Not sure if this is an issue with the car or the radio, but I pulled a pioneer head unit out of my other discovery to put in my 1993 discovery. The 93 has an ISO adapter already wired in, so I bought an iso to pioneer 16 pin adapter and plugged in the radio. It popped on and off at first, and I had to re crimp the ignition/12v wire and then after that the radio stayed on properly. It reads a disk, I can hear it, but it says muted no matter what settings I adjust and whether or not I turn the volume up or down. According to pioneer forums this means it is likely a grounding issue, but I traced the wire back and it is grounded with no tears in the insulation. Another possible issue people identified is that the “ipod/cellphone mute” wire is grounding itself out, but my connector doesn’t have a wire there. Is this something I should investigate? Does anyone know why it went from working in my 1997 disco to being permanently muted in my 93?

pioneer deh 5000ub

Speaker inputs

Power/ground side of the connector

Back of head unit

 

PIN number 9 on the radio is the cell phone mute wire, it was hooked up to illumination from the car and getting a signal the whole time, muting the head unit. Unplugged the wire and it unmuted.

Pin diagram I used to see where the cell phone mute wire was