Just separate all the grounds... if you fish the wiring out of the center console you can see that all the speakers have a + and - wire running to them... if you get it all fished out you will see what I mean... you should have two red wires and two green wires and then there will be four black wires total...

This is all assuming you have four speakers in the car already....

(This is how my '83 300D was... I just did it on Friday so it's still kind of fresh in my mind )

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'98 E300 Turbo "Juliette"
'85 Federal 300TD

Hey Cap, I had 1 red, 1 green, 1 red/black, 1 green/black, two blacks (these were all connected to the fader in the center console), and three black 'soldered' together (that were in the same bundle of cables, just hidden further in the sheath).

In addition to that, I had the original 4 cables that were connected to the radio but from what I've read, these are the 'imposter' cables.

Does it matter which ground I use for each speaker (i.e. doing the battery test to see which speaker blips)?

Thanks for the help! I am new to all of this so I am learning on the fly.

Good job with the battery... if the speaker "blips" then you have the correct + and - for that speaker. The speaker shouldn't make any noise if you dont have the right ground.

You might not have traced the wires far enough back if you don't have "8" wires. Basically you should have four "colored" wires and four black wires... you need to cut the grounds apart that are connected together. Follow the wires towards the radio opening. IIRC There are a set of the connectors like the ones that plugged into the back of the radio where the rear speakers connect to the wires that plug into the fader switch. you can get rid of the connectors and now you will probably see what I'm talking about.

If you still aren't quite sure take a picture and post it of the wires you're talking about. You shouldn't need any extra wire for the speakers. Just one wire for constant power. You can splice into the emergency flasher wire that has constant power and just run a short wire (maybe 2') up to the radio and then you will be golden. I found this idea on the forum so I wont take credit but it's a good place to splice because you don't have to run a long wire up into the dash.

-David

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'98 E300 Turbo "Juliette"
'85 Federal 300TD

Hey Cap,

So I went a little further back and I found some more ground cables... so now I have 11 cables!! (that were in the sheath)

I have:
1 green
1 red
2 red/black
2 green/black
5 black


I attached some photos. Also, to what does the gray/purple illumination wire attach to? Thanks again!






(see more here: http://www.flickr.com/photos/37518110@N03/sets/72157624403069354/)

This isn't quite true, at least not in the W123 coupe and probably sedans.

Yes, there are 6 wires at the fader. And yes, there are 4 wires at the factory radio head; but two of those wires are different ends of the same wire (Rd/Bk = L; Gn/Bk = R).

If you want to eliminate all guesswork, remove the factory fader harness and UNPLUG (yes, that's correct - unplug) the rear speakers from the fader harness. You may need to remove the center console, but you know for sure where your wires are.

If you're determined to cut, then on my factory '83 300CD harness, the solid green wire = RR, solid red = LR; the black/combo wires in this sleeve both are FROM the radio and TO the front speakers; green = right, red = left.

There are SIX black wires, not four. Two from the radio to the two separate solder junctions and four from the speakers. The solder joints are about 15-18 inches away from the factory radio plugs.

There's nothing magic about the wiring, and the 123 did have a "common ground" for each side. That's what the blob of solder is.

I am installing a new unit on w201 but it is the same problem as the w123.

Instead of cutting the wires at the fader, can't you just 'tap' onto the wires you wish to have leads to?

the fader is going to act as a resistor within this design and should not cause any problems - fader bypassed.

*this is a question as much as it is a statement.

If the W201 and the W123 have the same fader harness, then they share a ground, so if you want to isolate each corner, no, you can't just tap into the wires.

If you don't want to cut any wires but don't want to run new wires to the rear speakers, I think there are a few options: you can unplug the rear speakers from the fader harness and run new wires to the front speakers.

Or you could possibly unplug the fader switch, disconnect the rear speakers from the harness and pull those wires forward to the head unit (possibly enough slack), and then use the taps on the respective sets of now isolated front and rear speaker wires.

Either way, you have to unplug everything and/or cut something. I unplugged it and ran new wires to the front only and re-used the rear wires in my '83 300CD.

I am keeping the stock radio but my fader is shot. Can I just wire nut the three wires on each side of the fader together and have equal speaker feeds on all four corners?

btw I have a subwoofer and a factory amp in the trunk.

The speakers are in parallel at the fader. I called Becker Service department and asked if I wire nutted the three wires on one side and the three wires on the other side together would I just have full power to all four speakers and he said "yes". I took my console apart, pulled the fader and blew it and the plug out. It works perfectly now. I believe this is a good first step when diagnosing the Becker system.

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1985 300D

Do you have the speaker wiring gif in higher resolution for the speakers?

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'96 C220 138,000mi, '95 E300D 239,000 mi., '87 300TD 214,000mi '88 6.2 Turbo Diesel Chevy Conversion Van 253,000 mi.

Try right-clicking and open in new window. The lines are legible then.

But since this thread has a fair amount of confusion and mis-information, maybe starting a new one with a specific request and/or problem might be more useful.

Or you can look here for the FSM page for the W123 radio wiring: post 54

240d frying radio fuses

I put a new headunit in yesterday, opting to use this thread and the old wiring for the rear speakers.

I re-wired the front speakers because it was easy. The rears, however, are obviously a little more complicated.

I was checking out the sheath feeling for the spliced in grounds. Beneath that bundle I spotted two pairs (green/black and black, red/black and black) of wires that look exactly like the speaker wires that plug into the original headunit. I found these under the console, in the front-right corner, right under the sheath that carries wires to the fader. I was confused why these speaker wires weren't in the sheath with the others.

Additionally, right in this spot the wires were split by a connector, identical to the plugs at the headunit (one flat prong, one round prong, on a round plug). This connector is also found south of the rear speakers. I unplugged the two sides, and tested the prongs with a 9-volt. They made the rear left and right pop, respectively. I pulled the rear speakers to check the color coding, and found that my rears (84 coupe) are wired with red/black, green,black striped wires and black grounds, not solid red and green as the guide here says.

I'm curious why these wires are here, in front of the fader, if they ran to the rear speakers. They did not appear to just feed into the fader, or the sheath. They are four separate wires from the six at the fader. Just in case I tested the connections at the fader with the 9-volt to see if I could make the rear speakers pop, but got nothing with any combination.

I went ahead and used running wire splices to tap into the +/- of the wires that i found, and ran new wiring from here to the new headunit. Viola, seems to work great.

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1984 300CD

Post #20, above: "If you want to eliminate all guesswork, remove the factory fader harness and UNPLUG (yes, that's correct - unplug) the rear speakers from the fader harness. You may need to remove the center console, but you know for sure where your wires are."

The rear wiring on the coupes (and others, maybe) plugs into the fader harness, but is long enough to be snaked all the way to the front.

The guide may refer to the colors inside the sheath, i.e. between the fader and the rear-plugs and not the colors of the wires from the plugs to the speakers. I used to have a picture of the removed fader harness, but can't find it. The harness is with the new owner.

I agree that on the coupes anyway, tracing back and unplugging from the soldered/split/multi-wire harness is the cleanest way to go.

I read post #20. I agree the cleanest way may be to snake the bundled wires back through the cave. Doing this and clipping/dismantling the fader harness, however, is not the best way to keep things intact so you can re-install the factory radio if you need to.

No body has mentioned the wires i'm talking about, and tapping into them seems like a pretty good way to avoid dismantling the fader as well as spare you from re-wiring the rear speakers. My concern is that i'm still unwittingly passing through the fader. The fader harness is unplugged, so I don't think this is possible. Has anyone tried testing the rear speakers with a battery at the fader harness?

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1984 300CD