my s4 TII has a dim driverside head light, bulb is fine, high beam on driver side doesn't work at all.... all started when i grounded my e fam to my headlight cover {hehe} have it moved to chassis ground but am not sure what needs to be replaced... motor actuation is fine btw...

 

Have you tried replacing the bulb? Maybe check to make sure you are getting 12 volts from the power wire when the headlight is on.

 

i would replace the bulb and check for power