My 96 sonomas tail lights won't work with the headlights on,but the brake lights do.also my turn signal on the drivers rear works but the passenger rear when used makes the left one come on in a "hazzard"style. I also have no backup lights.I have replaced all bulbs and don't know what else to try. Thanks for the helpp in advance

. Test all under dash and under hood fuses with a test light or multimeter:

https://www.askmehelpdesk.com/cars-t...tml#post252145

. Check/replace multi-function switch.

Where under the hood would they be? I've checked all the ones I could find and the ones under the dash . All good? Light switch problem maybe?

Where under the hood would they be? I've checked all the ones I could find and the ones under the dash . All are good . Light switch problem maybe?

Every car and truck has two fuse boxes. Follow the cables from the battery. Make sure you use a test light or multimeter and check for "power through the fuse." Visual inspections are "unsat." Be very thorough, since it will save a lot of time and money.

Thanks guess I better charge my flashlight now!

Yes. Be very thorough.

At the rear of the vehicle, with a non-powered test light connected to a good clean ground point, check the tail light harness and sockets for power at the proper time: brake, turn, back-up.. These tail lamp 'plates' have been known to fail open, not allowing power to reach the bulbs.
While in there, a close visual inspection of the socket terminals is in order. If the terminal tabs are corroded or damaged, replace both of the plates. Install new bulbs, but not the bulbs with plastic bases. It has been my experience that these bulbs fail far more frequently than glass-based bulbs.

Can't say for sure on this vehicle, but many have the signals from the signal head(signal switch), tail light from the head light switch and the backup from a transmission switch, may not apply here, but would test for a bad ground.
Try connecting a wire from the battery ground or a good body ground and jump to the ground of 1 of the sockets.
Any Trailer wiring?