There may be a problem with the "plug and play" jumper. Maybe the wires aren't quite right. This is what you should have coming out of the unit itself. Red, ignition. Yellow, battery. Black, ground. Solid blue is only for power antenna. Blue white is power for the amp. Ignore the colors on the jumper. Connect the Red/white stripe wire from the dash to the solid red wire from the HU. Connect the pink wire from the dash to the yellow wire from the HU. Disconnect all other wires. Then one by one connect the speakers.
[_]☺☺[_] 96' Grand Cherokee Laredo 265,000 miles and still going strong.