Check your fuses. The cars book should tell you where the fuse box is, and which fuse is for your parking lights.
Make sure parking/tail lights are working - if not, may be a fuse If parking/tail are working - may be bulbs or switch
If parking lights and dash lights are not working and fuse blows out, there might be a problem with battery corrosion. Check the components specific to the circuits of the affected lights. It might be loose.
Check to see if the parking lights and tailights are working - if not may be a fuse (same circuit)
If parking and tailights are working could be headlight switch--rheostat for dimming control could be bad
Start small. Check your fuses.
Turn your indicator switch to left/right and the parking light will come on for that side.
If headlamps are not working but the parking lights are working can it be the fuse that is faulty
The GMC dash tail and parking lights are on a different fuse from the brake lights. Check the fuses for a possible blown fuse.
Check the radio/Acc fuse...
If the parking/tailight fuse is good - then it may be a bad headlight switch No tail lights but the bulbs are working? Please explain.
Bulbs may be burnt out.
If you dash lights are not working check that your parking/brake lights are working also check fuses for cig lighter and interior lights that may help get the dash light working again.