Thanks for the comments on this. I have tried holding the remote up to the diversity module and the key works every time when within a foot or so from it. I guess it has lost ability to transmit any further than this, so I will try to get a replacement unit.
A couple of people have mentioned the radio when referencing this unit, is this unit also the radio receiver? My radio works fine, but I have noticed that when using the rear screen heater, the radio reception is affected and I can see that the screen heater is also plugged into the unit.
Presuming the unit has been affected by water, I have looked for signs of this but can't see any problems, drainage routes seem to be channels rather than pipes or ducts that could have been blocked, I have left the trim off for now and will have a look the next time the car gets wet, or I will try a bucket of water if it doesn't rain soon, typical living in England in the Spring and we are not getting any rain, that never happens!

Hi Mark some of the ribbon wire embedded in the glass are the AM FM antenna, that's why the wires are connected to the diversity antenna module. Same for the rear back window, they are antenna too. Once you change the DA module you should be fine

Thanks for your comments on this, it has been a help.
Sorry for the above post not being too relevant to the thread it was supposed to be posted in my own thread, I will go paste it there too!

Have you checked your fuses?

Like THIB mentioned in his reply...the aerial antenna for the remote key is embedded in the rear left cargo area window. See the image below for the location of the FZV (central locking system) aerial antenna that you'll find in the Tourings and SAVs (not in the rear window but the side cargo window on the rear left):





There is a module that the wiring connects to before it gets to the diversity antenna/amp that was previously pictured. (see pic below for location of the back-up antenna and the hardware that secures it to the body of the car...make sure those connections are secure and not corroded)

• Release screws (1).
• Remove back-up antenna (2) and disconnect associated plug connection.

Hi, i checked the fuses before (all in related to the central locking system, marked with red arrow in attached photo). I'm wondering if these are the correct fuses to check?

Yep. They’re the ones.

You may see a thread I started because I couldn’t lock my car with the remote. Had to use the little metal key.

It was a fuse. Unfortunately I did not note which one. But a burnt fuse is obvious.

Good luck.

Thanks, I checked all the fuses mentioned in the 'central locking system' again, this time using the multi-meter. (both in trunk and under glove box). All fuses are good, so my problem is either with the diversity antenna or something is going on with the key fob not syncing with the CAS. Will update the post over this weekend once I try to swap the diversity antenna from a working vehicle. Thanks for all the suggestions.

Hey Thib, if I remove the diversity antenna from a working vehicle,(to test out in my car) will it need to be re-programmed once I place it back in the original (donor) vehicle? Does the battery need to be disconnected during the removal? Or is it just a 'plug&play' with no need to re-program or battery disconnect? Thanks!

UPDATE:

Installed a working diversity antenna, no change. Key fob not working at all. So that eliminates the diversity antenna as the culprit.

Does anybody know the steps for pairing the key fob to connect with the car? I've read on another forum that to pair: put the key in, start engine, stop engine, take out key and press lock on the fob . I tried and it doesn't work either.

Also, anybody know of the software that can be used to test the key/CAS?

Thanks!