jeep switch 12v problem

Alright, i am installing a aftermarket head unit and i hooked up everything and it wouldnt power on. So i started doing trial and error things and i found out that my 12v switch wire coming from my jeep does not work. i can put the 12v constant and switch together and it powers up but when i have the constant to constant and switch to switch it will not. what could the problem be? thank you

enemen8 wrote: Alright, i am installing a aftermarket head unit and i hooked up everything and it wouldnt power on. So i started doing trial and error things and i found out that my 12v switch wire coming from my jeep does not work. i can put the 12v constant and switch together and it powers up but when i have the constant to constant and switch to switch it will not. what could the problem be? thank you

also know as the acc wire

Don't connect power to things that don't work. If it is the Acc wire as emenen8 suggested, then you are constantly powering your Accessories - hence possibly flattening the battery. If you do know what that switch controls, then it may be ok (to connect). I just wired in a new HU and as always, it is straight to the battery (with fuse at the battery of course!). (I used to include a 2-way selector switch for +12V or Acc power, but I canned that last millennium.) If you want to add a switch, the add one. Use only existing switches if they are otherwise disconnected. And if your switch wire is the ACC line, then as above - check connections and fuses. And test it on BOTH Acc & Ign key positions!! (It should be off otherwise - ie, when cranking and with key-switch off.)

The factory radio do not work inside the car anymore but did when i took it out. I checked all fuses and only had to replace one but it wasnt the problem. It is a 1996 Jeep Grand Cherokee.

and thank you oldspark and toyyoda for the responses.

The accessory (switched) wire going to the radio should be RED / gray. If this wire is not getting voltage then check fuse #1 (10A) in the passenger side kick panel. If that fuse is good, then the wire might be cut or damaged in some way. In that case running a new accessory is your best option.