[sooner65]

Few questions before trying to wire and install my new replacement radio for my 1965 Stang.

1. The new radio has a wire for ignition, battery and ground: The ignition and ground wires are easy as I can just attach them to the old wires. I may even ground the new ground myself as i have no idea where the original goes or how well its grounded. So, my first question is where is the best place to wire the constant power or 'battery' wire?

2. Do I even need the constant power wire for the radio to work? It doesn't have a clock and it's not programmable. What's the point really? I only want it to work when the key is 'On' or Acc'.

3. I want to test my wiring before i install the radio in the dash and the instructions say not to use the radio without least 2 speakers (haven't bought them yet). Will it hurt the radio to just give it power and see if it lights up when i turn the volume knob to 'on'?

4. With DC voltage, if you wire something backwards will it fry it or does it matter? I seem to remember it not really mattering in some electronics.

[65BlueHorse]

1. I wired mine right to the battery.

2. I don't think you need it to work but it probably does something or it would not be there. Even with the constant hot wire the radio will only work with the key on unless you wire both hot wires to the battery.

3. It should not hurt anything to turn it on without speakers but if the directions tell you not to you might want to wait until you get the speakers hooked up just to be safe.

4. I don't know. Sorry.

[sooner65]

After some reading through the forum, i'm pretty sure i was wrong about having a positive and a ground as the existing wires. They both seem to have positive voltage, one when the key is on and the other when the lights are on. So, I guess my new radio I should run the positive wire to the 'ignition' wire on the new radio, run the ground on the radio to the dash, and find somewhere fore the constant power to go. Should i just tape off the positive wire that is for the old radio's backlight?

[1965stang]

The radio shouldn't care if you don't have speakers wired up, all that means is that you can test it to see if it powers up and works, you just won't hear anything. Think of it like a home stereo - you turn on the amplifier without hooking up your speakers, the amp turns on but it doesn't do anything (you don't hear anything because you don't have anything plugged into it yet). Same concept, only it's a car radio.

For the constant power, get a test meter and test any wire you're thinking about using to see if it gets 12 volts, car on or off. You'll want to tap one of those. I'll have to get my diagrams out to check the radio light wire - I don't remember if that one only runs when you turn the lights on.

What kind of replacement is it?

[1965stang]

Almost forgot - point #4 you asked. You're right, some things it doesn't matter which way it's wired (like a fairly basic circuit, one called the "power" wire, the other the "ground"), as long as you're consistent, the power doesn't care as long as one wire carries the power and the other is grounded. A wire is a wire.

However, when you start getting into more complicated items such as the stereo, the internals are wired up a certain way that things designed to get power get them, and things that should be grounded, are. So yes, you will fry it if you ground the power and power the ground. Example - a guy I work with was helping his son jump his car, and he reversed the positive and negative cables. He fried the computer in the car along with who knows what else. Very pricey to have the car's computer sent out and fixed (I think he said it was a grand, I might be wrong though).

[Ivy66GT]

Originally Posted by sooner65

4. With DC voltage, if you wire something backwards will it fry it or does it matter?

Yes, definitely it DOES matter. You will fry nearly any electronics hooked up backwards.