Voltage problem

Trying to keep from starting from scratch, okay here my problem

I have one taillight brighter than the other and the reverse problem with the brake and turn, I've replace sockets and light bulb to the same results

The driver Side has the low voltage to the taillight bulb but good voltage to the turn and brake light

The passenger side has great power to the taillight but low voltage to the turn and brake light...note it looks like someone has spliced the wires to the passenger side...if they reversed them could this be my problem causing problem on both sides???