Ok, been searching all over the internets for this, but can't find an answer. I installed a Sony Xplod Head Unit in a 2006 Cobalt. After buying an aftermarket harness adapter, the install was quite easy. However, the radio will operate just fine for a while and then shut off. Sometimes it works for hours, sometimes for minutes. Sometimes it stays off for a few minutes, sometimes for a day or two at a stretch. Usually it gets "streaky" once it shuts off once. That is, it may work fine for a day, but then shut off and once this happens it will only work for a few minutes at a time before shutting off again and repeats this cycle quite a few times until hitting a good streak.

Here are some additional details:
1. The radio will shut off/on while driving at virtually any speed, but also happens when the car is sitting still.
2. Most people diagnose it as a ground connection problem. I connected the ground directly to the factory stereo ground and this connection is SOLID.
3. It is not overheating. The radio will sometimes not work immediately when starting the car in the morning. Several times I have had the radio out when it turned off, and it was not hot (nor even warm) to the touch.
4. The 12v switched power is connected to the fuse box wiper fuse through a fuse tap. This connection reads 12.5V while at idle.
5. The 12v constant power is connected to the 12v constant connection the factory stereo was connected to. This connection reads 8.5V at all times I have measured it.
6. The head unit harness has a blue wire that reads "AMP REM"...I did not connect this to anything, assuming it was an optional connection to turn an aftermarket amp on/off, but the radio manual wasn't super-clear about it.

Any ideas what the problem is? I'm guessing it is related to the 8.5V coming off of the constant wire, but that seems a bit off. The radio should be powered by the 12.5V coming off of the acc. wire when the car is running anyways. As far as I understand it, I could choose to not connect the constant wire at all if I didn't mind losing my presets, etc everytime I turned off the car, and the radio should still work off of the acc. wire when the car is running.

 

with the car on both acc and constant idealy should read 13.8 so i would test the voltage on the pins of the factory harness (ur harness can still be plugged in just flip it so the back of the harness is towards you and shove ur MM leads into the power and ground then leaving it on that ground try the acc crimp cap and see what it says)

Its probably going to be a connection problem. where idk but the only way ur gonna find out is by ruling each indivdual connection out. so test at the radio harness then again at the next connection down then at the aftermarkert car harness then at the other stock side of the car harness then at the fuse box. Wires in the car itself could have gone bad but chances are probably not. its probably going to be a loose/half blown fuse or loose connection or crimp you did so hard it broke off the wire and its all half assed now (yes ive done that b4) ect

 

shop wired my remote sub wire to my interior lights. i had bass in the shade and not in the sun. double check the power and ground

 

It's a Sony!

And I'm not saying that cause I don't like Sony headunits, I have a really nice one in my Cavalier. a MEX-5DI. But it does the same thing too. It used to do it more so when I first got it. but still does it now. I've sent it in to Sony 3 times, and nothing yet. (The first 2 years I had it, I had it in the car for a total of 5 months. ) I'm pretty sure it is a Power issue, in that the Power coming in gets to low for it.

Most of my issues were when I had 3000 watts RMS running in the car and a stock Alternator. I changed out the Alt and had less problems, and now that the car is my winter vehicle, it has about 300 watts RMS in it with the HI-output alt, and only shuts off once or twice a winter. (Cold weather where the belt doesn't grab the alt as well as it should, and the cold alt is harder to turn too, makes my check gauges light come on till it warms up)

I gave it a dedicated power line, and 3 grounds, all of which helped too. I think it just has a "touchy" range of operation.