No beep on rear sensor

My E53 X5 2006 Parking sensor seem to have a mind of their own. When I start the light on the P button flashes - but there is no sound. The sound stopped working some time ago when things were working as they should, I think I have identified the fault sensor - however all the threads I have read say theirs beeps - mine doesn't beep so think I have a faulty beeper - anyone know where it is located and whether it is easy to replace

if the green LED is flashing you have a bad wire/sensor

turn ignition on, engine off
press button
go up to each sensor put ur face close to it and listen for a clicking sound
the one that doesnt beep is bad

Thnx - bur I know how to do this, but it has not answered the bit about the lack of beeping...

Can you clarify for us which rear sensor you determined is making the "clicking" sound (share with us it's location...left rear, right rear, 2nd from left rear, etc) it's obviously the one rear sensor that has failed. And when you say there's no more beeping from the rear PDC sound generator (chime/gong/etc)...have you tested the OTHER rear sensors in that there is an obstruction in their field...but the sound generator doesn't beep?

The only way we know what's occurring is by what you tell us (the picture you paint)...and when you leave out details or leave holes in the story...it makes it difficult to give suggestions without repeating what you've already done or ruled out. Help us hlep you better by making sure you give enough details for others to make good suggestions about something they can't see, hear, or know what you've already done.

OK I appear to have confused people. Let me be clear.......

Under normal conditions if everything is working OK I would expect to hear a series of beeps whilst in the cabin as I get closer and closer to an item. These beeps are no longer heard.

All my rear sensors are clicking when the ignition is switched to the on position, the front sensors (either side of the number plate) are not clicking and I will need to replace these.

However I want to know why I cannot hear any beep/tone from the cabin of the car? Will I need to replace the unit which omits the beeps and if so where is it located.

The PDC control module is located by the battery (see the component on the left side in front of the battery in the diagram below). I'm not exactly sure where the rear PDC speaker is located on the e53...but it sounds like it may be coming from the right cargo area. I'd pull the panel and check around the fuse/relay panel to see if there's a speaker back in that area. I know in the sedans, the rear PDC speaker is located under the rear parcel shelf on the right side near the audio system speaker...this probably translates to the right cargo area on the e53 & Tourings (as a guess).

If you find the rear PDC speaker, and it tests to be okay...my next move would be to check the PDC control module.