Install Head Unit with 2 12V Switched

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Beaver

Member - Posts: 2

Joined: April 02, 2005

Location: Canada

Posted: April 04, 2005 at 12:01 AM / IP Logged

I'm looking for some help on how to wire up my head unit so that I can wire up 2 different sources of switched 12v to the ignition sense wire on the head unit. I'm sure this can be done using diodes, but I'm not sure at the correct way of wiring them up to the head unit would be.

I have a switch on the dash that I use to control my video system and xbox. It switches between constant 12v, off, and switched 12v. This is so I can shut off the video system in the van when I don't want/need it running. It also provides flexability to have the video system on when there is no key in the ignition. The only problem is that I don't have the head unit working in this set-up when the vehicle is off, and I can't just use the common off the switch to wire to the ignition sense wire on the head unit (as is could have 2 sources of 12v at one time connected), cause when I want the video off, the head unit would be off also.

So how do I use the existing ignition sense wire that is currently hooked up to the head unit and also connect the common terminal from the switch for the video system to the ignition sense wire? Are diodes the answer or a relay set-up?

Any assistance that you can provide me would be appreciated.

Regards,

Michael

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Bmnicolosi

Copper - Posts: 173

Joined: January 26, 2005

Location: Louisiana, United States

Posted: April 04, 2005 at 10:06 AM / IP Logged

wire up a another switch that has 12 v constant to it. run the wire off of the switch to the HU. cut the ignition wire at the HU. use two diodes<face the stripes away from the HU. then connect the two back to the ignition wire running into the HU. now you can flip the switch and have the HU on or have that off and the car on and HU on. does that solve your problem?

If you say "I already know how", don't ask me a single question.

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the12volt

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Joined: March 07, 2002

Location: Louisiana, United States

Posted: April 04, 2005 at 10:28 AM / IP Logged

If one of the ways you intend to supply 12V+ to the head unit is via the ignition switch and the other is from your existing switch in the dash, the more practical way would be to use an SPDT relay.

30 to head unit

85 to ground

86 to 12V+ from ignition switch

87 to 12V+ from ignition switch

87a to 12V+ from existing switch in dash

Install Head Unit with 2 12V Switched -- posted image.

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Install Head Unit with 2 12V Switched

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