Ok. I realize this is more technical than mechanical, but I thought I’d give it a try. The stock OEM radio in my jetta died, so I bought a used one online. 1 out of 2 problems were now fixed. I can now see digits and response on the lcd of the radio, something I was glad to see. However, still no audio. After getting frustrated with the car several times, I realized that if i jiggle the plug, sometimes having to remove it and plugging it back in, wiggling it in in the process, some, not all of the speakers come to life, which was more than I had before. However, I have to now do this every time the head unit loses power, either by turning the car over or just powering it off for the night. I have researched this extensively and some have pointed on a possible faulty speaker plug making the amp think there is a blown speaker, therefore rendering all channels down, to a bad amp, to bad wiring, to a bad used oem radio. I checked all the fuses and they are fine. I would hope someone out there would know what I should do. PLEASE HELP!
How old is the Jetta? You need to determine if it is the wires, plug,speakers or radio. All can be fixed. A car audio shop is likely your best choice.
If you used those 3M quit-tap splices ( the ones you squash down with pliers to mate one wire with another ), GET RID OF EVERY ONE and either solder splice or crimp butt-splice.
I’ve had nothing but trouble with every scotch-lock splice I’ve ever had. Even the ones that worked for two years eventually lost contact due to the partial contact they produce initially and the corrosion over time therein.