I had similar issue when we got a Disco 5. Caravan is a Swift Challenger which has led lights. Solution was a lighting module (circuit board) which needed to be installed. I purchased this from Sargent electrics. Simple to install and lights worked fine once in place. The Sargent web site does provide some explanations.
Recently got rid of the Disco, most luxurious expensive piece of junk I have ever wasted money on, and replaced with a Q5 which needed the lighting module removed for the caravan lights to work.
Links to Sargent is https://sargentltd.co.uk/
For info, I have no connection with them but when really helpful so may be worth a call.
Hope this is helpful
Pete
