I've got an LS400 mk4, and I've got a strange issue with my alarm.

Normally, when I press the lock button on the key once, the car locks and the indicators flash once. When I press it a second time, the locks sound as if the activate again and the indicators flash five times. I believe this shows the deadlocks and internal sensors have been deactivated.

Now, pressing once gives the one flash, but pressing twice gives no flashes at alll. The alarm still seems to work as it goes off when I unlock the door with the key, but if I sit in the car and lock it, I can't get the internal sensors to set the alarm off ( picture someone sitting in a locked car frantically waving their arms about... ).

Any ideas

KEITH

Hi

I thought on the second press it ACTIVATED the double locking. If you want the interior sensors off there is a switch inside the car... anyway sounds like a fault with the double locking, I'd check all the door locks work on their own...

Try sitting in the car, press the button once and see if you can open the door from the inside, this will show if it is double locked...

Hopefully someone will have a hand book for your car and help you out...

You could also look through the fuses to see if any are blown... that should take a few hours...........

Good Luck

Pete

I've just looked at my handbook and it makes no mention of pressing the button more than once.
I'll try mine in the morning (complete with waving arms ),and let you know.

I've just tried mine.

Sitting inside one press locked the car, WAITED until the security light on the dash started to flash then moved. My alarm sounded before I had time to get my hand to the door handle, so the movement sensor works. When testing you have to wait for the system to arm which is when the dahboard light starts to flash. If you don't then nothing happens even after you have opened the door.

I also tried pressing the button twice and the indicators flashed five times and the locks clicked. Again waited for the security light to flash(30 seconds) then waved my arms about but nothing happened until I opened the door when the alarm went off. So it seems the extra push on the button turns off the sensor.

I've had another look in my hand book and still can't see any reference to pushing the lock button twice.
Just noticed in the book it tells you to open the windows before testing the alarm I'll try that later and let you know if it makes any difference.

Thanks for trying all that, it's pretty much what I expected should happen.

I decided to have a quick look at the fuses in the engine bay and the one marked OBD looked as if it might be dodgy so I took it out to take a closer look. The siren alarm went off. Odd, I thought, so I tried it again. The siren alarm went off. Very odd.

I remember reading that if you disconnected the battery for about half an hour, it tended to reset everything, so I did that. The siren alarm went off and kept going off. So, I reconnected the battery and now the indicators flash 5 times. The deadlocks and internal sensors are still not working though.

I think what's happened is that the dealer disconnected the battery when they replaced the cambelt a week or so ago, and the alarm came back on in some kind weird state and needs a full reset to clear it. I'm assuming the siren has it's own battery, or at least a temporary power supply which allows it to sound when the battery has been disconnected. So, does anyone know whether the whole system will reset if I disconnect the battery for a while, or do I need to do something else?

I think I've annoyed the neighbours enough for today, so I'll try again at the weekend.