Helpermunk

Just bought a 1997 LS400 last night. As I am about to drive away the (private) seller tells me that the batteries in both remotes are dead and need to be replaced. I drove straight to Walmart to buy batteries and installed them in while still in Walmart. As I am coming out of the store and still quite a distance from the car I hit the lock button and I heard a beep and saw the headlights flash. When I got to the car I pushed the unlock button and nothing happened. I unlocked it with the key and got in. I tried the trunk button and it unlocked the trunk. The remotes work from quite a distance to lock the doors and unlock the trunk. Both remotes are doing the same thing. They both Lock the car and they both unlock the trunk but when I press the unlock button for the doors nothing happens with either remote. No beep, no lights no sounds from the locking mechanism in the doors, nothing.

I have read threads where people say theirs lock the doors but will not unlock the doors but they also say that theirs does not unlock the trunk. Also in those threads even though the problem is slightly different I have yet to see where anyone has resolved their issue.

I have tried reprograming the remotes and the issue remains unchanged.

Contacted the seller who said he did not use the remotes very often, he preferred using the key to lock and unlock, that is why he did not replace the batteries when they wore out, however, he "thinks" all the functions worked the last time he did use the remotes.

Any help or suggestions?

Thank you

CLLEXUSS

Well it's interesting that there is no sound at all when u try to unlock, it's silent.
If you look it up you get things like a fuse, or a power door lock switch, or a power door lock actuator are the most common things but I don't know if it's any one of these things.

Helpermunk

Thanks CLLEXUSS. I am going to check all the fuses tomorrow and I would love for it to turn out to be that simple. I'll let you know how it turns out after I check the fuses.

Yamae

I think that the fuse is OK since the power is supplied for both to lock and unlock by the same fuse.

I worry that the car is in a security function mode which disables only the unlocking. In this mode, you can lock but can't unlock using a remote. This can be checked by a method twisting the key totally 10 times in accordance with the time table. Sorry that I don't remember the detail of it and can't inform you how to do the check precisely.

Helpermunk

All I have been able to find is the following:

Step 1

Turn the ignition key to the "LOCK" position. Remove the key.

Step 2

Close and lock all the doors, the trunk and the hood. Wait about 30 seconds until the security indicator flashes.

Insert the key into the driver or passenger front door. Unlock the door. The turn signals flash twice to indicate that the system has reset.

I have followed this procedure and noting has changed. I am beginning to think perhaps that both of my remotes have bad lock buttons. I am planning to order a new key fob and see if it will allow me to unlock my doors remotely. If so, I will order a second remote to replace both of my bad remotes. If it does not resolve my problem I will likely be right back here asking for more ideas.

Helpermunk

So I remembered reading on another post that the remote locking and unlocking system could be reset by disconnecting the positive battery cable for thirty seconds and then reconnecting it. I was not very hopeful that this would solve my problem but I figured it was worth a try. I did just that earlier today and now both of my remotes are working perfectly, locking and unlocking the doors. Thanks to everyone who responded with helpful input and suggestions.

CLLEXUSS

wow, it was just a little buggy, like re-starting your home computer fixes these buggy little issues sometimes, very interesting

JohnAndic

Glad you could figure it out for now anyways. Great looking car BTW, wish mine was that clean.

hemant

I bought LS400 in 1997. I still use it. Your car looks amazingly beautiful. Enjoy it.
I came to this forum to see what batteries I should use to replace (in my remote). It took 24 years for batteries to dry up. Still works, but only from 10 feet away.

LexUK400

Can I ask - did you first remove the NEGATIVE terminal on the Battery before the Positive?
Removing the Positive alone I would think results in a spark (voltage jump) when re-connecting. (Not good for the ECU??_
I have the same issue the Car won't lock/unlock using the fob but will with the key in the door. Car was unused for fourteen months owing to lockdown and shedding a rear strut when abroad. All good now, but for the Remote lock/unlock. I did leave the negative terminal off the battery for the 14 months.and had the key in the ignition when re-connecting t avoid a Blaring siren, or so I thought. No siren, and able to unlock the boot with key when the Car is "locked" suggesting the Alarm is not working even though the red light does flash.

Yamae

If I were you, I simply remove the terminal again and wait sometime and then connect it again. The purpose for this is to enable to do the power off reset and the power on reset.

Regarding the terminal side, all you need is to stop the supply of electrons and you don't need to worry about. Either will do but for the safety reasons, Toyota recommends to remove the NEGATIVE terminal. Sometimes the waiting time requires several hours or more depending on the amount of stray electrons remaining in the system chip. Anyway try just several minutes first.

LexUK400

Thanks Yamae. Good news is the lock/unlock is now working. Can't say for sure what fixed it. Disconnected live and Neg terminals for ten mins when Remote lock set to OFF. Reconnected and set to ON and tried without success with usual key. Then ten minutes later tried with second key and WORKING!! (I had tried both keys in the past and checked the batteries) Battery of primary key definately 3.18v so should have worked. Issue may be fluff or poor matching surface inside the key. Can't see that it is easy to get into the key or remove the side button. Looks like would have to take out the PCB holder to get to the contact point and it doesn't look like it comes apart.? Probably not a good idea to squirt some electrical cleaner into the spring part. Hey ho will manage with one key, I guess.. Good to get it working again although have to point it closely which has always been the case. RF seems to die gradually.

jhpcat

I know this problem has been addressed one way, and here is another to consider. I called my Lexus mechanic. He only works on Lexus. Thats it. He told me to sit in the car, turn it on, activate the switch on the door panel which locks all doors, then unlock them the same way. (did lock and unlocked twice actually), then try to use the remote to see if it will now lock and unlock. It worked. Amazing. Seems to have reset the remote lock system. Not saying that will work for you, but its worth a try. I have a 99 LS400.

LexUK400

Thanks. Tried above but didn't work for my older '93 key which has the button on the side. Still tempted to squirt a little evaporating cleaner into the push button. Unfortunately the centre immobiliser part of these older keys doesn't just lift out but is welded to the plastic. Perhaps not, as may lose its ability to start the Car. Anyone ever tried to clean an older key? Fluff may be the issue.