77 radio wiring question

[Juskie77]

I'm restoring my 77 and putting an aftermarket radio in. The dash harness for the radio has 3 wires. A ground (black), a yellow (battery 12v), and a gray (instrument light). Most new radios have two 12v leads, a yellow for battery and a red. My question is where should I tie into the harness the red wire, because it isn't a factory connection? It is supposed to be be an accessory wire, so when the car is on or running the radio will run. Could someone point me in the right direction?

Thanks!

 

[navy2kcoupe]

I believe that the red wire should be connected to 12 volts "hot all the time" because its the voltage used to keep the
radio's memory settings intact. You can use the radio without connecting that wire, but any stations you "save" will be
gone when the radio is turned off. Just like when you disconnect your battery, all the stations that have been saved will
be gone.
Andy

 

[Juskie77]

I believe that the red wire should be connected to 12 volts "hot all the time" because its the voltage used to keep the
radio's memory settings intact. You can use the radio without connecting that wire, but any stations you "save" will be
gone when the radio is turned off. Just like when you disconnect your battery, all the stations that have been saved will
be gone.
Andy

That sounds more like the yellow wire, which has constant power. From the radio installation, it says "yellow, constant 12V", and the red it says "ignition/ACC". Maybe I should talk to the radio manufacturer??

 

[TimAT]

The manufacturers have overly complicated radio wiring- you have the GM harmess, and you know what each color wire is for. The yellow wire in your factory harness is only powered when the key is "ON" or in the "Accessory" positions. From your description of the radio's wiring diagram, it appears that that yellow wire (harness) should hook to the radio's RED wire, then the radio's yellow wire needs a fused, constant 12v+ to keep it's memory.

 

[Juskie77]

The manufacturers have overly complicated radio wiring- you have the GM harmess, and you know what each color wire is for. The yellow wire in your factory harness is only powered when the key is "ON" or in the "Accessory" positions. From your description of the radio's wiring diagram, it appears that that yellow wire (harness) should hook to the radio's RED wire, then the radio's yellow wire needs a fused, constant 12v+ to keep it's memory.

Thank you! The yellow wire is the accessory wire. You are correct. Thanks for your thoughts.