New member here. Just got a 96 yukon 4 dr. Having troubles with sound. All speakers worked good with stock radio. Then bought aftermarket and installed it. Hooked it all up right using pigtail to gm harness. 2 days later, sound cuts out. Every function works just no sound. If i turned on the wipers, radio would work for a bit. Thought bad radio, went back to stock radio to diagnose. Worked for 5 mins. Then went to turn up volume, it gets quiet. Turning volume down, got real loud for a sec then quiet. Tried reading other forums. Looked into it being the amp under drivers seat. Re-installed new radio, cut wires for rear speakers, sound came to only fronts. Got a new amp from parts truck. Re wired pigtail for sound to back speakers, plugged in amp, square 1 again with no sound at all. HELP??