[dpoltzer]

Have a 1970 T/A and installed the refurbished Delco Am/FM radio in it. I installed two new 6x9 speakers under the rear package tray. My question is what wire on the stock radio harness do I use to power the speakers. I believe it is the solid green wire that is loose behind the radio but when I connect the speaker wires to this green wire, I get no sound. I do know that the radio works as I can tune in stations and very faintly hear what is playing. Any ideas on wiring in the non stock speakers to work with this stock radio? Thx.

[OG68]

Are the speakers 10 ohms? If it's a factory radio (that hasn't been gutted or just a faceplate) it requires ten ohm speakers, at a minimum, 8 ohm. Anything less and you may have damaged the radio.

Just about all aftermarket speakers are four ohm.

[dpoltzer]

They are Kenwood 4 ohm impedance. Radio is bone stock.

[Bill Hanlon]

Wire the 2 speakers in series and you'll have 8 ohm.

[dpoltzer]

Then do I use that one green wire?

[unruhjonny]

I have heard of people saying running the incorrect ohm speaker on our factory decks can wreck them, but having blindly done it for several years, I can say I haven't experienced any issues... but since I know different now, I will do my best to run the correct ohm speakers.

The ohm rating aside;
Aftermarket speakers want to have dedicated grounds;
our cars were built so that the car body is the ground.

Green is for the front (or left) speaker;
And a blue wire is for the rear (or right) speaker.

The great thing about Pontiac radios is that they physically have stamped in the case at the plug which spot is for what wire.

Incase you are unable to look at the rear of the case on the radio to identify which spot is for what;
The wire plug is marked A through E
A = black/ground
B = green/front speaker
C = yellow/power
D = grey/illumination
E = blue/rear speaker

I hope this helps!

[OG68]

Originally Posted by dpoltzer

Have a 1970 T/A and installed the refurbished Delco Am/FM radio in it. I installed two new 6x9 speakers under the rear package tray. My question is what wire on the stock radio harness do I use to power the speakers. I believe it is the solid green wire that is loose behind the radio but when I connect the speaker wires to this green wire, I get no sound. I do know that the radio works as I can tune in stations and very faintly hear what is playing. Any ideas on wiring in the non stock speakers to work with this stock radio? Thx.

Do you have the stereo or mono radio? It makes a big difference on how to wire the speakers. The stereo radio should have a small circle on the dial to indicate stereo operation.
Is this the original radio?.

If you have a mono radio you will only have one speaker output. Some mono radios (AM or AM/FM Mono) come with a fader that allows you to adjust the balance between front and rear.
As best as I can recall for the Firebird, the AM/FM Stereo has four speakers (kick panels and package shelf) and allows you to adjust for balance

The green wire comes from the front speaker and plugs into the radio. If you wish to use your current speakers you need to adapt them for use with the factory radio or just plug in the front speaker only. And as mentioned earlier the early factory radio systems utilized the car body as the ground or negative side of the speaker.

But first you need to determine what type of AM/FM radio you have.

[unruhjonny]

Originally Posted by OG68

Do you have the stereo or mono radio?

Good point.

I assumed that this was already determined to be a two speaker radio;
The mono radios will not have provisions for the rear/blue wire to connect to anything.

When I compare two AM radios I have here;

The case has the plug imprint on my mono radio reads (L to R):
GND (has lead; A spot in socket)
SPK (has lead; B spot in socket)
12V (has lead; C spot in socket)
LAMP (has lead; D spot in socket)
GND (open/no lead; E spot in socket)

The case has the plug imprint on my two speaker radio reads (L to R):
GND (has lead; A spot in socket)
SPK (has lead; B spot in socket)
12V (has lead; C spot in socket)
LAMP (has lead; D spot in socket)
RSPK (has lead; E spot in socket)

[dpoltzer]

It is a stock GM AM-FM unit with the red dot that lights up. It was not original to this car. I do not see anything on the dial that says "Stereo". Dave

[OG68]

Its a stereo. And 'Stereo' isn't printed out.
So now you need the stereo harness to plug into the back of the radio and at least two 10 ohm speakers. Plus the correct wiring harness from front to rear or modify your existing wiring.
Complete diagrams should be in the 70 Firebird only service manual

Our sponsor should have what you need.

[unruhjonny]

the rear speaker "loom" was an add-on blue/black wire pair that was routed under the drivers side sill plate to the trunk.

there's this part:
https://www.lectriclimited.com/rear-...harness-104962
and this part:
https://www.lectriclimited.com/speaker-harness-116897

[dpoltzer]

Thanks for the good info gentlemen. I will work on this over the weekend.