Correct - from the radio up to the console switch

And regarding wire color codes - they vary based on year. I've got schematics for different years and some have the blue/red antenna wire and some have a black antenna wire. I think the only no kidding constant is that brown is ground. Trust but verify.

Thanks! I made some progress today. I snipped the wires behind the fader, found the four pairs of speaker wires and fed them back to the radio hole.

I also traced the black wire in the 3rd photo back up to the antenna switch (just as you had figured) and traced the clear blue wire back to the + terminal on the battery. Now things are starting to look a lot cleaner than they did and I have all the wires identified...I think! At that point it was getting dark, so i'll have to finish up tomorrow.

It looks like on my 240d:

brown= ground
clear blue= constant power
red= switched power
black= antenna control (which I will cap, the radio harness has no spot for it)

Red speaker wire= left front
green speaker wire=right front
red/black speaker wire=left rear
green/black speaker wire=right rear

No way I would have had any clue without the help from here! Hopefully cleaning things up will correct the short.
Thanks for all the guidance!

Not sure why you have constant power direct from the battery. There should be red wire under the dash that has constant power that is not connected to anything except fuse 2. It's worth looking for if only to eliminate the unfused wire to the battery, that's a bit of a fire hazard.

__________________
mjk

'84 300SD 119KMi (Liesl der Diesel)
'84 300D 326KMi when the oil left (former parts car)
'82 300SD 253KMi (new parts car)

Really appreciate you mentioning that. I figured it was added because my 240d didn't have one originally. (?) I'll go do some more digging, but it seemed like that is what I have to work with.

I do have a red wire, but I was under the impression that was the switched power.

I really need to go get a multimeter and cut out the guesswork. If I can't find another constant power wire.. would adding an inline fuse to the wire from the battery be a good idea? Definitely looking to do this safely!

Thanks a lot!

You could add a fuse, would be best close to the battery inside the engine compartment. Alternatively, you could try to connect a wire to the fuse box, but doing it properly would require getting under the fuse box and making a connection there. You could also cut into a wire making sure you know which circuit you're cutting into and connect the wires using a crimp terminal. Just make sure the battery is disconnected before playing with any wires in the fuse box.

__________________
mjk

'84 300SD 119KMi (Liesl der Diesel)
'84 300D 326KMi when the oil left (former parts car)
'82 300SD 253KMi (new parts car)

X 2 on the getting a multimeter and eliminating guesswork.

One more thing to consider when talking about the apparently non-OEM constant power and the unplugged/disconnected cig lighter: do you plan on running/charging any other gizmos off the lighter?

If so, take the time to figure out the best way. I've seen posts where guys added an extra charging port off the console so the iPod/phone/GPS etc sat in the spot under the arm rest or on the pax seat.

A heavy gauge weather-capped inline fuse holder is cheap. If that blue wire goes through the firewall direct to the battery, I'd protect it -- and your car -- with a fuse close to the terminal.

I did some more poking around- I couldn't find anything else that looked like a constant power line. Looking through old threads here and at benzworld, it seems others have had the same issue and wired constant power from the clock, hazards or battery. Maybe certain years/ models had no extra constant power wire?

I'm hoping to put the ashtray back in correctly, reconnect the ashtray harness and use the lighter as a charger. I'll post a photo just to confirm the ashtray wiring looks the way it should. From what I can tell the harness is original, up until the connection for the radio.

I am missing the two screws that hold the ashtray frame. Any idea of the size? Haven't been able to find that info anywhere.

The only loose/disconnected wire I'll have left would be the black antenna wire, which I have capped.

I'll go pick up a multimeter and a good quality inline fuse this morning. Thanks helping me do this the right way!

Probably getting too complicated, but would it be possible to take out the fader dial and put in a charging port? That would be cool.

search fader and you'll find other posts who have done that

Ok..I dug farther back and found one more black plug! It has a Mercedes symbol on it. Maybe the original radio plug? Not sure.

Photo 1 is of the black plug. Going back a bit, it originates from the same sleeve as the ashtray wire.

Photo 2 shows what I think is the white ashtray plug on the left. From the ashtray plug the sleeve goes back up to the radio hole.

Photo 3 this is the end coming out of the radio hole. I believe the brown is ground and the red is the switched ignition.

Im so new at this its hard for me to tell what is original and what is not. If the black plug is the original radio plug, should I use that instead?

As always, Thanks for ANY help!

Attached Thumbnails

     

picture #2 is deff ashtray plug
cant help w/ other plugs as all mine were cut except ashtray

It looks like in post 14 the spade clip I think connects to the back of the radio near the power. I think that is for the power antenna, if you pull the cover back on that wire it should be blue under it. Or at least mine was.

Thanks!- is it normal for the ashtray plug to have a set of wires going back up to the radio? I can't tell if that was added on.

I think that is factory setup. My 85 is like that.
Somehow I think the radio grounds are connected into the ashtray via that plug and the ashtray frame

which radio are you installing?

Im swapping a pioneer for a pioneer. Just a cheap simple one that has an aux input. Unfortunately the old one wasn't wired correctly, so I am trying to straighten things out as best I can, before I put the new one in.

I took out an aftermarket that kept draining the battery, and would not shut off even w/ the face removed. Put back in a factory one and it works fine. Search "fader" and you shoud find some good articles on aftermarket radios