Electric problem, key fob not working

I have a 2007 Lexus is250. I believe it has electric problems so I went to dealer they said they have to remove the dashboard to check all the electric wiring, which will cost me more then a thousand dollars. So I decided not to.
The problem is with the key Fob. I replaced the key fob battery and the car battery have more then 12v reading.
Right after when I turn off the car, the key fob will work for less then 30 seconds. So right after i turn of the engine I have to lock the car immediately otherwise it won’t lock via key fob. Which means when i turn off the engine it turn off everything, in modern car when we turn off the car it still uses some electricity to keep all the computers and key fob alive.

In my case it does not stay alive. That’s why i think my key fob is not working because my car doesn’t draw any electricity when I turn the engine off.

Anybody have any solution to fix this issue? I appreciate your response. Thank you.

Are there any atermarket additions to the car? Remote start, alarm, radio etc.?

Nothing aftermarket, everything is original in the car

I am familiar with Smart Key operation on this vehicle. If the Remote Keyless Entry operation stops 30 seconds after switching off the ignition, when you return to the vehicle how do you unlock the doors?

Do the black buttons on the door handles work after the RKE has stopped working? Do the door lock switches on the door panels work long after the ignition has been switched off?

All of the answers is no

When i return to the car i have to unlock using the mechanical key even the black button on the door handles doesn’t help. But i never have problems starting the car

No the door panel lock switch doesn’t work after i turn of the car

That is troubling, both Smart Key operation and RKE do not operate but the door locks operate as they should when the ignition is on? Cycle them at least 5 times to see if each of the locks function and are not weak.

When ignition is on only the lock switch on the door panel operator normally. When i am sitting on the car and the ignition is on and If i push the lock or unlock button on the remote it does not do anything, but the little light on the remote light up every single push. So the only time when remote works is right after I turn of the car. And it work of less then 30 seconds

With the number of computers involved with door locks and smart key operation this becomes a complicated system to diagnose, a Tech Stream dealer scan tool will be needed to perform diagnosis.

I suggest you check the memory power fuse along with the rest of the fuses under the hood to make sure there aren’t any blown fuses. I suspect you will find that the memory fuse may be blown out.

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I am experiencing the same issue, only addition is that the trunk opening function and panic button are non responsive as well. I will check the fuses to learn were there maybe a fix. Don’t have the computer mentioned so will have to try to resolve via fuse trail for now.

Do you own a Lexus? If so, what year? If not, what car brand, including model, and what year? When did you replace the FOB battery, and did the no start condition start right after that?

2007 Lexus IS250 4door, I do know that my door sensors are going out so not sure if there is some relation. I have check both the fuse panel and fuses on the interior and the engine compartment and no mini fuses are blown.
Someone mentioned to check a memory fuse but when I check the manual I am unable to find the part on the fuse panel listings.

  • Key fob has a new battery
  • Car battery is between
  • Fuses are all good

Does the red light on the Smart Key blink when you push/hold the unlock button?

I assume that you only have one fob to test with and nothing responds on the car when you press any button on it. If that is the case I would suspect a bad fob or it needs to be reprogrammed to the vehicle.

Between what?

(Nevada 545)
(es the red light on the Smart Key blink when you push/hold the unlock button?)

Yes, when the buttons are pressed the light does blink about every 2seconds. There is no change if trying to unlock, lock or open the truck.

(Cougar)

I assume that you only have one fob to test with and nothing responds on the car when you press any button on it. If that is the case I would suspect a bad fob or it needs to be reprogrammed to the vehicle.)

This makes little sense, there has been no leading indications that anything has led to what would cause this? Neither my battery of key fob battery had died.

(JTSanders)
(Between what? )

Sorry spell check auto correct. The car battery is functioning fine. It has not lost its charge.

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