My coach has individual relays for each bright half of bulb , brake, emergency, right and left. Most every issue I've had was connection to relay from spade. I think I may have had to changed one relay. Mine is built old school ,wires to these relays not plugs but same idea though.
Some owners have issues, root cause by trailer plug/wiring .
95 Monaco Crown Royale
M11 400hp, 4060 trans.
Aquahot, Generac Guardian7.5k