2002 Chevrolet Trailblazer instrumemt panel cluster

I have the back lighting turn signals but none of the gauges work (tech, Speedo, fuel, battery, pressure, temp.) Sometimes while driving they will all come on and stay on but a lot of the time on start up they don't work. Also the digital read out for the mileage and what gear I am in does not work. As well as only the lights on the factory radio control buttons are not lit up but the digital readout does work.I have checked the fuses they are good however occasionally the tbc fuse that controls the lights will blow. Can some one please get me a wiring diagram for the instrument cluster harness.I have no voltage read put to a2 (orange) a12 (white) and b7 (brown and white) what could be happening?