custom90 wrote:

Probably the rear lighting loom ground stud loose and the associated ground eyes, it’s on the side of the transmission.

It’s a common fault as it’s common ground in my opinion, switching on the hazard switch, is a higher load as it switches more circuits, so the higher current draw, overcomes the high resistance, due to the loose ground.

Not guaranteed but that’s my guess.

If it does happen to be the issue, use a little low strength loctite like 222 if you have any, just a very small amount.
As it can come loose, as it’s subject to very high vibration and harsh conditions.

There is no guarantee it is that, but hopefully a high likelyhood.