Swapped red and yellow wires on my JVC KD-R200, then swapped them back. Now it only powers on when I push the Eject button. Otherwise, nothing

Yes pretty much just check the colours on the plugs line up,some companys swap them around sometimes,but 90% plug and ur done,sub prob has its own rca out put or there ll be a few less wires going to nothing when u plug in.if they have a coded security number make sure u know the code before u disconect

Problem with KD-R200 or KD-AVX33?
What does it mean by "it lights up blue then nothing?" Does it takes CD in?

is this a headunit you have just installed? if not then I am not sure, but if it is, try swapping the red and yellow wires over. One should have permanent live, the other should be switchable. (unless you want the headunit to stay on when the ignition is off, in which case put them both to a permenant live feed.)
Hope this helps.

try reversing your red (accessory) and yellow (constant) wire... also check the fuse on the back of the radio. and it wouldn't hurt to clean the connector between the faceplate and the radio either corrosion can cause this....

you have the red and yellow wire on the radio mixed up switch them

Check your wires they might be touching steel around your car mostly look at your yellow and red wires those are the 1' that give it power and light to your radio also check your radio fuse in the back.

Try rewiring it. Yellow to a full time hot 12v and red to an ignition switched 12v

I had this same problem...you probably have the wires wrong. Double check your connections for the red and yellow wires from the headunit. Make sure that your red wire is going to a 12 volt source that only switches on with the ignition.

Hi. your radio has 2 power wires. A red one and a yellow one (with most decks) It sounds like your radio is getting only constant power but no "key on" power. Check your radio with the key on you should have power on both the red and yellow wires. If you are missing power on one of the wires theres your problem. If you have power on both wires then there is something internally wrong with your radio...

As a sanity check run a temporary wire directly from the battery positive to the radio. Twist the red and yellow wires together and connect it to the wire from the battery. If this works either your red or yellow wire connection under the dash or to the harness is not hot like you think. Yellow usually goes to a constant 12 volt source (to keep radio memory) and the red wire to 12volts when the ignition is on. In some radios this is reversed. The test I mentioned will determin if the problem is in the wiring or the radio.