When I turn ON the headlights dash lights go off turn signal indicator lights glow on and high beam indicator lights but high beams are not on and when un conecting seat belt get a faint buzzer sound

Ive changed the relay and the headlight switch on the dash .. still wont turn off headlights ? Just changing parts won't fix it , need to test . Hooking up a professional scan tool , one that can read codes in the BCM - body control module is the way to start to find the problem . Then familiarize yourself with how they work.

Headlamps
Major components of this system are the body control module (BCM), headlamp relay, beam select relay, ambient light sensor, headlamp and panel dimmer switch, turn signal/multifunction switch, park brake switch, and the low and high beam headlamps.
The headlamps may be turned ON in 2 different ways. First, when the driver places the headlamp switch in the ON position, normal operation occurs. Second, when the headlamp switch is placed in the AUTO position, automatic lamp control (ALC) operation occurs. During ALC control, the headlamps will be OFF in daylight conditions or in low/high beam operation in low light conditions.
The headlamp relay receives battery positive voltage directly from the battery. The BCM supplies a ground signal to the headlamp relay for normal headlight operation. The BCM also supplies voltage to the beam select relay coil for high beam headlight operation. When the driver places the headlamp switch in the ON position and the dimmer switch is in the low beam position, the headlamp relay supplies current flow through the left and right low beam headlamp fuses to both low and high beam headlamps. Both low beam headlights are grounded through the beam select relay. When activated, the dimmer switch sends a ground signal to the BCM in the high beam position and a momentary ground signal in the flash-to-pass (FTP) position from G106. The BCM then energizes the beam select relay which switches the headlamp grounds from the low beam headlight bulbs to the high beam headlight bulbs illuminating the high beam headlights. With the headlights in the low beam position, the high beams may be momentarily turned ON or flashed by activating the FTP portion of the switch.
The instrument panel cluster (IPC) illuminates the high beam indicator when the BCM detects that the high beams are requested. The IPC receives a class 2 message from the BCM requesting illumination.
The Headlamps On at Exit and Perimeter Lighting modes can be adjusted using the steering wheel controls to select the function as displayed in the driver information center (DIC). The Headlamps On at Exit selection will allow the driver to customize the period of time that the headlamps remain illuminated upon exiting the vehicle. This period can be adjusted from 0-180 seconds. The Perimeter Lighting feature allows the driver to select if they want the headlamps and backup lamps to illuminate when the door UNLOCK button on the key fob is activated. This feature can be turned ON or OFF by using the DIC steering wheel control buttons.

DTC B2575 Headlamp Control Circuit

Circuit Description
When the body control module (BCM) senses a request for headlamp or daytime running lamp (DRL) illumination, the BCM sends a ground signal to the headlamp relay through the low beam headlamp relay control circuit. The headlamp relay will illuminate the low beam headlamps.

Install a scan tool.
Turn ON the ignition, with the engine OFF.
With a scan tool, command the headlamps ON and OFF.
Does the headlamp relay turn ON and OFF with each command?

Do you know what bi-directional control means ? Need a professional scan tool to do these type of test .

DTC B2602: Daytime Running Lamp Control Circuit Low or Open
DTC B2603: Daytime Running Lamp Control Circuit High

Without this type of info. from service repair manual an using a scan tool your missing the big picture .

The usual cause is a bad ground.
Check the ground with a test lamp.

It sounds like you are confused about how your headlamp system is supposed to work. The DRL does not run on the High beam circuit, it runs on the low beam circuit. The fog lamps are supposed operate with the park lamps and also with the low beams, not the high beams. From your description, I would say that your system is operating as designed and you are having trouble telling High from Low. (Don't feel bad, that is why high beam indicators were invented in the first place.)

PROBLEM COULD BE A FAULTY TURN SIGNAL COMBINATION SWITCH.

take a look at the dash ground wire located next to the right of ebrake release handle. if the bole holding the ground wire is loose, which was quite common it will cause all kinds of feed back problems, like described in the comments section to your question.

You need a new headlight dimmer switch located on the steering column between the dash and the firewall

Sounds like a bad switch to me. If it was a relay,it would not work period.Not to mention, the switch controls the dash lights too.

If you have a service vehicle soon light (not service engine soon) this usually indicates a problem with the foreward lamp system.Your problem seems confusing, but check your high beam lamp operation. These cars are NOTORIOUS for corroded harnesses to the headlights. The problem is usually buried behind the washer bottle or across the radiator area. If you are lucky, it may be a burned out high beam bulb. If the blue symbol for brights stays on and there is no click when pulling on high beam lever, you will need a new turn signal switch.

It the multi-function lever (turn signal) . When you pull back the handle ,this turns on the high beams headlights and indicator on the dash.