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Wiring a Aftermarket Radio [Negative Ground]

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EastTXMidget

Freshman Member
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Hey All,

I am looking at putting in a new aftermarket radio into my Midget tomorrow. I am relatively good at installing these things in cars that have pre-existing wiring harnesses, but looks like the previous owner destroyed it when he installed his old radio. My main question is where is the best place to run the Red and Yellow wires to? I believe that yellow is constant power and red is switch power. I looked at my wiring diagram, it looks like it runs constant to the fuse box and switch power to the lighter. Just looking for some advice. Thanks!!
 
Constent power to the fuse box is good, but switched power should go to the ign, switch or a switched part of the fuse box.
 
Oh, afraid I have no idea, use a multimeter and see which turns on and off when you use the ign.

Hehe, I'm you can see a bugeye guy but elec is elec.
 
Any green wire is hot with the key on and fused already.
Solid brown wire should go to the radio yellow (memory).
On a 70, there should be a sub harness coming out from the middle of the dash. Brown went to the lighter, green went to the radio.
 
You are correct I just want to point out that the yellow wire if connected to unswitched power will be pulling the battery down when the car is not running. This can be averted if you chose to do so by running both power leads to a switched power point. Alternativly a battery minder can be used to keep the battery charged when the car is not used and the yellow wire is connected to constant power.--Fwiw---Keoke
 
Here is a tip I used when putting a Radio in Bugsy my '68 Sprite. I picked up a subminature Single Pole/Double Throw Switch SPDT from Radio Shack. I mounted this switch to the bracket that supports the bottom of the dash on the left side. Takes a 1/4" hole in the bracket for the switch. It only sticks out about a little more than 1/2" and does not interfere with anything. Now since the Spridget does not have an Aux position on the Ignition, I wired power to the Radio to the center contact of the switch. One contact goes to a switched power source that is powered when the ignition switch is turned on. The other contact goes to a always hot 12VDC source in this case, a lug attached to the side of the solenoid. Both sides of this switch are properly fused.

Normally the switch stays on the Ignition Switched Side however if I pull Bugsy into the garage and need a few tunes, all I need to do is reach into the car, flip the switch and radio comes on. This setup provides power as needed without worrying about points burning out or fuel pump running. Slick setup and you are the only one who knows this is there.
 
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