Im of the believer that using your pinky is ALL about the position of the left thumb, make sure your left thumb is about the center of the back of the fretboard and your fingers are perpendicular to the fretboard, if your thumb is doing like the jimi hendrix things, you cant reach with your pink as well nor will it be as strong. keeping your wrist relaxed and in a comfortable position is a must. The reason why your pinky is weak is because how you approach holding the neck and how the angle of your wrist affects the abilities of the tendons of your hand and forearm
Also, in upright bass technique we use a 1-2-4 fingering system which i find is the best way to approach an electric bass for the most part, using the ring finger is usefull but for the most part, your pinky is the better choice other then like full on chromatic runs or whichever scale patterns. For example tho, il use my pointer to pinky for most fretting until i get to the 12th fret mark, and although this may not be the best, i do this on guitar to :S