Wire for radio

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Joined
Apr 22, 2013
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Location
san diego
My Car
1973 mustang convertible(some day)
I'm installing a slidebad radio and it needs a key on, constant, and ground. In my radio area I have one plug that I cant figure out. the two combined purple/white seem to be a key-on. the blue/red has 1ohm resistance to ground so I don't know what that is or if this plug it for the radio? Any help would be appreciated.



 
See page 5

https://www.7173mustangs.com/images/1973_full.pdf

I'm not great at reading wiring diagrams, but it looks as if the light blue with red is back lighting maybe?? (IE comes on with lights)
I checked for voltage and light blue with red comes on with light switch. I don't need that I guess. Before I hack up the plug I was hoping to make sure is is meant for the radio. Anyone else know for sure?

Also, I need a constant. Take it off the fuse block I guess?

 
Yes, that plug is ACC power (white/purple) and lamps (blue/red). Another good place to tap into battery power is the circuit breaker for your e-flasher and brake switch, or splice into the cigarette lighter (blue/white).

 
That is the connector for the radio power and light. The white/purple stripe wire is key on and runs through a 15 amp fuse in the fuse block that it shares with the emergency flashers, back up lights, and wipers. The light blue/red stripe wires are used for all dash lights that are dimmable.

 
Ok, possibly dumb question about this.  The two purple/white wires that are for accessory power.  One provides power and the other completes the circuit to ground?  If yes, which is which?  Let me know.

Thanks!

Scott

 
Ok, possibly dumb question about this.  The two purple/white wires that are for accessory power.  One provides power and the other completes the circuit to ground?  If yes, which is which?  Let me know.

Thanks!

Scott
That's a negatory.  The other wire (blue/red) is lamp power for the radio.

 
I guess I'm wondering if both of the purple and white are hot leads, why are there two of them? That seems redundant. I'm sure there is a perfectly logical explanation that is eluding me here. The other question though was, if both the purple and white are hot, does it matter which one I use?

 
I guess I'm wondering if both of the purple and white are hot leads, why are there two of them?  That seems redundant.  I'm sure there is a perfectly logical explanation that is eluding me here.  The other question though was, if both the purple and white are hot, does it matter which one I use?
Yes, both are hot (fused) leads.  Why are there two of them?  As I tried to explain, there are a number of devices chained together, so there has to be a wire coming from the first unit going to the unit in question and a second wire returning from the unit in question to a third unit.  If you use only one of the wires, and ignore the second wire by leaving it hanging, there will be other units that will not get voltage.

 
Yes. Both wires need to be on the same side of the splice.

 
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