Freelander 1 Parking Aid or Reverse sensors

Hello all, I wonder if anyone can help.
The reverse sensors on my td4 hse aren't working. The flashing light on the switch is working but no sound.
The fuse is ok
Thanks.

It could be lots of things, but the speaker is known to fail, as is the control unit, actually the sensors fail too, but no sound at all is normally the speaker.

If you turn the ignition on (don't start the engine though), put it in reverse and listen real close to each sensor you should hear a rapid high pitch clicking noise from each sensor if they are all working. You need the background noise to be quite low (or have the hearing of a pre-teen or bat) as it's difficult to hear but if they are all working you should hear the click.

But I think Nodge has got it right and its the speaker or parking ECU. I currently have a u/s sensor (reversed into a wall - how ironic to break something that was designed to prevent me from breaking it in the first place) and the control button flashes and gives me a long (5-10 secs) beep to tell me there is a fault.

Fritz