1999 suburban 160,000 miles. When driving yesterday i noticed when i applied the brake my radio display went out ... when i turned on the headlights the radio came back on but the left turnsignal would not work. The indicator would come on but not blink also the cruise control would shut off and not function again until the lights were switched off and then everything would work normally except for the radio display. I assume a relay switch has taken a dump or could it be something more serious?

 

I'd start by taking a look at the back of the head lamp switch make sure nothing is melted or loose... might also try turning the dimmer all the way up and see if it changes anything....
Might also remove the column cover and check the blinker wiring harness for poor connection...

 

Sounds like a bad ground.

 

Battery connections. What's your volt gauge doing?

 

Replaced alternator 3 weeks ago no voltage issues. When lights are off and brake is pressed ,dash lights up . Definite clicking noise when brake is pressed like a switch is trying to activate or something also if I press the brake with no key in the buzzer goes off like you left your lights on after you remove the key