wiring spdt relay with multiple accessories

Hello. I have a currently have my amp turn-on, Ipod charger (it's an A/V to Ipod dock connector w/ charging), and FM Modulator spliced to my radio's turn-on wire. I have been reading that a relay is much safer so I want to do that. The diagram 'connecting additional devices to the remote turn on wire' is pretty straightforward. I'm just confused to how I wire points 86 (remote turn on) and 87 (constant 12v +).

1. For 86, do I splice into my radio's turn on wire? Or cut the remote wire; wire it directly to the relay, then connect the remote wire that is still attached to the radio, to point 30?

2. For 87, can I splice into my radio's constant 12v+ with a fuse? Or do I have to get the 12v+ directly from the battery?

I appreciate any help.

P.S. I looked around and found that the Ipod can draw up to 500ma when scanning songs. The amp turn-on, and fm mod would draw up to 100ma max; so I figured the combined draw of all connections would be under 1a. Go with a 1a SPDT micro relay?

I would use a standard 30A automotive relay.

The remote out from the radio would ONLY go to the (+) coil (pin 86).  You could use the main 12vdc from the radio at pin 87 but you should fuse it down to a max of 5A or so. 

Thanks! So I think I follow regarding pin 87- splice the constant 12v+ wire from the radio and put a 5a fuse between the relay and wire.

I'm still confused though on pin 86. Can you paraphrase the term 'radio out'? The way I understand it, the radio harness only has a remote in (the radio receives the input signal from the remote wire telling it to turn-on). Is there a separate out wire that I should be looking for or am I just way off here?

rocgalant wrote:

---

Hello. I have a currently have my amp turn-on, Ipod charger (it's an A/V to Ipod dock connector w/ charging), and FM Modulator spliced to my radio's turn-on wire. I have been reading that a relay is much safer so I want to do that. The diagram 'connecting additional devices to the remote turn on wire' is pretty straightforward. I'm just confused to how I wire points 86 (remote turn on) and 87 (constant 12v +).

1. For 86, do I splice into my radio's turn on wire? Or cut the remote wire; wire it directly to the relay, then connect the remote wire that is still attached to the radio, to point 30?

2. For 87, can I splice into my radio's constant 12v+ with a fuse? Or do I have to get the 12v+ directly from the battery?

I appreciate any help.

P.S. I looked around and found that the Ipod can draw up to 500ma when scanning songs. The amp turn-on, and fm mod would draw up to 100ma max; so I figured the combined draw of all connections would be under 1a. Go with a 1a SPDT micro relay?

---

rocgalant wrote:

---

Thanks! So I think I follow regarding pin 87- splice the constant 12v+ wire from the radio and put a 5a fuse between the relay and wire.

I'm still confused though on pin 86. Can you paraphrase the term 'radio out'? The way I understand it, the radio harness only has a remote in (the radio receives the input signal from the remote wire telling it to turn-on). Is there a separate out wire that I should be looking for or am I just way off here?

---

The radio has a switched power lead (the red wire) that tells it when to turn on.  It then has a remote turn on output (usually blue or blue/white) that tells other devices to turn on.  This output is what you want.  The relay coil should be the only thing connected to this wire.

Ok last question. So I am trying to get a SPDT and of course, it's not available in my area. I tried auto shops, electronics shops, general wholesalers, home improvement stores...nothing. So I was wondering if I could use a SPST 30a relay instead? Would that basically mean that whatever is wired to it, will always stay on since there is no 87a (Normally Closed) contact for the relay to rest at?

https://www.the12volt.com/relays/page5.asp#rtol

Sorry about multiple posts. Just wanted to give an example- So if I wire an Ipod charger (approx 1a), FM Modulator (2a), and Amp remote turn (under 1a) on to a SPST relay, would those accessories continue to draw power from my battery even when the car if off? Would I have to install a switch?

rocgalant wrote:

---

So pin 86 (the remote turn on wire) would serve the same purpose as having a 87a (NC)? Pin 86 will tell the relay when to 'activate?'

---