Caravan lights

[graham hall]

Just bought touring van ,one brake light staying on other not on at all. New tow bar fitted. Any help appreciated.

 

[Burnerman]

Caravan plugs and sockets are notoriously poor quality.....have a look at the terminals ( you may see the copper turning black) and particularly the earth connections within.
Also incorrectly fitted bulbs will give all sorts of red herrings - especially twin terminal stop/ tail fittings.
Consider converting to LED fittings if you don’t already have them!
John

 

[foxhole]

Brake light switch likely broken, constantly on may just have blown the other brake light or melted the fitting if it got too hot.