My Sony CDX-M30 Stereo keeps blinking off and on in about 2 second intervals, after several minutes it stops blinking and plays normally. Nothing I've tried has correced this.

could be thermo electronic component normally mounted on the inside of the unit...its to protect against over heating

Press and hold the SELECT button. (the setup display appears) Press SELECT button several times until Demo appears. Rotate the volume knob to turn Demo to off. Press and hold SELECT. This will return the unit to normal operation / display. Page 9 of this link to your Sony CDX-GT130 operating instructions. This guide encompases 4 similar models; CDX-GT330, CDX-GT33W, CDX-GT230, and CDX-GT130. Please note differences where indicated.
http://www.docs.sony.com/release/CDXGT33W_US_ES_FR.pdf

I have a Sony cdx 5090 car stereo, I don't have the manual for it. I need to know the wiring color codes for it to hook it up.

Have you tried cleaning the unit with a "Laser Lens Cleaner?" one that uses fluid? Mp3 is a fickle format and your deck may be having issues reading it. Try running a cleaner thru it. Secondly, when you burn discs, make sure you finalize it by making it "compatable for all player types" Hope this helps

try turning the radio off and hold down one the buttons until it blinks then adjust

hi there that is sorta the problem i had and if you press eject nothing happens its still in there what i done was disconnect the battery for at least one minute and the cd changer lost its memory and was fine so i ejected the cd magazine and cleaned all the cds and blew out inside the machine has worked everytime its woth a try

i resolved this myself in the end.
I unplugged the audio & power cables whilst the stereo and engine was running.
Then plugged back in.
I turned the engine off and stereo off as well.
I then unplugged audio and power again from the back of the CDX, left it unplugged for 10 minutes whilst the engine was still off.
I then plugged the leads back in and turned the engine on. the stereo recognised the CDX, but stayed on displaying "CD Checking". I switched to radio for 20 seconds, turned back to CDX and it selected CD 1 and has been good ever since.

I'm rather pleased with myself!

Steve

Have you tried using the reset button on the front of the unit (under the face panel)

You need to turn off the DEMO mode. It's on page 10 of the manual:
http://www.xplodsony.com/files/manuals/CDX-GT310_Owners_Manual.pdf

if it gives you a cd error message check the cd for scratches.try playing different cd`s