Main running power wire for stereo.

[Plex]

Hi I'm hoping someone will be able to clear this up for me. What wire provides the power for my radio when I'm using it. I always assumed it was the switched live ( ignition live), but someone has told me that it is what it says it is and it's just a signal wire from your ignition. And it's the constant live that powers the head unit when in use.

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[wew lad 5,000+ posts]

constant +12v is the power for the headunit, the switched ignition wire does not provide power to the headunit.

think of it as a signal for it to turn on, nothing more, nothing less, just an electronic signal to tell it when to turn on.

 

[Plex]

Is it OK to have them connected together my friend wraps cars and likes his radio in his van running when his van is turned off.

 

[wew lad 5,000+ posts]

You should be able to hold the power button on the headunit and manually turn it on when the car is off.

I wouldn't connect them together because it will kill the battery pretty fast, but he can if he wants... just make sure he knows what will happen.

Be sure that you only connect the headunit remote wire and the constant +12v wire together. do not connect the car switched ignition and constant 12v together, this is important.

 

[F150 2.1k]

^ This can be tricky, granted it allows you to have your radio on while the vehicle is off, but can start a lot more problems than its worth. Other than the obvious sign that it will always be on if not wired to a switch, you could trip your IOD (Ignition off Draw) fuse and it wouldn't allow the radio to play. I personally wouldn't tell a customer that its okay to run this application in there car, but I've seen people do it.

 

[wew lad 5,000+ posts]

^ This can be tricky, granted it allows you to have your radio on while the vehicle is off, but can start a lot more problems than its worth. Other than the obvious sign that it will always be on if not wired to a switch, you could trip your IOD (Ignition off Draw) fuse and it wouldn't allow the radio to play. I personally wouldn't tell a customer that its okay to run this application in there car, but I've seen people do it.

first time ive heard of an IOD fuse, isn't that only isolated to the switched ignition circuit? thats why i made sure to say only connect the headunit remote wire and +12v, and to make sure the ignition hot wire is isolated and not connected?

 

[F150 2.1k]

first time ive heard of an IOD fuse, isn't that only isolated to the switched ignition circuit? thats why i made sure to say only connect the headunit remote wire and +12v, and to make sure the ignition hot wire is isolated and not connected?

You were correct, my carrot to show the user I was talking too was inserted before you replied, so I thought it was going to the user before you //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif IOD fuses are commonly found in Jeeps. It is directly related to the ignition "ON" circuit for the vehicle, which includes the radio.

We had a customer bring in a 2001 Jeep Wrangler with the dash saying "Check Fuses" and radio wouldn't power on. He had hooked an amplified 12v antenna to the ignition switched "ON" and the constant (12v) wire. What happened was the antenna acted as a "pass through" allowing current to flow between the 2 wires, tripping the circuit and giving him the error.