Turns over but won't start no dome headlites or horn or int and instrument lites

Check all wires going to battery for corrosion. remove cables and clean connections, other problem could be at the starter. Get under the vehicle and check that all wires have a good connection and not broke/corroded.

www.yardtruck.com/documents/4x2-6x4-maintenance-manual.pdf

use scanner to read codes

With no other info, make/model/year etc... My guess would be that it's a battery saver feature that the manufacturer of your vehicle chose to implement.

Press the dome light switch four times, the chime will ring and the lights will turn off. Repeat to turn back on, Will default back to on next time you start vehicle.
DaveP in Ohio

mcdevito75 here, It could be the dimmer section of the headlite switch, when dark outside put head lites on and see if you can turn the head lite switch either to the left or right to get the instrument panel lights on. Turning the headlites on and off could have turned the switch enough to keep the instrument lites from comming on, specially if your not the only driver.

Blown fuse check manual.

Check to see if the wiring isnt wrong. sometimes wires get crossed and the lights wont function properly. check each strand that they go where they belong.

horn and dome on same circuit,i would check dome wire under carpet

some times there is an aditional swich to get the light down look very well but if not these systems are very complicate they have a lot of relays i will recomend you to take it to an auto electrical facility