Clearance light trouble

Check all the Earth connection. B

Wayne
Is it ALL clearance and both tail lights which are affected? OR only one side?
DO as Barnray suggests and check all earthing points for integrity, however, the lighting for outside should be separate from lighting inside. Is any of it affected or isn't it obvious.
Do you have a breakaway system fitted?
Is the problem ONLY when the onboard charger is topping up the battery. If so, it may be related to the higher voltage applied when the charger is above float voltage. Heaven knows how Jayco has it wired.

If your onboard system charges the breakaway battery, it may have a fault in the trailer plug and feeding to the clearance ( brown wire) somewhere in or near the plug. Check the internal connections of the trailer plug for stray strands of wire or full of conductive dirt which gets wet sometimes and conducts where it shouldn't.

Well we found the problem with the clearance lights
It was the T,V, power cord causing a short when we put the T,V, on the lights would glow after about 10 minutes. new power cord fixed the problem hope it may help someone else