To lock your car while disabling the motion detection system, follow these instructions:
Quote:
Switching off towaway protection and
interior motion sensor
Deactivate the towaway protection and the
interior motion sensor when locking the vehi
cle and
• transporting the vehicle,
• board, e.g. a ferry or auto train,
• there are people or animals in the vehicle,
• the side windows remain open.
This prevents any false alarm.
The switch is located in the upper center
console.

1 Towaway protection/interior motion sen
sor switch
2 Indicator lamp
> Remove the key from the starter switch.
> Press switch 1 within 60 seconds.
Indicator lamp 2 comes on.
> Exit the vehicle.
> Lock the vehicle using the remote control.
[i] The towaway protection and the interior
motion sensor remain switched off until you
lock your vehicle again.
|
Owner's Manual pages 78-79
Hope that helps your neighbor and your sanity... at least for the time being!
As for a probable cause, it could be, as you said, a faulty connection, or, as it happened in the past, an upside down sensor. There are two sensors, one in the gearshift housing, and one under the car aimed at the ground. You may try to get in touch with your dealer to try to have it diagnosed over the phone.
Good luck.
