Rear light going off when brake light comes on

[WSB]

My Zafira rear lights work fine. My rear brake lights work fine with rear lights off.
But if I brake with rear lights on, on one side, no lights come on at all.
I have changed the bulb but that has made no difference.
Any ideas?
Dodgy connection?

 

[Burnerman]

A dodgy earth connection in the lamp cluster, more than likely.....assuming the correct bulbs have been fitted!
John

 

[WSB]

Thanks, pretty sure the bulbs are correct, as the problem only started occurring recently with the same bulb. Cluster looked ok at first inspection. Will give it a good going over and clean up over the weekend.

 

[Tech_Man]

It could be a broken wire in the loom. Vauxhalls are notorious for snapping wires at any point that has a pivot and a wire runs through. Its notmally around the hinge area and you will see a black gromit between car body and tailgate. However to inspect you need to move the gromit away which can be hard. I would check the cluster first