If it's a P38, the tail gate release motor/button gets it's power from a micro switch in the drivers door lock, so if the button is OK, the odds are that the problem is there. If only the nearside rear light has stopped working it could be a bad earth.
Thank you for reply.
Drivers door lock was replaced recently so should be ok. Yes is a P38 2000 4,6 sorry
could bad earth affect both light and tailgate?
The wires can break where they flex going into the lower boot section.Thanks for reply
Getting continuity through the switch.
Have found a post from earlier saying to check the connector from the drivers door so going to check that tomorrow