Car Stereos: 1999 Jeep grand cherokee after market head unit install, jeep grand cherokee, panasonic head unit

Question
So I have installed a Panasonic DVD, CD, Radio head unit however when i turn it
on the radio works but CDs, dvds and the AV plug ins don't work. I cannot seem
to figure out why all the wires match up and are connected correctly!

Answer
Hi Paul,

This is an extremely common issue in these vehicles, and has a very easy fix.

Here's what's going on:  your Grand Cherokee is equipped with a factory amplifier.  The amp is controlled by a wire in the factory radio plug.  When you apply voltage to this wire, it turns on the factory amp.

You probably purchased an adapter harness to connect your Panasonic head unit to the factory radio plug.  There's a blue wire in the adapter harness, and it matches up to the factory amp activation wire.  When you installed the head unit, you connected the blue wire in the adapter harness to the blue wire in the Panasonic harness.

The trouble is that the blue wire in the Panasonic harness is a power antenna wire.  It only supplies voltage when the "tuner" function is selected on the head unit.  That's why the factory amp turns on when you're listening to the radio, but turns off when you switch to another function.

There is a wire in the Panasonic harness that will work better: it's the blue/white wire.  This wire will supply voltage whenever the head unit is powered on, regardless of the source selection.

So, to sum up, you need to disconnect the blue wire in the adapter harness from the blue wire in the Panasonic harness; then connect it to the blue/white Panasonic wire instead.  The solid blue Panasonic wire should not be connected to anything at all.

This is a case where having all the wires matched up and connected correctly is actually the source of your problem.  Once you switch the wires, though, everything should work perfectly.

Hope this helps!

Brian