I got my Lexus is250 (2006 model year) about two years ago. Since I got it, I have not been able to use the keyfob to unlock or lock the car or open the trunk even after replacing the battery twice. I gave up on the issue and have been using the physical key rather than the fob to unlock the doors, and using the button on the driver door to lock it. When the car is powered off, none of the electrics on the car work, ie windows, trunk opening, door lock buttons, dome lights, etc. All of these functions work when the car is on. However, the keyfob has no issues starting the car and the red light blinks. I just found out today that if I press the lock or unlock button on the keyfob within 30 seconds of powering the car off it will work, but not after that. After reading up on some other threads I think the issue is a fuse. Is this something I can fix myself? If so, could anyone offer guidance on which fuse and how exactly to replace it?

If anyone thinks something else could be the problem, please let me know! Open to all suggestions (other than replacing the keyfob as I know that isn't the issue here) Thank you!

 

Have you tried replacing or checking these fuses?

Location: Fusebox 1 (driver side)
#16 SECURITY 7.5 A Smart access system with push-button start

Location: Fusebox 2 (passenger side)
#14 AM2 7.5 A / 15 A 2006-2010: Smart access system with push-button start

Or better off check all cabin fuses.

 

I'm thinking the 10A MPX-B fuse.... Engine compartment.

 

Let's hope it's only a fuse! But the behavior given was a bit off. It's sounded like that ignition circuitry that is only available for a couple of seconds after turning off the vehicle (includes power windows, etc.)

 

True, if it's not a FUSE it's going to be a painful recovery.

The key ingredient is the things that stay on after the ignition is off but the door hasn't been opened, showing that these items work. That's why I went with MPX-B fuse. It's a communication hub.
Some things it oversees.
Headlights, front fog lights, parking
lights, license plate lights, windshield
washer, horn, power door lock system,
power windows, power seats, electric
tilt and telescopic steering column,
meter, smart access system with pushbutton
start, outside rear view mirrors,
air conditioning system, multiplex
communication system

 

This was it! Replaced fuse #8 in the passenger side engine fuse box and now everything works perfectly. Thank you!

 

Nice! Glad that worked out and thanks for the follow up!

MPX-B FTW!

 

Damn, the guy "patiently" dealt with this for two years and 2013FSport fixed it in what.. a day or even hours? Very nice!

 

Thanks Man! Kinds words are few and far between around here. My day job is of engineering trade and I like to solve mysteries, so there is that. The flip side is that fuse popped for a reason. That isn't normal. Lets sit back and see what happens.

On to the next problem..... lol