Head unit wiring - don't shun me I tried existing threads

[Petebee]

So I have a relatively early ETA (2/85 prod. date) with the four speaker non premium stereo setup, including the fader switch in the dash.

I've looked at several threads on how to connect my head unit (old Alpine detachable face cassette deck) to the factory wiring. After removing some junk from previous stereo I am left with the following "free wires":


Wire Colors:
Red/Green
Yellow/Brown
Brown
Yellow
Blue
Blue/Brown
Purple/White
Red/White
White

Here are the wires that feed into the fader switch:


Wires that feed into the fader:
Yellow Black
Yellow Red
Yellow
Blue Black
Blue Red
Blue

Here are the speaker wires:

Left Front


Left Front colors:
Yellow Red
Yellow Brown

Right Front


Right Front colors:
Blue Red
Blue Brown

Left Rear


Left Rear colors:
Yellow Black
Yellow Brown

Right Rear


Right Rear colors:
Blue
Blue Brown

Pic of wiring diagram from receiver


I am pretty confident about making the connections for 12V power, main ground, switched power, antennae. It is the speakers that are driving me nuts.

I assume that the "free" blue and yellow wires in the dash deliver the speaker signal to the fader, which splits them L to R (or front to back). Do I just connect multiple speaker source wires from the head unit to either the blue or yellow wire? If so, how? Or do I hack into the fader switch by wiring to the corresponding fader wires, for example:

RF+ Grey (head unit) to Blue/Red (fader)
RF- Grey/Black (head unit) to Blue/Black (fader)
and so on...

Help! Wiring is not my strong suit for sure.

[StereoInstaller1]

Unwrap more, until you get to the Junction of the fader wiring and the deck harness. Go about 6" past that Junction and pray you see more yellow/brown and blue/brown wires

[StereoInstaller1]

You MUST have 2 wires per speaker at the deck, you cannot combine any of them

[Petebee]

Okay so I pulled the console panel and took a pic:



11 wires total
Yellow/Black
Yellow/Red
Blue/Black
Blue/Red
Purple/White
Red Brown or Grey
Yellow Brown
Blue Brown
Red White
Brown
White

The Blue and Yellow wires just led to the fader switch. I am thinking that the original radio just had L/R balance adjustment, and the fader switch adjusted signal for Back/Front adjustment. Original radio might have used the Yellow Brown and Blue Brown as the ground, Yellow and Blue as the signal to the fader, which then split it up to back and front. My left side speaker wires are all Yellow, and right side speaker wires are all Blue.

I unwrapped the factory tape (still intact) several inches prior to the junction with the head unit wires/fader wires and I can't see any evidence of splicing or cut wires.

How about this as a theory:

Right front speaker
Splice Grey (head unit) to Blue/Red (dash) for +
Splice Grey/Black (head unit) to Blue/Brown (dash) for -

Left front speaker
Splice White (head unit) to Yellow/Red (dash) for +
Splice White/Black (head unit) to Yellow/Brown (dash) for -

Right rear speaker
Splice Purple (head unit) to Blue/Black (dash) for +
Splice Purple/Black (head unit) to Blue/Brown (dash) for -

Left rear speaker
Splice Green (head unit) to Yellow/Black (dash) for +
Splice Green/Black (head unit) to Yellow/Brown (dash) for -

The above would eliminate the factory fader and front/rear speaker pairs on each side would share a ground (i.e. two head unit wires spliced into a single dash ground wire).

Does that seem reasonable?

[modernist]

Unwrap more, until you get to the Junction of the fader wiring and the deck harness. Go about 6" past that Junction and pray you see more yellow/brown and blue/brown wires

I think in the earlier cars with non-premium sound the ground splices are under the front seats, not in the dash. Not worth looking for. Mine is from 12/85 and is like that, anyway.

You MUST have 2 wires per speaker at the deck, you cannot combine any of them

YES. Don't use common grounds between speakers, that can fry a 4-channel amp. Bypass the fader entirely, it's useless. Use the factory + and – wires for the back, and run new + and – to the fronts. Be sure to twist the pairs, I failed to do that and ran into trouble with RFI. This was my troubleshooting thread, I also made a few diagrams.

(correct me if I'm wrong, not an expert. just finished doing my own stereo, however. came out nice)

[Petebee]

Thanks for the tips. I cut out the fader and used the factory speaker grounds for the rears. I'll run new twisted pairs for the fronts.

Deck powered up but antennae is not picking up reception too well...had to graft in a new end plug and didn't realize that there is a small wire at the center under the white plastic sheathing. Will recut and solder that joint and try to reinforce it a bit.

But the head unit works! Now to hunt down some cassettes LOL.

[StereoInstaller1]

Woot! Ya, coaxial cables suck... But you now have a grip on it, congrats!

[AndrewBird]

Add far as the antenna goes, radio shack sells connectors that require no soldering and work very well.