My kdc-mp538u the screen will not come on what can i do

Car Radio Constant 12V+ Wire: Blue/White
Car Radio Switched 12V+ Wire: Yellow/Red
Car Radio Ground Wire: Black
Car Radio Illumination Wire: Red/Black
Car Radio Dimmer Wire: N/A
Car Radio Power Antenna Trigger Wire: N/A
Car Radio Amplifier Turn On Trigger Wire: N/A
Front Speakers Size: 6 1/2?
Front Speakers Location: Doors
Left Front Speaker Wire (+): Blue/Green
Left Front Speaker Wire (-): Gray/Black
Right Front Speaker Wire (+): Red/Green
Right Front Speaker Wire (-): Brown/Black
Rear Speakers Size: 6 1/2?
Rear Speakers Location: Rear Deck
Left Rear Speaker Wire (+): Blue/Yellow
Left Rear Speaker Wire (-): Gray/White
Right Rear Speaker Wire (+): Red/Yellow
Right Rear Speaker Wire (-): Brown/White

It could be dirty contacts on the back of the faceplate. Have you tried to clean the metal contacts? Use a pencil eraser on the contacts and try to get them nice and shiny. If the contacts are hard to clean with an eraser, remove the faceplate and replace it on the deck several times and see if that helps. If the deck still doesn't work properly, try a reset by hitting the reset button with a pen tip. It is located below the volume control.

make sure you have power going to both the red and yellow wires. also make sure you have a good ground connection.

you can try cleaning the laser lens, or have a professional clean it for you.

try disconnecting power to the radio. either unplug the wire harness or disconnect the battery.

go to kenwood web site download and print hope this helps

My issue was that I didn't have the blue "amp" wire hooked up and I had a factory amp.

I have had the same problem, my problem was that i accidentaly hooked up the constant wire to the switched, and the switched to the constant, causing it to turn off completely, resetting everything. So if this is the problem then just switch the wires in the back of thew head unit, should be the fatter yellow wire, and the fatter red wire
hope this helps

Check your ground wire

They dont work with classic ipod for direct ipod connection, also try updateing the firmware in your ipod this is a common problem, deck looks sweet tho eh?