Questions on 81 300D Becker to JVC change out - PeachParts Mercedes-Benz Forum

showme · #1 11-21-2009, 06:11 PM

I'm changing the stereo on my wife's 300D, and now that I've got it out, I've got a few questions.
A) Is there a coupler made to join the Becker R\L speaker plugs to RCA type connections to keep from having to change the original wiring?

B) There's a brown wire that's been cut and left hanging (see photo). What's it for? The cigar lighter still works.

C) There's a red wire with a female end of a blade connection that's not going anywhere. (Also in photo) Any ideas on what it's for?

Thanks for any help on this. Especially how to jump from Becker's pin and blade speaker connection to an RCA.

cscmc1 · #2 11-23-2009, 12:07 PM

RCA speaker connections? I have never seen those type used on a car stereo; usually those are only for preamp outputs, aux inputs, etc... Are you sure you need to hook the speaker lines up to an RCA jack?

showme · #3 11-23-2009, 12:35 PM

Well, not exactly. Here's a picture of what I have, side by side with my Becker. The JVC has speaker lines coming out of the power plug, but it also has the RCA line out jacks, (only the rear are there, the fronts are blanks), which I thought would be there to serve the same purpose of the Becker L\R jacks. I don't really know, which is why I'm asking the forum. I've also included a pic of the Becker jacks.
The installation instructions just list the RCA as a line out, then list all the speaker wires going to the four separate channels. I just don't know if I want to get into splicing into the original set up, when there's a good chance that I may now send the OEM radio off to Becker to have it overhauled and an XM\mp3 jack installed. I can do it, but having to hack into the fader and existing power lines, which are neatly bundled in the power plug, doesn't sound very wise if I'm coming back to the Becker. If I could wire it with existing equipment, it would be nice.

cscmc1 · #4 11-23-2009, 12:41 PM

Ah, gotcha. The RCA jacks are there to connect the radio to a separate power amp -- unless you're going to be doing that, you won't use them. You'll have to cut and splice, I suspect, unless you can find a pair of the "female" connectors, which I believe might be found at the speaker end of things in a junkyard car. No big deal, really; you'll just cut the speaker wire, save the end with that connector for future use, and hook up to the speaker leads that come out of the JVC.

GeneE · #5 11-25-2009, 08:40 AM

1) You shouldn't connect the original speaker plugs to the RCA connectors on the back of the JVC. The RCA connections are almost surely pre-amp out (i.e., line level, not speaker level) connections. You don't need them unless you have a separate amplifier. The Mercedes speaker wires need to be connected to the JVC's speaker wires, but because Mercedes has a simple fader built in, you will only use the front or rear speaker output wires, two for the left, and two for the right, to connect to the Mercedes speakers. Regarding plugs, I happen to know you can get an adapter kit from Crutchfield that includes two plug adapters for the speakers, because the kit came with my purchase there. That is what you need to keep from having to cut your existing plugs off. I do not know whether these plugs are available from other companies.

2) Regarding the brown wire, if the '81 is the same as my '83 300d, on the car's original radio, I believe the power wires (which are wired into the plastic insert that plugs into the original radio) are as follows:

Brown = ground
Black = switched 12v (comes on with the key)
Gray = illumination 12v (supposed to switch on when you put on your lights - I ignore this one)
Red = constant 12v (to keep your stereo presets etc.)

This would mean that the brown wire is ground, and someone cut it to separate it from the Becker, instead of loosening the connector on the back of the Becker.

3) Regarding the red wire and female connector, I don't recognize it. As I said, red is constant 12v when it is part of the main plug going into the back of the Becker, but I don't know what that female plug could be for. Hopefully someone else can help with that one.

Good luck!

showme · #6 11-25-2009, 09:51 AM

Thanks so much for the replies, Gene and Harry C! That's the information I was looking for. Now to get it done. I really appreciate the help. What a great forum, and great people!

ps2cho · #7 11-25-2009, 03:18 PM

This is what I did for my 87...it should be pretty much the same. I bypassed the fader

Quote:

Originally Posted by ps2cho

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!

--------------

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.

showme · #8 12-20-2009, 12:23 AM

Hey, all, it's been a while, but here's what's transpired. I called up Crutchfield (my first dealings with them) and they sent me the wiring harness for the speakers and the original adaptor for the power plug, plus the DIY papers for $26 bucks shipped, which was good. The power plug didn't match up. It had two male knife's instead of the 4 pin connection, so I called them and they told me that there was a change about 83-84, so we deduced that someone had changed the head and it's fittings with it. Yes, there was electrical tape. No, I didn't think about that. Anyway, Crutchfield is sending me the new harness -no charge- as soon as they get them back in stock. So this has been a wierd one all the way around for me. Good news is, I got a Crutchfield catalog, and now I know what I know my wife really wants in there!

Thanks for the help, again. and I'll update when I get the right wires in.

Yak · #9 12-20-2009, 12:06 PM

I ordered a JVC head unit from Crutchfield yesterday and they'll include the harness (when it comes off backorder) for free with the purchase. This is the one I expect:

http://www.crutchfield.com/App/Product/Item/Photos/Default.aspx?i=120701860

For wiring ID in your original pic, the strange looking female end on the red wire that goes nowhere looks like the back half of an old push-and-twist inline adapter for a glass fuse. They used to be common for radio installs. That would seem to match up with a PO having installed something different at some point in the past. There's a pic of a similar item here

http://www.action-electronics.com/fuses.htm#Holders

It MAY still be hot and/or switched with the ignition. I'd follow it back to see if it's connected to the cigarette lighter. The lighter works regardless of whether the radio wires are connected. And, yes, the radio will still light up and 'look' like it's working even with the "radio" fuse pulled and the lighter wiring disconnected - it has power for the lights, but it won't produce sound. I checked that out in my '83 300CD a while back.

There's a harness stub/connector that pigtails from the lighter to the radio harness shown here:

Keeps blowing fuse. A little help?

Installing radios seems to cause blown fuses due to the numerous circuits that interact there. I think fuses 1, 2, and 4 are all upstream of the radio and affect constant power, switched power, and the console lights. Since you've got evidence the PO did something else in there, I'd recommend removing the ashtray (two screws, I think) and try to isolate any mods he did.

showme · #10 01-03-2010, 09:35 PM

Still waiting. I wonder if they've started the assembly line back up yet?

But I really am impressed with all the detailed information that everybody has provided. Man, what a forum.