Ls400 1998 Remote Alarm Problem ?

[bazgtr]

Right got a problem with the LS400 1998 model.

Leave the car overnight and the remote stops working in the morning and the alarm light is on in the car. Got to open door with key, Alarm goes off and then have to use key in igntion to stop alarm.

Once I've got to where I've got to the remote works perfectly everytime allowing me to open close open close time after time with the remote. Once I leave it overnight the remote stops working and back in the same boat.

So don't know if this is a cold hot thing as the remote works when the car engine is hot or because it's getting a charge from the alternator which allows me to use the remote correctly just after stopping.

Have charged the Battery and it's shooting out around 12.7 Volts on the meter. Is that correct for a 1998 model???

Have planned to try the Battery from my other LS to see if that's better.

Have see quite a few threads about this but nobody has come back with the answer or fix they used.

Any ideas?

Baz.

[ambermarine]

Hi

Try checking the voltage in your keyfob Battery ,ascertain what it is then put a new Battery in .

The transmitter needs a certain voltage to transmit a signal to the reciever in the car and this can become erratic when the voltage drops below a certain level.You are correct that hot and cold do have a effect on the voltage as a rise in temprature will had a little more life to any Battery for a short time.

[bazgtr]

Hi

Try checking the voltage in your keyfob battery ,ascertain what it is then put a new battery in .

The transmitter needs a certain voltage to transmit a signal to the reciever in the car and this can become erratic when the voltage drops below a certain level.You are correct that hot and cold do have a effect on the voltage as a rise in temprature will had a little more life to any battery for a short time.

Update on this.

Put new battery(£126) in car as the one in the car was not upto much and not the spec for the car. Now got full power the stereo sounds much better but didn't fix the problem.

Anyway had a look at the keyfod inside and there is a small crack on the transponder part so didn't go any further in changing the fob Battery incase it fell apart on opening.

Got new key(£115) coming from Lexus to finally to see if it was the remote.

Hopefully that will sort it out and it was the key fob.

Also did buy one of those transponder remotes on eBay that can be programmed to the car along as you have a master key with you.

So does anybody know how to program to the car as didn't get the instructions with the parcel and seller not got back to me yet and want to try tonight.

Anyone Know?

Baz.

[steve2006]

May not be the same but have a look at this link

http://us.lexusownersclub.com/forums/index.php?showtopic=26715

[bazgtr]

May not be the same but have a look at this link

http://us.lexusownersclub.com/forums/index.php?showtopic=26715

Here's an update on this problem

Had new key cut from lexus coventry too which fitted all the locks but needed to be programmed in at Lexus Cardiff for the security system to alow to start the car.

Went down and they manged to get the key to start but were unable toto get the central locking wi fi system too work as they state they are unable to connect with the car for the key to be programmed in.

Anybody else had that problem in the past?????????? No communication?

Anyway I was happy the new key started the car and went about changing the Battery in the old remote to see if that was the problem in the first place. Changed the Battery and since then the car opens and shuts like it's designed to even in the mornings as when the problem shows up.

Have now swapped over the transponders so I have one fully working key but still need to get the other new transponder coded to the car.

I need to check out why the car doesn't communicate.

So will investagate further.

I might just buy the coding Toyota/Lexus unit box for £180 and do it myself.

Baz.

[iamthestig]

Hi Baz, I have the exact same problem as your original post with my 99 LS400. The fob won't open the car after the car has cooled down. If I go for a drive I can open and close with the remote over and over again. If I leave the car for an hour or more it won't, although sometimes if I keep trying for a few minutes moving the fob around the car it might work.

I changed the fob Battery a few months ago, before this problem arose. I did have to trickle charge the car Battery when we had that cold spell last month, but the car starts very easily now. Was your solution to change the fob Battery and has that rectified it permanently?

Thanks,

John

[iamthestig]

Just to let others know I fixed my problem by changing the fob Battery despite it being less than 6 months old and showing a full 3v on the meter.