So I have had the same CD deck for probably around 4 years, I had it in my old car and now in my scion for over two years. Everything has been fine with it, I had the professional install by a respected shop and all.

Now, however, the deck will stay on when I turn the car off, even when I take the keys out and walk away. I have to actually turn the thing off every time I turn off the car. This is a weird problem that has never happened before.

Any idea what would be causing this and how I can fix it?

 

Wow, um... never heard of that happening before. I suggest that you have you xB exercised by a priest, fallowed by a voodoo dance.

Seriously though, your head unit must not have been wired up using the "normal" methods. When you turn off your car, the the ignition wire that your HU connects to should power down making your HU power down as well. If it is staying on then that means your HU is receiving power from some other source. The only way to tell would be to take a look at the wiring back behind the head unit. Also, have you done any mods to your car that might cause this? Other than that, I don't know what could be causing this. I know some people wire their HU to work when the car is off, but since you say that it has not done this before who knows what it could be.

 

sounds to me like there is some wired crosssed some where between the head unit and the factory harness..

 

Most likely you have a chafe somewhere in the harness. I just had this happen to my starter relay wire, where the engine would try to start in Run, not just Start. If the insulation on the 12V accessory wire gets chafed next to a wire carrying 12V battery power, your radio will always be on, even with the key out. Check any spots where that harness runs and you may have done some work, and look for damaged insulation. If you can see copper through the insulation, that's where your problem is. Fix is to wrap with electrical tape, and the 3M liquid insulation helps as well for an environmental seal. Quick check would be to turn the car off, disconnect the negative side of the battery, and do a resistance check using a multimeter from the 12V accessory pin of the stereo harness to the positive battery lead. If it's less then the MegaOhm range, you have a wiring issue.

Other possibility could be a short inside the radio between the primary and accessory power leads, good luck.

 

Yeah I have wired quite a few accessories around the car, most likely causing the problem.

It gets even weirder though now. If I turn off the car, the raido stays on. However, if I have something plugged into the cigarette lighter, and I turn off the car, the radio turns off. So weird! I guess I am going to have to dig in there on my day off and see what I did wrong with my wiring, or what came loose. Thanks guys!