Hi,

Before I discuss a reprogramming "how-to" I found, here's the scenario:

For whatever reason, on my second/spare key fob (that is seldom used), has stopped locking the doors consistently. It will still unlock every time. I checked the CR1616 battery (only one year old) and it it good at well over 3v. I also swapped the battery with primary key fob's battery (which has a bit lower voltage but still over 3v), and have the same no-unlock issue on the 2nd fob. This morning I tried that 2nd fob again, and this time it unlocked the doors no problem as usual, and then it allowed me to lock the doors, but only one time before it quit unlocking the doors on subsequent tries.

With the good primary fob, over the last year, I've noticed that when I lock the doors, it frequently sound like a 2-step operation is happening: I here a clunk like the locks (actuator?) going down, and then about a second later, another clunk/click, like it's actuating again. Another anomaly is that the "beep" when locking, is usually not sounded anymore. Ditto with the missing unlock beep. So that's the scenario I'm working with. That said, now back to the 2nd fob that will no longer lock.

The 2nd fob's buttons all look good (like new) and click nicely. So I thought maybe somehow it's lost it's programming. I researched a bit and find this article titled "How do I Program Lexus RX300 Keys?", by Michael Butler at:
How do I Program Lexus RX300 Keys?

That appears to be a nice comprehensive article that covers add mode, rewrite mode, confirmation mode and prohibition mode.
Does anyone know if that procedure looks correct (for reprogram mode in particular).

Thank you for any comments, suggestions or corrections that you care to provide. I appreciate your help.

Regards . . .

 

I know that there is a thread somewhere on this forum that enabled me to program a replacement valet key, and it worked the first time. If I find it I will point you to it; the one you cite is not the one I used.

 

Check the March 17, 2003 post by 'GP1200X' titled "Keys for the SUV." I think the section on 'New CUT Keys' may be what I successfully used.

 

There are multiple things involved in the key lock/un-lock operation listed below in the order of most frequent to least frequent.

Safety disable [Remote stops responding when it receives signal from another remote key. It resets when you use the actual key. Parking lot scenario]
Key-Fob battery [can be eliminated by led glow one the key-Fob]
RX lock actuator .. [can be eliminated or confirmed by the lock/unlock button (not the ****) inside the cabin driver/front-passenger .. most frequent problem based on age/use]
Key fob transmitter. [lint etc]
RX receiver.
Programming.

Programming is way at the bottom and all others must be explored/investigated before tinkering with it. I only recommend this extreme action when you have a new key.

Our resident expert is 'hyperwish' and he has posts in the DIY section. In the actual thread many members have used and verified the procedure.

Salim

 

Thanks JAB! I'll certainly review that : )

 

Thanks for sharing your expertise once again salimshah. It looks like I need to do some more testing on this. I hear you about reprogram being last option.

I'm not sure that I understand the "Safety disable" feature. Could you elaborate a bit or is that described in one of the manuals?

Regards . . .

 

This is a simplistic description, in actuality there are more safeguards built in. There is a base transmit frequency [like the FM/AM station] and information that rides on the base frequency. The base frequency is 'tuned in' and the information sends handshake and commands.

When the remote based lock/unlock started, there was a concern about folks using a scanner and capturing your RF signal and then use a transmitter to resend the signal to unlock your vehicle. A simple but elegant solution was built by Lexus [others may have done this too] is that once a vehicle receives the base frequency and if it does not get personalized signature, it will be disabled. So if the villain tries to send the unlock signal and does not have the right signature on the first try then the system shuts off. Usually the villains would have, what we call a sweeper, which tries to send different commands and hopes to be lucky. With the built in safety, further attempts are blocked, till the owner uses the actual key to unlock.

Parking lot scenario is say when two or more Lexus owners approach their parked cars. The vehicle of the first owner to arrive on the scene will receive the signal and unlock. [Each vehicle has a personalized code ... to be exact it is like a key and there will be matching keys but the likelihood of same key in the same region is controlled and remote]. The other parked Lexus will receive the base frequency and not the right code and it will shut off the receiver. When the second owner approaches the vehicle and uses the remote .. nothing happens till the actual key is used in the door.

Another safety feature is to limit the range of the receiver. 2nd ben GS circa 1998, one has to be right next to the vehicle to use the remote. Consumers did not like it and now they want to use the confirmation to locate their vehicles. '99 RX has much longer range. Current models use more friendly but elaborate safety remote options.

This is the reasons when people loose their key, I tell them to get the key made as relying on just the remote may leave them locked out.

There is lot of engineering and thought process put in the building of vehicles and one feels amazed at the human ingenuity the more we study it. Granted we have to thank the villains to force us in the path of prevention.

Salim

 

Hey Salim !

What a reply! I had no idea there was an engineering degree required to understand this. But you certainly did a great job explaining it in a manner that even an old knucklehead like me can understand. Kudos to you my friend!

Regards . . .

 

Hi salimshah (and JAB),

Nine months later . . . I have solved one of the mysteries of this thread. In my original 5/19/2019 post above I said:Here's why sometimes, but not always, I do not hear a beep when locking the doors: It believe this is by design! Here's why I say this:
If one (or more) of the door lock actuators is stuck in the unlock position, there will be no beep when using the key fob to lock the vehicle. This is to silently warn you that you may have an unlocked door.

Here's the test: After using the fob to lock the doors, and not hearing a beep, I walked around the vehicle and tried to open all the doors via the door handles. I found that the passenger-side right rear door was still unlocked!. I opened that unlocked door, and manually enabled the door lock rocker on the interior door handle (ie. lock the door). I closed the door and tried to open via the exterior handle and verified that it was now locked. Now I tried the fob again to lock the door: Joy! Now I heard the beep and the parking lights flashed like they're supposed to.

I found this out quite by accident: Last week I locked the doors with the fob, and as usual, I'd hear a clunk clunk, no beep, and no parking light flash. Then I cleaned up something in the driveway for a couple minutes. Then I walked around to the passenger-side rear door to get something out of the vehicle. It slipped my mind that I had only minutes ago locked the vehicle, and I just grabbed that door handle and it opened (it was supposed to be locked). Then I immediately remembered that I had just locked the vehicle, and all doors should have been locked.

Also - In retrospect, the clunk clunk I was hearing was that actuator on the passenger-side rear door not fully completing the door lock assembly's locking operation.

And the scary part: For nine months, when I didn't hear the "beep" after locking via the fob, the vehicle was wide open for five-finger discount business. I was just lucky no one was trying to shop via that particular door. So until I get time to deal with the sticking actuator, if I don't hear the beep, I just walk around and manually lock the door via the rocker.

Hope this helps someone else.

Regards . . .

 

Brcobrem:
The audio beep is a confirmation. When the "lock of all doors" does not happen, the system cycles through and unlocks itself. That is exactly what you heard when the door locks unlocked [Sad part is that if the other doors were locked, your fail to lock with the remote would most likely unlock all doors. [I have used most likely as the lock/unlock action is set by the dealer at delivery [first gen Rx]. ].

Salim

 

Hi Salim,

Thank you so much for your clarification of the lock/unlock cycle noise I am hearing. I will just add that I checked again a couple times last week and when I don't hear the beep with LightsFlash, and I do hear the lock/unlock cycle, the other three non-problem doors (and rear hatch) do stay locked. Maybe this was set by the dealer, as you suggested.

Do you have any idea how difficult it is to replace that right-rear actuator? I ask because I've done these actuator replacements on a couple other vehicles, and they can be really easy, or almost impossible.

Regards . . .