Laserline 291 Alarm problem

[N7GTX]

The car sits perfectly ok with the alarm activated for a week or more. Then after a Sunday drive and parked up, I set the alarm with the fob. 2 beeps and hazards flash twice so all armed.
At 4am the alarm goes off. Press unlock then lock and it goes back to sleep like me. It will stay this way with no issues indefinitely.
Using the self diagnostic function by pressing both buttons together it says, "the ultrasonic sensor generated an alarm condition."
So I check the CCTV and there are no cats, dogs or birds to be seen. The strange bit is that it is always around 4am that this happens. And ONLY after the car has been driven that day. If I just open the doors it does not happen.
The main problem is I cannot find the ultrasonic sensor. Does anyone know where it might be located?

[chimp427]

Ultrasonic sensors are usually mounted on the screen pillars etc and are visible as they detect air movement, you normally see microwave type sensors on soft tops as these pick up body type movements.
Maybe someone has tucked the ultrasonic sensors away somewhere or not fitted them at all?

[N7GTX]

Yes this is my thinking too. Checked all around the pillars/mirror/sun visors but no luck.

However, after PROPERLY reading the instruction manual I can, apparently, lock the car with the usual button (of the 3) on the fob, then within 30 seconds press the panic button once and this disables the ultrasonic sensor. Think this is a feature for when you leave the car with the top down.
So I will give this a go and see what happens. It is a once only feature so each time I lock the car I will have to remember to press the second button.

[chimp427]

Id probably try to find the brain in this instance and try and trace any wiring from it, i cant remember if there is a sensitivity setting on it for the sensors.

[Sardonicus]

Should be fitted with a microwave sensor you dont generally use ultra sonic sensing on a convertible maybe the diagnostic report is generalizing interior sensing ultra-sonic/Microwave movement

[N7GTX]

chimp427 said:

Id probably try to find the brain in this instance and try and trace any wiring from it, i cant remember if there is a sensitivity setting on it for the sensors.

I know where the brain is so I might just have a look and see if anything is adjustable.

[N7GTX]

Sardonicus said:

Should be fitted with a microwave sensor you dont generally use ultra sonic sensing on a convertible maybe the diagnostic report is generalizing interior sensing ultra-sonic/Microwave movement

Yes, just the terminology in the booklet. Still cannot find anything that resembles this though

[Sardonicus]

N7GTX said:

Yes, just the terminology in the booklet. Still cannot find anything that resembles this though

Yhm

[N7GTX]

[N7GTX]

Well after taking various bits of interior out today, I have located the immobiliser and also (with Sardonicus' help) the central locking control unit. No sign of any sensors - microwave or ultrasonic so for now I will assume they are not fitted and use the bypass sequence on the fob. Thanks.