stereo was  turned off..   any every time i turn the car on it goes on .   why is it doing that?? i expect if i turn the stereo off then turn the car off, when i turn  \the car on it would remain off...  whats goin on here? batterry wire to bat and ignition to ignition....

any ideas???

Stereo brand?

Jvc. Wired correct.  Wonder if it’s supposed to come on all the time when car starts. Even if it was off before.  

Typically there's a yellow wire for ignition and a red wire for the power.  Did these possibly get swapped?

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4 hours ago, Shawninvancouver said:

Wonder if it’s supposed to come on all the time when car starts. Even if it was off before.

When it's off and you put the contact to on it stays off i expect? but after starting the car it starts playing.. that would be due to some spike-ing in your supply voltage, also could be a problem in your radio.. it should stay off..  (problem of these "modern" audio systems..)  a fat electrolytic capacitor over the supply (red cable + ) could bring the solution.. use a capacitor of 1000 uF/25 volt. (plus to positiv and minus on ground!!) 

Edited July 17, 20213 yr by dutchzcarguy

I originally hooked up as shown in diagram but it would not power up at all then I switched red and yellow and it powers on but turns in every time I turn the key on -  even if I turned it off prior.  

Can’t speak for all car audio systems. Installed car stereos at a shop years ago in college. The yellow wire was always constant 12v and the red was ignition switched power. Blue was auto antenna. The power amplifiers were normally wired the same yellow constant, red switched.

The constant power wire maintains the settings of the device.  He's probably losing that one.  A meter or test light would tell the story.

I have two power wires.  One constant and one switch.  I had them hooked up that way and the thing would not even come on.  Then I reversed them and it worked.  Maybe just a cheap arse jvc.  But I did watch a YouTube video abs his did the same. Came on when car came on

Check the red wire for switched accessory power. The wiring diagram is correct. If your not getting 12volts on the red wire that’s part of your problem. The way your describing it now the radio will stay powered on until you manually turn it off.

nope.. when i turn the car off, it goes off.... which is fine...  i am now thinking its supposed to go on all the time it gets power...

Looking at the wiring illustration you posted is correct. Did you buy this new? Possibility it’s the radio but you should have a switched 12 volts on the red wire. Need more information after you’ve checked it with a meter.