop as soon as I get near. I don't have to touch the handle. Then when I do get into the car it long beeps and starts telling me "Key detected in Vehicle". This all started around the time another owner of an IS300h mistook my car for his and tried to get in.
Everything works fine on the passenger side. Wiring was checked by Toyota dealer (No Lexus dealer nearby) who said the wiring etc looks to be fine but he thinks the ECU would need to be replaced but it would be expensive. Is there any way to reset this ECU or something and re-pair my keyfobs to it?
Any help would be greatly appreciated as it's a real pain, I can't find anyone with the same issue online, nearest Lexus place is a two hour drive and even if I wanted to trade in or sell this car sometime I can't really in this condition. Thank you.

 

Welcome to the forum!

From your statement "Everything works fine on the passenger side" I take it this only happens when you approach the drivers door?
If that is the case, and everything works normally on the passenger side, then the issue is not the key or the ECU.
Think about it...if you are approaching the vehicle with the same key on the passenger side and the drivers side, and there is only one ECU in the car with the key code, then why would it be ok on the passenger side but not the drivers.
Considering you said that this started after something mistook your car for theirs and was trying to get in (assuming on the drivers side), I think the issue is the drivers door handle.

The drivers door handle is what contains the touch portions for Lock and Unlock as well as the antenna for the key.
If the touch portion for the Lock was damaged it would only start acting up when you approach the car with the key, because without the key near, the car won't Lock or Unlock from the touch portions.

Simple test to see if the vehicle stops doing this...remove the drivers door panel and unplug the handle. This will disable the touch and antenna functions of the handle.
When you approach the drivers door now, the car should do absolutely nothing. And if that is the case...replace the handle.
Likely the person trying to get into the vehicle was a little aggressive with the handle and damaged it.

The other long shot is that there is something on the handle that is making it think it's being touched when it's not...but that should be seen fairly easily by checking the top and bottom of the handle.

 

Thank you. I appreciate the reply. I will definitely try this. This issue has been going on for about a year now. My work colleague who tried to get into the car has since sold his IS300h but he loved that car and I would doubt he would be aggresive with it but still I think you might be right that somehow the handle may have gotten damage. I had already check it for dirt and debris adhered to the sensor but it's clean as a whistle.
Curiously during the winter months it simply stopped detecting when I was close and never went into the cycle of locking but then as soon as the summer came and the weather started to dry up and heat up it started into looping the locking again.
Do you know is there a particular place on the internet or somewhere where I could try to buy a replacement door handle? Because there is no Lexus dealership nearby not many people drive these cars so there aren't many places I could try for parts.

 

Do you know the color code for you vehicle? Or what color your vehicle is?
I believe the handle comes pre-painted from Lexus.

 

The latest update:
During the winter when it was very damp/cold my keyless entry on drivers side did not react at all.
During the spring and early summer when it was warmer and dryer it was reacting but it was going into a loop of continuously sending signals to lock the doors.
We have just had a heatwave for about two weeks and now it is working perfectly and unlocking when I touch the sensor.

Could it have been dampness inside the door somewhere that was causing problems that has now dried out or something?
I'm still not sure of the root cause or if there is something I could do to keep it working.

Thank you.

 

If it's working now there really isn't anything to check.
My money is still on the handle itself.

 

Hey, did you ever sort this? I've the same problem

thanks

 

Nope. I never figured it out. As usual Keyless entry was totally not working all winter. Now that it's starting to get warm my keyless entry is back to its seasonal loop locking any time I get near the drivers door. Any joy at your side? Another strange thing is that the AC stopped remembering the previously set temperature but again when it got warmer that came back. It's like the two may be linked but I'm not sure how.

 

Swap the handles (put the passenger one on the driver side) and see if that problem still happens.
That way you're 100% sure it's the handle and you can order a new one.