Weird problem with Sony CDX-MP40 headunit


Junior Member
Hi there,

I'm new here and trying to find some answers //

I've got the following problem:

Yesterday I installed my Sony CDX-MP40 headunit and everything went smoothly so far.

When I start my car (or turn it on ACC) the headunit turns on, takes my cd and starts auto-playing it and I hear the music too (so far so good). But, he doesn't do anything else! It doesn't react on anything anymore! It's not reacting on the buttons on the front itself, and neither on the remote control. So I can't get into the settings, can't turn up or down the volume, can't skip the number, totally nothing!

Only one button works, and that's the 'OFF' button. (Weird huh)

Another thing I checked is that even when I open the front I can't get my CD back, because the eject button doesn't react either! So it's not only the front that's not working. Though the display works and keeps scrolling this demo mode, where it says Sony, Equalizer, 7 presets etc.etc. a promotional demo, but when I try to turn the 'Motion Display demo' off (according to the manual SEL + 4) it doens't react on that either.

I already tried cleaning the connectors and checked my power supply.

Anyone has any clue at all? I think it has something to do with that demo thingy, or maybe some kind of 'safe-modus'? I really don't have a clue.. //

Would be great to have some answers, or at least some things to try!

Thanks in advance! : //



There should be a reset button in a paper clip sized hole, visible when the face plate is out of the way. Try pressing this to get things back to normal, if this doesn't work, its RMA time (Return Material Authorization).

yes...I was swapping out my stock battery in my jeep after installing my eclipse 8443 HU, and when I hooked the battery back up and turned on the car, all that was on the display was "SECURITY". It would play the cd at an unaudiable low volume and all the buttons were disabled. This was Eclipse's Security Network (ESN) stuff built into the HU to make the HU worthless if it gets stolen. Long story short, I had to call eclipse and they identified me through information given on my registration card and then they walked me through four layers of security on the deck! After that everything was fine.


I'm having the same problem now with my Sony audio, doesn't react to anything...but I bought the car with it so I don't have the papers. Does this mean I can't reset/unlock it any more because of this security issue??


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