Turn on lead
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=2935
Printed Date: July 15, 2025 at 5:57 AM
Topic: Turn on lead
Posted By: mason55
Subject: Turn on lead
Date Posted: August 20, 2002 at 1:42 PM
Right now I just have an aftermarket head unit, amp, and subs in my Nissan Pathfinder. I'm installing a second amp and 4 speakers this weekend. Anyways, I know how to hook up everything in a 2 amp system except for the remote turn on lead. Instead of running a second one from the front I can just splice the one I already have, correct? I'm not really sure how to do this. Does it involve adding a second wire in the middle of the one that's running? Or attaching a second one to the end? Can someone please explain this to me? Thanks
Replies:
Posted By: crroush
Date Posted: August 20, 2002 at 2:10 PM
A remote wire is usually wired to a switch/relay inside the amplifier that if it receives a 5 volt signal or whatever it opens the gate and the amplifier can turn on. I have used the same remote wire multiple amps without a problem. Even if you ran a second wire, you still would have to splice into the remote/ign wire of the head unit twice, so why not do it in the trunk! good luck Craig
Posted By: mason55
Date Posted: August 20, 2002 at 8:21 PM
Ok, I understand how the turn on lead works. What I don't understand is how to relay it to a second amp from the first.
Posted By: DeathsJester12V
Date Posted: August 20, 2002 at 8:29 PM
Mason, you could either Splice it in like you're talking about, which is okay to do, hell a lot of installers do it on a two amp system...but the correct way is to use a relay... here's a link: https://www.the12volt.com/relays/page5.asp#rtol Jsut replace the word fan with amp....that's how it's done.... ------------- Đễẳ†ђş 12\/ Ĵęśŧē®™
Posted By: JellyNutz
Date Posted: August 20, 2002 at 8:38 PM
You dont have to use a relay... Thats only if your head doesnt supply enough voltage to power your second amp, in which case I'd use a transistor...
Posted By: mason55
Date Posted: August 21, 2002 at 11:21 AM
Ok, if I want to use a relay to be safe, where's the best place to get a 30A SPDT relay? I'm looking at my radio shack catalog and they have "30A SPST Automotive Relays" What's the difference between single and double throw, and will an SPST relay work?
Posted By: sparkyssb
Date Posted: August 21, 2002 at 11:42 AM
You can use a SPST relay for this application. The SPDT has an extra pin which allows a connection between pin 30 and 87a when there is no power to the relay. (thus making the connection break if there is power supplied) If in fact power is supplied, pin 30 and pin 87 will have a connection. So in reality, you should probably use a SPST relay for your needs. The 5 pin is not needed. This is your hookup with an SPST relay: 1. Pin 86 = (+) Remote turn on lead from head unit
2. Pin 85 = (-) Ground
3. Pin 30 = (+) Power / ----------These two pins can be switched around
4. Pin 87 = (+) Amp turn on terminal \ ---------- However, I like my installs this way Take care and hope this helps! 
Posted By: mason55
Date Posted: August 21, 2002 at 11:53 AM
Thanks a lot for your help. Guess I'm headed to Radio Shack tonight. One last question... Do I just tie both turn on wires to pin 87, or should i just tie one and then splice a second one on to that? Hopefully I can just tie them both on and save a little work...
Posted By: sparkyssb
Date Posted: August 21, 2002 at 1:35 PM
Um..which two turn on wires are you talking about? the one coming from the stereo to pin 87? No...dont do that. If you are talking about the two turn on wires for both amps, then yes, you may certainly do that. no problem there. 
Posted By: mason55
Date Posted: August 21, 2002 at 1:45 PM
Indeed, the wires going to the amps. Thanks for the help. Considering it's $5 for a relay and the safer option (plus makes for easier expansion), I'll do that instead of being all ghetto and splicing wires. Once again, thanks for all the help!
Posted By: sparkyssb
Date Posted: August 21, 2002 at 1:58 PM
You got the idea... Hey, no problem on the help. It's the least I can do while sitting here at work doing nothing.  hehe
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