BREAK LIGHT WIRING

I recently got this truck, looking at the trailer light connections were a eye sore. Obviously who ever hooked them up didn't have a clue what they were doing. So I cut the plugs off along with the switch under my steering wheel. On the way home one night a guy yells at me and tells me only my third break light is working. So when I get home I get my meter and head under the truck to find a four white harness for the light I disconnect and press the breaks to check for power. Nothing on any of the four. I peel the plastic back that was covering the wires to find a white wire tucked up in there. So I test it and come to find out it's the wire that gets power when I apply the break. I sliced it into my turn signals and thought everything would be good. Now the problem is if I have my turn signal on and hit the breaks it makes a buzzing noise in the cab so I know somethings not right. I've been going around with this for months. Someone please say you have had the same problem and help me with the fix!!