Welcome to the SMD forum!
I have an 03 Silverado with a Pioneer SPH DA120, i have 3 sets of components and four 8" subs under the backseat. Recently i've been having a problem where my head unit will randomly drop down the volume and I wont be able to change it. I know its a problem with my headunit because it is killing the volume to my two mids and highs amps and my bass amp all at the same time. Also, it cant be my rca's because I have 4 channel rca's for my mids and highs amps and a separate set of rca's for my bass amp and I dont think there would be a problem with all my rcas at one time. Also the volume indicator on the screen of the headunit gets stuck. All of my power and ground wires for my amps are solid. I was wondering if anyone else has had a problem like this? The only two possible causes I can think of off of the top of my head are 1. my head unit is a POS and 2. the old factory speaker wires that arent used anymore but are still hooked up to the headunit wiring harness are grounding out somewhere and making the head unit go into "limp mode"?