i have a 89 w150 and got in her today and the high beam on one side works but not low beam and on the other side the low works but not high. whats the deal? i replaced the battery yesterday in it. i know they worked the night before.

 

did you test the lights individually to make sure that high and low beam on each light are good?

 

i sure did and they are good.

 

could it be the headlight switch?

 

Not the switch. Did you possibly move any of wiring while installing the battery?

 

when in doubt keep shaking wires till you see sparks or till they start working. there is no chance it is the switch.

 

i dont recall moving any wiring

 

you could have nudged your headlight wires since they are right there by the battery.