"Which" lamps are we talking about?
Illumination? This is a "trick" circuit
The headlight switch receives power from TWO sources. The one we need is from the tail lamp fuse, powers the tail, park, and illumination (dimmer controlled lamps.
From the light switch, power goes through the dimmer control, so it must be twisted to the left (bright). Power then LEAVES the dimmer control and travels (tan wire) to the small instrument fuse which is normally at one end of the fuse panel
Through that fuse, then out to all the dimmer controlled lamps on oragne wiring.
So turn on the park lights and take your meter/ test lamp. Turn the dimmer control all the way to the left, check that the park/ tail lamps work.
Now take your meter / lamp and find the inst. (instrument) fuse. You should have power on both ends of that lamp.
YOU WILL NOT have power on that lamp if......
The tail power circuit is bad feeding to the light switch
The tail fuse is bad
something wrong in the headlight switch
the dimmer control is bad or twisted to the right (dim)
or the light switch is "OFF"
