2013 Saloon rear light unit issue.

Afternoon.

Have been recieving an intermittent fault on my dash showing that there’s a fault on the rear left turn signal. Once the fault appears it causes the indicator light on the dash and ‘tick tock’ noise to go much quicker. However all turn signals are working and are at normal pace when viewing from outside the car.

Once this fault has established, generally if I select reverse, I then get a further fault showing the rear left reverse light has failed, although again, it’s working fine.

I have replaced the rear left reverse light (just incase) and also checked that the rear fog light is working. These are the only bulbs within the inner section of the left rear light as the rest are all LED’s. All other led lights and signals seem to work as intended.

Sometimes the fault will show every day and other times it can go several days without popping up.

Car is at 66k so is low mileage for age.

Can anyone advise on what else I can try? I just don’t have a lot to go on when all bulbs are working when the fault comes up. Connectors on bulb module look good with no corrosion present.

Thanks

I have investigated further and problem is still intermittent. I picked up a 2015 rear taillight from eBay in good condition and after replacing, I’m receiving the same fault. It’s generally after opening or closing the boot, so I do think it’s the wiring within the hinge.
There’s mention of a retrofit guide for rear parking sensors that has a very detailed guide showing the trim parts in the boot that need to be removed to expose and check this wiring but the links have been removed. Does anyone have a link or can point me in the right direction, preferably with pictures?
Thanks

Have taken the boot trim out and exposed the wiring harness clipped to the left hinge. I’ve found a split in two wires and one of the brown wires is snapped, so seem to have found the fault. Can anyone confirm what the AWG gauge is for the wires and therefore what colour butt connector to use to repair?
Thanks