1996 gmc sierra dash light problem?

[StephenLance]

my 1996 gmc sierra ext cab short bed with a 350 and 5 speed manual trans has a wiring issue. the dash lights do work but blow the fuse before 30 seconds go by. ive replaced headlights, running lights, bulbs, connectors, i even stuck a 30 amp circuit in and that pops. on the circuit is all of the dash lights on the dashboard, rear running lights, and front marker lights. thats how it is from factory. my headlights, brake lights, turning signals all work. while the dash lights and marker lights are working the entire wiring of the truck plus the motor (computer ran) bogs down and lights dim. this is becoming very frustrating due to i cant legally drive it in PA at night. my last resort is taking it to a garage. HELPPPP!!!