Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Without looking at a diagram(if one even exists), I would say the black is the common ground, blue is left, green is right. Sometimes, GM radios have a wiring pin-out stamped on the cover of the radio....have you looked for that? Not all have it, but ya never know...
____________________________________ Joel Adams C3VR Lifetime Member #56 My Link
I've done extensive wiring with my original deco so I should remember but I don't. I do seem to remember there being a plug like that for each speaker but with only two wires each. I also remember a light green and a dark green. Is this a stereo radio or mono? Also it looks like the picture shows the convector (thing that looks like an external amp). Is that all intact and wired correctly? That would probably cause the speakers to not work if there were problems with it or it was missing. I agree with Joel though - definitely look on the radio for some stamped info on the connection details. Good luck!
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: email@example.com, 112 LSA, Eagle Steel Crank.
Here is some other info I found doing some searches online
75 came with either a mono or stereo radio. If there is only one
of the "convectors" then it's mono.
A mono radio has three wires going to one convector while the
stereo radio has six wires going to two convectors. The convector wires are
Yellow-Blue-Green. Both radios have a three wire bundle for speakers...black
for speaker grounds and a light green for the right speaker and dark green for
the left speaker. There is also another three wire bundle: gray ties in with
your parking lights to light the radio dial when you turn on your lights, black
goes to chassis ground, and yellow goes to fuse box for +12V power.
Convector wires are green, yellow, and blue. If the connectors are
cut off it will be impossible for you to tell the difference between a green
speaker wire or the green convector wire. Turn the radio upside down and remove
the bottom. The green wire to the convector connects to a terminal strip at the
very furthest connection point (closest to the top of the radio). Or bottom
connection as you are looking at it upside down. The green speaker wires are on
separate terminals closest to the bottom of the radio.
The speaker wires are black (common to both speakers) and 2 greens. It really
doesn't matter which green goes to which speaker as it is a MONO radio.
Use only 10 ohm speakers or you will cause severe damage to the radio. Most
modern radios use 4 ohm speakers, so be careful.
Outstanding help as always, thank you all very much. My radio is the stereo model but no wiring diagram is stamped on the unit. With the info you all provided I managed to get the speaker wired up only to discover the paper cone was torn apart. The wire leads were completely separated from the cone. So now I'm trying to figure which way to go, find someone to repair/replace the original speaker or replace entire system with new equipment. The rest of the car is 90% original and I don't know enough about what retains and what destroys value. Any ideas which way to go?
You could do what I did: on each of the two channels, I wired two decent quality modern 4 ohm speakers together in series, not in parallel as is typical for speakers. In series, the resistance ratings add together so I have 8 ohms per channel now which is probably close enough to the 10 ohm factory speakers. (Haven't had any problems and I've had it this way since last summer) In each of the pairs of speakers I kept one in the original dash location and then added another in the back - added bonus. I think it sounds pretty good, definitely better than with the just two mediocre quality speakers in the dash. I also added in a wired FM modulator so I can play an Ipod through the original head unit. More info (and a you tube vid) in this post.
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