You may find that your trailer brake lights are dimmer then normal. Double check to be sure they are coming on as bright as they should. One other issue may be your alternator. Your adding more usage of vehicle electricity output and if your running a stock alternator with maybe 45 amps, it may drop your night time lighting and strain your system causing older alternators to give up. Running LED probably could fix this, but to replace an entire system with LED can get pricey and require a possible transformer to power them correctly.If you don't have a high amperage alternator, it may be a good idea to install one so you have sufficient electrical power, especially at stop lights when it really puts a strain on the system with extra lights being lit up. Bright lights also include more strain.