Headlight dim on right side

[Bikejz]

I have a 97 LC 80, lately the right headlights are dim ,when the truck turns on. I can flick the passing lights and both lights will light up evenly. Is this the switch or something else?

 

[new96FJ80]

I have a 97 LC 80, lately the right headlights are dim ,when the truck turns on. I can flick the passing lights and both lights will light up evenly. Is this the switch or something else?

Same issue, except driver side low beams are dim. Have been for years and new bulbs don't change the output. Lens is clean, so maybe grounding? Have you found an answer?

 

[jonheld]

All 4 bulbs are fed from a single +12 source, however each low beam is grounded separately. Each one to the corresponding inner fender.