[unruhjonny]

I have one complete harness here that would be for a mono radio to an 8-track player, and I have three bits from another harness;
I suspect that one of these partial harnesses is for a two speaker/stereo radio to 8-track, because the radio plug has the 'E' slot filled with a blue wire, and the dash harness to 8-track wire plug has again the 'E' slot filled with a blue wire;
I have understood that the blue wire in any of these looms was reserved for the rear speaker.

I would like to use these partial harnesses to create a correct functioning 8-track harness to use with a stereo radio.

Does anyone have any picture of this style harness that they could share?

____

I am sitting here BEFORE hitting "post" on this thread, and by process of elimination I am wondering if I have accidentally figured it out without requiring a picture of any sort.

Please tell me if this seems correct;

The loom for a mono radio and and 8-track player has:
1) the male plug for the radio with the 'E' slot empty, and two black wires in the 'A' slot;
2) the female plug which accepts the dash harness radio plug has slots for 'A' and 'E' empty
3) the rear speaker signal comes directly from the 8-track player plug

The loom for a two-speaker radio and an 8-track player has:
1) the male plug for the radio has the 'E' slot occupied by a blue wire, and the 'A' slot is empty;
2) the female plug which accepts the dash harness radio plug has slot for 'A' empty
3) the rear speaker signal comes directly from the radio plug which has it's signal routed through both the 8-track, and the radio (male) plug.

It looks right now like a fundamental difference is how the two are grounded, as the stereo radio wiring lacks a ground for the radio plug (assuming everything except the 8-track plug is in tact on this one chunk of wire), while the mono radio plug retains the ground.
I am also sitting here wondering if that ground is missing on the 8-track to radio plug, or if it was done that way to trigger how the radio signal is cut out.

Here is my take/understanding on the dashboard radio (male end) plug wiring setup:

A = black = ground
B = green = front speaker
C = yellow = positive
D = grey = dash lights
E = blue = rear speaker

My car is a single speaker car, but I have been contemplating changing this, and to that effect I have purchased a two speaker radio, which I could combine with a really nice 8-track player that I have had boxed up for the better part of twenty years now... this is one of those little details that I hope to have figured out before my car is done.

I earnestly look forward to any feedback I might receive.

[RAJ7395]

I recently parted out a 69 firebird with an AM radio and a four speaker 8-track player sound system. The cars build sheet confirmed that this was factory original. It had two kick panel speakers and two in the rear package tray. The center dash hole was empty.

[unruhjonny]

neat!
I didn't know that was available!?

Here our cars max out at two speakers till 1980!?

on the left is the complete mono radio to 8-track loom I mentioned, and on the right are two partial looms from which I hope to make a two-speaker radio to 8-track loom.

[RAJ7395]

Here's some images of it and the wiring.

[unruhjonny]

Ok, it appears as though I am stumped again.
(I haven't picked this up in several days)

this is where I'm at:



The partial loom on the left side may have been from a mono radio to an 8-track player, as it's 8-track plug (eight slots; female connector) is the same as my mono radio to 8-track player loom.
The partial loom on the right side is undoubtably from a two speaker radio to an 8-track player.

The left end has black and light green with black strip wires that are on in my loom on the right;
The right end has a solid light green, and a light blue wire.

This is the two speaker radio connector end:



This is the other end:



I am wondering now if I made a mistake in connecting dark blue to dark blue, and should have connected a rear speaker wire in there;
I am guessing that the rear speaker connector would have had two dark blue leads in at the top slot to connect to both looms dark blue wires, and that the black lead from the left loom connects to the black wire from the rear speaker loom.
... the more I think about this, the more I am incline to think this is a big mess up right now.

That leaves the light green, and light green striped wires... maybe they connect??

And does the empty slot on the 8-track plug need a light blue wire lead to it?

Help!?

I am sure I have enought to

[unruhjonny]

wait a second!

I forgot that I have this partial loom (car side) here that is set up for a two speaker radio;
This seems to have the rear speaker plug on it, unlike the car side loom for a single car speaker radio - which moves the rear speaker plug to the 8-track loom...
So maybe I didn't mess up in connecting the two dark blue wires from the two sides of the 8-track loom.

I am now wondering if someone previously removed the black/ground wires from the radio plug ends, as this car radio plug has the black wire on it.

[Held for Ransom]

Jonny,
Do you know how to read schematics?

[unruhjonny]

that is great!

Where are those from?

I searched high and low in the documentation that I have, and could find nothing like that.

Last week, after it seemed no one here was able/willing to share anything that might assist me (for over a week) I reached out in a facebook group and two members of the group I posted in quickly helped me;
One shared with me what his stereo radio connector was pinned like, the other shared a schematic similar to this one.

This was a modified picture I made after I was told how the 8-track plug was pinned on a stereo radio loom:


Then this was the schematic shared:


Long story short, I ended up with this:


It's a couple inches longer than the mono radio connector that I have, but that's ok.

I actually modified it from the schematic because the partial loom I had indicated it was pinned/set up a little different than the schematic;
Since I had a car side plug from a two speaker car that had the right speaker integrated into it, my modififications essentially move the point where the rear speaker loom plugs in.



To be clear, this forum is my go-to for any help or information because if I have the question odds are at some point someone else can benefit from it, so I'd much rather use this forum over facecrap.

I am considering this a closed case, and I decided to not bump this post last week because I didn't want to make a nuisance of myself by bumping a post that no one seemed to be involved with.

Thank you very much!

And just incase anyone here can use it (or this works), here is a link to the post I made - it is in the group 'second gen graveyard':
stereo radio to 8-track loom help

[Held for Ransom]

That was from the '73 Pontiac Service Manual. In the accessories section, near the back of book.

[unruhjonny]

Originally Posted by Held for Ransom

That was from the '73 Pontiac Service Manual. In the accessories section, near the back of book.

Oh, ok.

I have a 1970 service manual, the Firebird supplement, and a 1971 service manual... that is missing an undetermined portion of the back of the book.

I did flip through what I had, but found nothing of that sort... then again maybe I was looking in the wrong spots(?).

['ol Pinion head]

will throw the following out, i apologize for the length of the post.

Just completed parting the lowest mile partscar I've ever owned, & have hauled in over 300 A-body partscars in the last 35 years. That particular Pontiac plant built '72 Lux LeMans I had kept for two decades as an example car to aid in the restoration of two other '72 Pontiac plant builds. This particular '72 has been outstanding in confirming detail after detail. One odd thing I noticed years ago, was two factory speaker grilles on the original package tray. Had always peaked my interest, as I had only had GrandPrixs & '72 & '73 Grandvilles & Bonnes & one Buick Electra with two factory installed rear speakers. Upon preparing to remove the steel package tray & catwalk structure, finally popped the clips on the cardboard rear speaker surrounds, & removed the speakers. Sure enough, the original owner had made a jumper wire from the factory pass side speaker to add on the drivers side, another 10 ohm speaker (which he must have sourced from the dealer). Not sure how a factory AM radio sounds with a single front speaker & two factory rear speakers, we already pulled the dash so did not try & test. From my minimal electronics experience, I would think for the rear speakers...to have much volume, one would need two 20 ohm speakers (which I don't believe were ever made). Maybe not, as this AM radio has the rear seat fader on it, & that I would assume would allow one to adjust more to the rear. Still don't "get" the added speaker setup & what it improved upon. Doubt the original owner experienced much satisfaction, as the car only racked up 4048 miles before it was rolled in the Summer of '72. Ended up being an insurance loss & sold to an older fellow who with no metal & body working skills tried to "fix" it & ended up holding on to it til Y2K.

Factory stereo's & 8 track units... in the very early 80's, I began boneyarding, definitely on a mission. Was heavily loading up on mid 60's-70's Pontiac factory options, hard to find trim, small pieces, as well as performane engines & tough to find sheetmetal. Buying partscars & projects began a few years later. Have had a ton of factory AM-FM mono's & FM Stereo's as well as factory 8 track units. One of the first early AM-FM 8 track that I pulled that was factory setup with two rear 10 ohm speakers was in a loaded out '72 B series. Cant remember if it was a Buick Electra or a Pontiac. Still have the 8 track unit. The plug on the rear of this pedestal mount 8track unit is unique, its a flat style & a bright orange color, much different than the previous style plugs used on typical '69-72 Pontiac usage 8 tracks. If you like, I can pullout the 8 track tubs & take pics of the harness plug & text them to you.

[unruhjonny]

that was a neat read!

I have been in the past called a 'throw back' which is intended to imply someone who is more into things from the past, or born a decade or more too late... I can only assume that were I older, I would have done much the same as you OPH

But because of my age, I have only found a small handful of period radios/players;
By the time I graduated in 1995 this stuff was all pretty darn scarce in scrapyards.

I wonder if the B-series used an 8-track player typically used in another GM brand - which might lend to explain the difference.

One of my other ongoing little projects like this is a multi end cable to bench test radios - and more or less make the spare stereo in my garage obsolete (and in turn free up much needed space);
One of the radios I have is from a 1975(?) Camaro, and by the looks of it, this unit was used on Venturas as well...

I have long understood that the 8-track players used in 70-77 Firebirds were all the same unit, and the differences in the loom connecting to the radio made the player function slightly differently.
Over the course of getting information to finish this loom, my understanding was confirmed.