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"AestheticsInMotion" (aestheticsinmotion) 02/17/2018 at 15:53 • Filed to: None

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Wiring noob. I’m trying to power my stereo, and could use a more experienced eye so I don’t screw anything up. Check my work?

I need to hook all this up (well, the blue antenna lead is optional but may as well right?) I figured I’d wire nut everything and test it out before using the crimp style connectors I have.

Black to ground is easy, I put red electrical tape around the ground in my dash when removing the stock stereo.

Blue should go to the power antenna control listed below (light green/yellow, Miata radio harness)

So that leaves yellow, red, and blue/white to connect to the stock radio harness.

Yellow (constant 12v) should go to 12v battery (blue/red miata radio harness). This is what gives constant power, in order to keep presets and maybe clock time yeah..?

Red (ignition/accessory 12v) should go to 12v accessory?? (blue/black miata radio harness) this is what powers the amp when you turn the key and makes everything work. I think?

And then blue/white (amp turn on) should connect to.... Uh. Also to the constant 12v along with the yellow wire above..? This powers the amp, but looking at my total system I think the only connection between the amp and head unit is RCA cables? Does that sound right? Sorry, jumping into this after weeks of no work. I should have drawn out a diagram of how I’d connected everything...

This seems to be an accurate wiring guide for the stock radio harness. I ran new speaker wire so I don’t have to worry about the door wires. And the TNS (the nighttime system) doesn’t seem to be needed. I’m not actually sure what that is, possibly connecting the stock radio to the dimmer switch?

can I just use the stock radio harness for everything, or do I need to track down different wires? Any help is appreciated. Comically small Miata workspace for your time

MINIGTI > AestheticsInMotion 02/17/2018 at 15:59

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Close, Amp turn on is only needed if you have outboard amps, otherwise leave capped; same with power antenna, leave capped if you don’t have one. Constant 12v is actually the main current draw as well as holding memory. Ignition wire just tells it when the car is on.

OPPOsaurus WRX > AestheticsInMotion 02/17/2018 at 16:01

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I think u r supposed to use crimps due to all the bouncing/vibration not nuts

AestheticsInMotion > OPPOsaurus WRX 02/17/2018 at 16:02

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Just using nuts to make sure everything is working properly, assuming it is I’ll properly connect everything up. I just don’t want to crimp everything, realize I screwed it up and then gave to cut the wires and crimp them again

functionoverfashion > AestheticsInMotion 02/17/2018 at 16:12

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Red (ignition/accessory 12v) should go to 12v accessory?? (blue/black miata radio harness) this is what powers the amp when you turn the key and makes everything work. I think?

And then blue/white (amp turn on) should connect to.... Uh.

Red is what switches the stereo on when you turn the car on. So, if you have a tester, use the one that gives you power when you turn on/off the car.

The blue/white is the one that would trigger an external amp to come on, but if you don’t have that you can cap it with electrical tape.

So it sounds like you kinda had those two backwards? If I’m reading that right.

AestheticsInMotion > functionoverfashion 02/17/2018 at 16:15

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I should have mentioned I do have an external amp. So it looks like the blue/white should connect to the amp... I think I have everything sorted out now, thank you!

OPPOsaurus WRX > AestheticsInMotion 02/17/2018 at 16:56

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Sounds like a good plan

functionoverfashion > AestheticsInMotion 02/17/2018 at 21:52

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Yeah man, I’ve probably wired like, 30 of these. So ask away. I’ve also read a book called “The 12 Volt Bible” so... yeah

AestheticsInMotion > functionoverfashion 02/17/2018 at 22:55

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Those are some impressive credentials. Okay, here’s one. For the amp, the diagram says I need an inline fuse between the battery and amp, but it doesn’t give any specifications. I’m guessing there’s a certain size fuse I need?

Also, could I run that line to the same 12v constant that I’ll be using for my headunit or would it be best to go straight to the battery?

functionoverfashion > AestheticsInMotion 02/18/2018 at 08:08

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A standalone amp usually draws more than what the constant power for the head unit is rated for. In other words, the circuit that feeds the constant power wire probably has a small fuse, maybe 5 amp?

The amp should have a specification for what kind of fuse is required. And you should go direct to the battery if possible, putting the fuse as close to the battery as possible. It should probably have its own ground, too. But that doesn’t have to go to the battery. It’s wise to use a larger gauge wire for the amp’s power and ground, too. What is the amp you’re using?

functionoverfashion > AestheticsInMotion 02/18/2018 at 08:10

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haha, I mean, there are people who do this for a living. But I know enough to be dangerous, as they say.

AestheticsInMotion > functionoverfashion 02/18/2018 at 13:57

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So when you say larger wire... Are we talking like 14 awg..? It’s a Kenwood KAC-M3004

functionoverfashion > AestheticsInMotion 02/19/2018 at 08:36

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Looks like it says it will draw 22 amps, but that’s probably a maximum figure, not a continuous draw. So, a 25 amp fuse (or breaker) and it looks like 12ga. wire would be ideal. There’s a chart here:

http://www.offroaders.com/technical/12-volt-wiring-tech-gauge-to-amps/

I’ve definitely wired things without following such recommendations, and while they may work, it’s best to do it right once.

I’d also recommend using a circuit breaker rather than a fuse, if you can find one that fits your needs. That way if it ever does pop, you can just reset it, rather than requiring a fuse you may or may not have a spare for. Since I worked at a marina, I always used simple marine circuit breakers. Nothing about the “marine” aspect was the appeal, it’s just that cars tend to have fuses and a lot of boats will have breakers, and we stocked a whole variety of sizes. If you break down on the side of the road with a blown fuse of some kind, you can walk. If your boat breaks down, it can present a different level of problem. I think that’s the logic?