in your diagram - E1-18T Instrument Lamp (FEED) feeds the instrument panel fuse in the fuse block. The E2-18O (fused output)goes to the instrument panel lights. Both 18T (top of the fuse) reads 0 volts as does 18O) bottom of the fuse... when using the voltmeter...

My thinking is my dimmer switch is bad... as all other lights, Dome, door jam switches, turn signals and indicators on the dash, H/L headlamps. bright light indicator and map light all work...

From the diagram this implies that the H/L feed to the dimmer switch L7A-18BK is hot - otherwise no dome light etc...

What do you guys think?