Got it!! I had the right wires, but the HU needed to be changed to push the fader back. Weird?
Either way I am very happy!
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Here is a very and easy summary for anybody who searches so my 3-4 hours spent doing this could be done in 30mins tops (seriously)...
You DO NOT NEED to purchase an aftermarket $25-$30 wiring harness. This can be avoided....albeit a little more messy, but I wont be swapping the headunit ever again, so who cares?
This will work on 87 and earlier models I can tell you for sure....not sure about later years as I have searched, and some W124 models use different colored wires at the Fader...so this should clear up much confusion for the earlier models. This also "should" work for all NON-OEM-Amp setups with only a change in the fader's wire color. You can determine the new color by simple elimination. Just do all steps and skip the fader until the end then just cut it and do one-by-one while playing music til you find the right wire.
Disclaimer: Please remove negative cable from battery while doing this and ensure you have a fuse built into the headunit, or add in your own on the +12V constant wire.
Step1: Remove shifter + A/C wooden cluster then Cigarette Lighter. There is a DIY on this.
Step 2: Remove OEM Becker Unit. Remove power cord, Speakers L + R (2 channel), Chassis Ground and the Antenna.
Step 3: Cut the original Becker power harness off -- It will have 4 (four) wires. Wire them up with harness on new headunit.
OEM-Harness-Side:
Blue = Power Antenna
Brown = Ground
Red/White = Ignition +12V
Yellow/Black = Constant +12V
There is
no illumination wire if your harness has one.
So match the names with the new harness. Pretty straight forward.
Step 4) Now head over the fader. Cut it off completely and pull out the following wires:
Black/yellow (+): power to left rear speaker
Black/white (+): power to right rear speaker
^ (Thank you to BodhiBenz1987 for the correct wires)
These are the only two wires you need. Tape up the exposed remaining wires for safety reasons.
Step 5) Run new wires from the Black/Yellow and the Black/White up to the headunit. Tape/Solder them to the positive wire for the respective speakers as shown above on the hew headunits wiring harness.
Now, behind the headunit, there are a total of 4 (four) little connectors as shown in the picture below:
Above you can see the male and female connectors. You only need the male one.
Front speakers: They were directly plugged into the 2 channel L + R in the beginning. Simply gut the male connector and attach the green to the positive (+) and the black to the negative (-) on the new headunits wiring harness. On the little male connector, it will have a L or R imprinted on it so you can tell. I would label each connector with tape for ease at a later date if anything comes loose or w/e.
Rear Speakers: There is NO grounds at the fader....instead, you should now have TWO remaining speaker male + female plugs left behind the headunit. Each of these will still have a L or R written on them. You are ONLY using the ground (black wire) from these. Wire the grounds to the new harness. Now, take your new extended positive (+) wires that you made from the fader, pull it behind the headunit and attach it to the positive (+) for each speaker wire at the new headunits wiring harness.
At this point the speakers should be working fine.
Step 6) Attach Chassis ground (my headunit had a bendable piece of metal that it attached to...Had to pry it up)
Step 7) Attach antenna
Step 8) Test if you have not already.
Might be a little confusing....but print it off and read it with yourself in front of the wires. Ask me if you have any other questions.