Ive tried 2 differrent wiring harnesses in my 03 sierrea my pioneer head unit and nothing worked so i tried it with another stereo and harness and got the same result, would i have to custom order a harness from Pioneer

 

I don't quite understand your question.

From my experience, there are two harness you'll need to install an aftermarket radio, a harness that comes with your radio, and plugs right into the back of the radio with cut wire ends on the other side, and a wiring harness that plugs into your truck's OEM radio connector.

Usually metra makes these OEM to aftermarket radio harnesses. Your job is to connect the wires from the Metra harness to the radio's harness in order for the radio/speakers to work.

 

I connected them correctly but they just wont work, i know sometimes if a car has onstar you might need a special harness but that costs like $100 and thats ridiculous