[desertmike1]

Mannysalv,
I have a 99/01 CHILTON manual!
Here is a simple brake down on how your headlamps work, starting with the B+ and working our way to B- (battery + & - voltage)

(a) B+ begins at a relay under the hood and is energized by either the (ambient light sensor) or the (headlamp and dimmer switch)

(b) The relay supplies power for both the High and low beams Via a left and right 15A fuse through "A" single wire.

sense your high beams work you can discount, both a & b above.

(c) left and right headlamp low beams have a single "-" negative ground wire (Yellow) all the way to your (Dimmer switch).

(d) left and right headlamp high beams have a single "-" negative ground wire (purple) all the way to your (Dimmer switch).

sense your high beams work you can discount (d) but (c) is a possibility.

(e) once the wires reach the dimmer switch, you will select what ground (high) or (low) beam you want to use.

(f) the dimmer switch has a common ground (black) for all the above functions.

sense your high beams work you can discount (f) but (e) is a possibility.

To finalize, I think you either have a bad wire or connector between the dimmer switch and headlamps, or a bad switch it-self

good luck

-Mike