Radio on till door open

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=48488
Printed Date: April 26, 2024 at 8:16 PM

Topic: Radio on till door open

Posted By: xmxer13
Subject: Radio on till door open
Date Posted: January 24, 2005 at 2:31 PM

I wired it up per the diagram and it doesent work. It keeps the radio on until the door is opened, but then the radio will not turn back on. I understand the latching part of the system, but after it has grounded and turned off the radio, where does it get power to turn back on and latch. Please help a new guy to understand.

Replies:

Posted By: 2intrigues
Date Posted: January 24, 2005 at 8:37 PM

I suppose this is the circuit you used...

In this circuit, the radio will turn on whenever accessory power is restored to the radio (i.e., key is in accessory or run).

Note that the "Radio's Accessory Wire" signal is spliced into the existing power feed to the radio. All this circuit does is tie constant +12 volts into the accessory power feed (via left relay contacts 30 and 87). When you turn the key to off (and kill the accessory power), all accessories remain powered via the fused +12 volt source.

To answer your question: Power to turn on the coil of the left relay is provided by accessory power to the radio (to coil terminal #86). The other side of the left relay coil (terminal #85) is grounded through the normally-closed contacts of the right relay (terminals 87a and 30).

Posted By: auex
Date Posted: January 24, 2005 at 9:12 PM

Can't link to diagrams on your hard drive.

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Posted By: xmxer13
Date Posted: January 25, 2005 at 9:48 AM

Got it now thanks, I was not splicing it to the acc. power feed, I was just hooking 86 and 87 from the left relay directly to the radios acc. wire.

Posted By: oil
Date Posted: January 30, 2005 at 8:07 AM

Can you use this system to keep the ignition power running therefore the engine keeps running till the door is opened without the key in??

Posted By: Zilverado
Date Posted: January 30, 2005 at 10:28 AM

auex]C wrote:

n't link to diagrams on your hard drive.

This is a pretty cool feature I have seen on some newer vehicles. Can I add it to any of my vehicles? If so, some clarifications would be good....

Radio Accessories Wire: is the power feed to the radio good enough, or must it be the Accessories wire in the ignition harness?
Fused 12V+: Is this just any 12V power source. In other words, can I install a new power source? What size fuse shoud this be?
(-) Door Trigger: I assume this is the door switch in the jamb of the driver's door (that turns the interior lights on)?

My appologies if these are silly questions, I just want to do it right.

Thanks.

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Zilverado,
Backyard Mechanic
1986 Chevy Truck & 1992 Nissan Pathfinder

Posted By: iskidoo
Date Posted: January 30, 2005 at 12:14 PM

oil] < wrote:

>Can you use this system to keep the ignition power running therefore the engine keeps running till the door is opened without the key in??

oil, just hook the wire from the relay that says "Radio Accessories Wire" to your Ignition wire instead. That will keep the Ignition on after you remove the key until the door is opened.

Posted By: Hoptup32
Date Posted: January 30, 2005 at 1:49 PM

Zilverado,

Power feed to the radio is fine.

Fused 12V+ can be any constant 12V source thats not controlled by the igniion switch. Use a fuse of the same size as installed in the fuse panel for the radio circuit.

Verify that your door trigger is (-), if so, just tap into it at the most convenient place in relation to where you place the relays.

Posted By: Zilverado
Date Posted: January 30, 2005 at 8:37 PM

Thanks Hpotup32.

I'll definitely keep this post for reference when I get around to doing this.

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Zilverado,
Backyard Mechanic
1986 Chevy Truck & 1992 Nissan Pathfinder

Posted By: stackrat
Date Posted: February 01, 2005 at 8:57 PM

2intrigues wrote:

Note that the "Radio's Accessory Wire" signal is spliced into the existing power feed to the radio. All this circuit does is tie constant +12 volts into the accessory power feed (via left relay contacts 30 and 87). When you turn the key to off (and kill the accessory power), all accessories remain powered via the fused +12 volt source.

You should put a diode behind where you tie into the radio power (i.e. between the fuse block and the splice)

This will prevent the other accessories from getting power, which is a good thing for two reasons: 1) You will not overload the wire/fuse by backfeeding power to ALL of the accessories through it; and 2) you will not be draining your battery down by running your A/C fan.