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power on stereo before entering truck

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=135708
Printed Date: May 14, 2025 at 10:57 AM


Topic: power on stereo before entering truck

Posted By: tony7758
Subject: power on stereo before entering truck
Date Posted: January 03, 2014 at 2:09 PM

I have a 2012 Toyota Tacoma. The aftermarket stereo takes one to two minutes to boot up and start playing. This is a common issue with new head units as they are pretty much a computer these days. The only similar post I found here was this old one with the subject.
"time delay relay stereo +"
I would like to solve two separate issues here.
#1. I would like for the stereo to start before I get in the truck. I want it to stay powered while I get into the truck and start the engine. Maybe one or two minutes of ACC circuit power to the stereo only. Possibly trigger off the door unlock alarm signal. I know the dome light comes on too but not for very long. I am not sure what would be the best way to do this circuit. I would think I need to trigger a time delay off relay for this modification. This relay would feed power to the acc wire to the stereo. There may need to be a diode to prevent back feeding the acc circuit to everything else in the truck. Please feel free to suggest another way if you think it would be better.
#2. I would also like for the stereo not to reboot when going from ACC key position to start. When I turn off the engine but do not remove the key. The stereo keeps playing now, with key in acc position. But when I turn the key back to start the engine, the stereo reboots. This happens when stopping for gasoline or taking someone to the store and waiting outside. I did find this post in another forum. But I do not see that my Toyota has an aux/acc power relay to hold in with a capacitor like this guy did. "kenwoodforums.com/viewtopic.php?f=39&t=4158" Maybe the answer is to add a relay and capacitor to the stereo acc power circuit?

Thanks for any help on both or either of these issues. I do have access to the factory wiring diagram for my truck. I do have the factory keyless entry, premium alarm system option on my truck. This truck had the non JBL stereo that I replace with a Kenwood DNN990HD.
Tony


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tony7758



Replies:

Posted By: davep.
Date Posted: January 06, 2014 at 9:42 PM
There are a myriad of different ways to accomplish what you want to do. Particularly with the "activate radio prior to entry". I'll suggest two phases.

A: Use this diagram to allow the radio to play until a door is opened. This circuit will also keep the radio energized during Start. If you want to keep the radio powered-up upon engine off, turn key to Accy before opening the door. A huge advantage to this circuit is that the all the wires required for this circuit except one, are located adjacent to the radio head, and the relays can be located close-by if there's room. The only wire you have to find is the door or dome light trigger. There are circuits for both positive and negative door triggers.

B: There are numerous other relay circuits in the "Relays" section. Using your imagination, you should be able to come up with ideas to power-up the radio on activation of Remote Keyless Entry. Personally, I would base my circuit around this on/off latching circuit. Note that a neg pulse on terminal #86 of the far-right relay will always turn the latch = OFF. Using diodes, it may be possible to isolate the LOCK function of the door switches from the RKE. Wire the RKE lock output to turn off the latch. This way you could lock the doors with the door switches without powering off the latch. But if you got in the habit of always locking the door with the RKE when your 'done' with the radio, you would always turn the radio off.

I would start with Phase A. It will probably be enough. It has been for me with my Alpines that have similar long power-up times. Phase B gets complicated, and the likelihood of a dead battery from leaving the radio powered-up increases. The simpler, the better.




Posted By: itsyuk
Date Posted: January 07, 2014 at 10:04 PM

what if you bought a dei 450T from ebay (frequently 30bux or less. i just bought an new extra one tonight on ebay for 9.99 shipped.) and had the "doors locking" pulse its trigger input and have the brake switch hook to its "ign" input wire and its ch3 hook a relay activating radio circuit .

program the 450t ch3 to "latched/reset w/ignition"

then when you are ready to head to the truck you would hit your lock button 3 times within 5-7 seconds and the 450t would turn on your tunes. after you start the truck, press the bake pedal and the 450t would release your relay letting the truck take over powering the radio.

i do a similar hookup in my roadmaster wagon because my pioneer has to inventory the (128GB ) flashdrive before it will play.

there are a few more things you could do with the 450t in there ... like have it turn your headlights on for 90 seconds if you press lock 4 times..it will do 6 things it might take some heavy braining to impliment all the channels.

on mine, i remote start the car. as i am walking out the door i have a seperate button combo that turns on the radio.

Its also handy in nice weather to be able to turn the radio on without keys in the ignition.... like at the drive-in movies.

download the owners manual from the12volt and mull it over. its a really cool little box.



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yuk
quiet rural missouri, near KC.
If your system moves you physically and not emotionally, you have wasted your money.





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