Freelander 1 Td4 electrical mysteries

Hello,
My plucky little Freelander is starting to fray around the edges at 194000 miles...
Recently, a few seemingly unconnected electrical systems have been intermittent together (and have now stopped being intermittent and have just stopped working altogether). The systems are -
Front windows
Rear door latch
Radio
Interior lights
'You’ve left the lights on' warning beep
They all went at the same time - which suggests the CCU is at fault. But some other CCU functions are working fine which suggests it is not the earth connection. All fuses and relays are fine and I swopped fusible links 3 and 4, which had no effect.
Any suggestions please? Are 2nd hand or recon CCUs a viable option?
Many thanks,
Roy

First thing I would try would be to disconnect the battery for five minutes and see if that clears any of the faults. Make sure you have a radio security code, if your radio needs one.

Does sound like a CCU issue. It might be worth checking if the screen is leaking, which can drip water on to the back of the CCU.

Thanks folks,
Disconnecting the battery didn’t help :/
It doesn’t leak but the screen does take ages to clear if it mists over - I’ve always put that down to the fan being a little half-hearted - perhaps it drips some onto the CCU.
Does the CCU suffer if it gets wet other than the earth connection? Not that I have had problems with it before but I would be surprised if some of the functions stopped working whilst others continued to work.
Has anybody ever bought a 2nd hand CCU? (Money is tight and I don’t want to throw away £20 on something that doesn’t have a decent chance of working).
Thank you,
Roy

CCU has come out so I could check the numbers - 2nd hand unit arriving from ebay on Wednesday.
Hoping there won’t be a key compatibility issue or any immobiliser surprises...
Roy

Fobs need recoding to ccu and you need to check the 3 or 5 door is correct else it will look for a hardtop and if you have a 5 door you won't have one!!
Radio feed doesn't come from ccu so that is the odd one out.

Incidentally, ccu showed no signs of ever having been wet.

Thanks Andy,
Will make sure ordered spare is 3 door.
Roy

Dunno where you are, but I can code fobs if it solves problem. North Devon, S Molton.

So just as replacement ccu arrived, the intermittent fault cleared - first clue was the radio coming to life and then all the other functions worked for a few hours.
Replaced the ccu (it isn’t hard to do without taking out the fuse box, despite what the online manual says) and it worked, then the fault recurred and has remained non-functional since. I don’t think there is anything wrong with my ccu so I am going to send the new one back.
So am trawling through wiring diagrams trying to find a common thread for these functions...
Thanks,
Roy

Did the ccu change bring back the problem?

If so I'd be checking ground leads in that area.
As well as common feeds that you are looking for, check Rave circuits and see if there is a common ground for the affected circuits.

Been looking at circuits. FL4 looks like a common potential problem but you have substituted that.

Why not, if the fault is now on, take a simple failed item, like the radio and check it back via the circuit to find out where the feed disappears. This may reveal the other issues too.