When I turn on the ignition my rear passenger cabin light comes on and I cannot turn it off until I lock the car.  Any suggestions as to the cause ( short circuit or something?).

Check the light switch hasn't been turned on - especially if you have "little" people in the back.

 

The light will go out when you lock the car as it shuts down all sorts of things, but will come when you unlock and stay on with the ignition. There's a few posts about this across all models.

Edited 12 February, 20233 yr by geordiebloke
Didn't make sense

I have checked all the switches and as I don't have kids it's unlikely anyone has been tampering with them.

Have you checked the switch in the front of the car as well as in the rear?

Yes I have. That's why I don't understand it. The light only goes off when I lock the car.