93 300E - Need help w/ wiring diagram for radio
I just recently purchased my first Mercedes - a 1993 300E. So far I'm loving it, but I've run into one problem: the stereo. This car was one of the models that had the Becker radio w/ the control unit, amp, cd changer, etc. in the trunk. The current system is no longer working and I'm wanting to install an aftermarket stereo. I know it's a big job requiring some pretty extensive wiring, etc. and I'm fine with that, but the one thing I haven't been able to find is a decent wiring diagram for my car (I'd like to tap in to the existing speaker wires, radio power, etc.). I purchased the Mercedes Shop Manual software discs and have them installed and while they have a ton of information on my car, they don't seem to have a wiring diagram & neither does Becker. Does anyone know where I can find a wiring diagram for this car? Is there anywhere online or perhaps even a book that might have it?
Thanks in advance,
Luke
If your car has a fade control by the window controls you will want to rewire that for much better performance from there you can determine which wires are for the rear speakers. Your new aftermarket stereo will come with a wiring diagram to help you out its usually on the top of the unit. I have installed so many stereos in so many different types of cars I can guide you through it.
1. Just buy a volt meter and clip off the old wiring harness from the stock Becker. (you can get a cheap volt meter off the internet)
2. Find which wire gives the radio power while the ignition is off it will be the RED WIRE on the new stereo
* you will need to also find the ground (its usually black).
3. Turn the ignition to the ON posision and find the power wire it will be the YELLOW WIRE on the new stereo
from here you have the power taken care of, next you can wire the speakers up. if you have the fader then you will only have 4 wires to take care of they are usually color coded like green with a black line and the other wire will be green showing that they are a pair to power one speaker.
If you have any questions just ask
Thanks again,
Luke
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Thanks in advance!
Also is it possible to leave the fader intact with aftermarket? I sort of like it.. Thanks!




The reason for the change in design philosophy is only limited power output can be achieved on a 12 volt supply. With a single ended amplifier the theoretical true RMS power is limited to about 4 watts (with a 4 ohm load) whereas with a bridged design, the theoretical true RMS power is limited to about 16 watts. Becker and the later Bose system were know to use very low impedance speakers (2 ohms or even 1.2 ohms) to try and over come these limitations.
Most stand alone car amplifiers go back to the singled ended design (because they also contain there own internal switching power supply the provides "rail" voltages well above 12 volts), but their increased power output will vaporize the fader in a matter of minutes.
- FD

But if you can’t, please just carefully tee splice into the existing wires without snipping off the factory plugs. That way it will be reversible.
Since your car is the type with the two piece radio and head unit, I would still suggest leaving all the factory wiring in place. You just need to run a few extra wires to make it work. To do this work, you’ll need to remove the wood center console panel at least. It’s probably easier to remove the whole center console.
All the needed power wires, antenna trigger wire, and the front speaker wires are still located up front. Once you hook those up, you just need to run wires to the rear speakers.
If you really want to keep the fader, you will need to repair your existing system or replace it with another old 2 channel one piece system like a 1480.
Last edited by alfajuj; Jan 3, 2014 at 04:43 AM.




