Car Stereos: No power to my head unit., dc volts, fuse box

Question
Ok so i was trying to reattach my ground to my capacitor. It sparked when i put it back on. I went to turn the car on and my cd player was only lighting up on the little spot that shows you where to put the cd. I tried resetting the cd player and still nothing. Well a few hours later the little light where the cd goes in stopped working also. I checked the fuse on the unit, the audio fuse in the fuse box, and the fuse on the amp, the capacitor still lights up and so does the amp but no power is getting to my head unit. I'm not sure if there is a fuse on the wire kit that clips into the back of the unit but is there any other things i could check?

Answer
Hi Joe,

The best way to troubleshoot a deck power issue is to use a multimeter to check the voltage of the power wires in the head unit harness.

You don't need an expensive meter; as long as it has a DC voltage function, a $10 meter will work fine.  Set the meter for DC volts; if it's not an auto-ranging meter, set the voltage range to 20V.  Connect the black probe to the deck's black ground wire, or just touch it to the deck chassis.  Use the red probe to test the voltage on the yellow wire and the red wire.  

The yellow wire should show 12 volts at all times; the red wire should show 12 volts when the ignition key is in the "accessory" or "on" position.  If you're not getting power on one of the two wires, you'll want to check your fuses again.  Remember that your car will have two different fuses that supply power to the radio; the constant power wire and accessory power wire are always fused separately.  Often one of the fuses is shared with other accessories, so it might not be labeled as a "radio" fuse.  Be sure to check for a fuse box in the engine compartment.

Hope this helps!

Brian