Trailer brake actuator

I think mine cost around 30 bucks , installed it myself . I presume you're wiring for a round multipin plug with brakes and lights and all that . Pull your "main" power direct from the battery with either a breaker or fuse . You might be lucky enough to have a vehicle new enough to have built-in wiring for that ...

I installed mine myself, many good brands to choose from. Mine is called "Journey HD".

Look for one at about $100. You should have one that has an inertia sensitive chip and will work in reverse as well as forward. It's nice to have brake control in reverse.