Hi,
My new 1983 240d is burning the #4 radio fuse as soon as the car turns on. It really cooks the fuse. Ive been able to get the radio to work when the car is off and just running on the battery. It is an aftermarket radio. The antenna doesn't move- could that force the fuse to blow? Any suggestions on where to begin?

Thanks very much!

The factory radio affects as many as 3 different fuses. See here for more info: Keeps blowing fuse. A little help?

It sounds like you've connected the switched wire to ground or it's loose and shorting something out since the fuse for that wire blows when you turn the ignition on.

I'm a fan of the Crutchfield adapter harness. It plugs into the factory radio jack (no cutting) and transfers the wires to modern industry standard (no guessing, just match the colors).

Search the media section, there's plenty of photos and wiring/fuse issues there.

The ashtray frame is electrically connected so a light comes on when the ashtray is opened
The PO of my 82 cobbed up an aftermarket radio and in my attempts to make sense of it I repeatedly blew the fuse whenever I connected to the terminal on the ashtray.

__________________
1981 240D 143k 4 spd manual -SOLD

2004 VW Jetta TDI 5 speed 300k -still driven daily

Just to be clear the aftermarket radio was installed by the previous owner. Not sure how they wired it...

I see the ashtray/lighter is on the same fuse as the radio. My ashtray seems to be missing a mounting frame of some sort. Its one of the wood faced ones. It just rests in its spot in the dash. No ashtray light, non functional cigarette outlet. It didn't occur to me that it may be causing the short by bumping the contacts. Apparently I need to figure out what if anything my ashtray is missing.

I'll try to post a photo shortly to show what I am describing.

Ok here are two photos of my ashtray. Im new at this, but it looks like it is missing a frame, or something to clip/slide into. Could the ashtray be hitting the two electrical contacts and causing a short? Any help would be really appreciated!

Attached Thumbnails

   

The ashtray is actually part of the circuit. Yes it snaps in and out but there are friction/snap electrical connectors on the frame and on the removable part itself. It is possible that the cigarette lighter is stuck down or corroded and is blowing the fuse.

As part of your next troubleshooting, just leave the ashtray out. It shouldn't affect the radio.

While you're in there - how are your console lights or instrument lights? Do any fuses blow when you turn on the headlights? That's another common mis-wire in the setup. If you're gonna fix it, find all the trouble now.

I'm not sure if you're missing the frame, but it's not connected correctly.

The ashtray should snap out and the frame is held in place by two screws. See that connector on the side? That ought to connect up to a harness, so you may have a loose harness that goes to fuse 4 in the console.

See if you can separate slide the ashtray away from the outside "shell."

Looking closer at the pics, I'm going to speculate - the PO didn't remove the retaining clips from the Becker. Those are the two metal things that stick down about 1/4 inch. In the OEM Becker they snap up unto the radio body. Your aftermarket radio doesn't have the same slots.

So....since the clips wouldn't retract, the ashtray frame doesn't fit right, so he didn't reinstall it correctly.

You need to remove your radio (hopefully it doesn't need any special tools to release any locks) then remove the OEM clips and look inside for the ashtray harness.

You'll need to source a few fine thread screws to remount the ashtray. I may be able to find out the size/thread count.

Thanks a ton!- that sure sounds like a good explanation to me. Wish I had a few more hours of daylight so I could give this a shot today.

Can the radio be turned on when the key is out of the ignition (off)? If so then the radio is not powered by Fuse #4 (F4) and you need to look at the other sources for the fault (cigar lighter seems to be the most likely culprit at this point). F4 is hot when in Accessory, Run or Start, but not when ignition is off. F4 also controls the glove box light, the passenger mirror and front heated seats if installed. The antenna motor control relay is powered by F4 through the original radio, but the antenna motor itself is powered by F2.

__________________
mjk

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

Just thought Id give a little update.

You were exactly right about those radio clips sticking down into the ashtray area! It took some effort, but I got the old radio out and removed the clips.

Im still not sure what exactly has been causing the radio to blow fuses though. I bought a new radio and I am going to redo the wiring using the new harness to see if that helps.

Any advice would be REALLY appreciated!

Also any suggestions on where to find two replacement screws for the ashtray frame?

Thanks!!

Nope. The only time I have been able to use the radio is when the key is in the ignition, but the car is off. When I startup the fuse is immediatley toasted.

To be a bit more precise: fuse 4 is blowing when you turn the car on. The radio may/may not have something to do with it. Unless you're unhappy with your current radio I'd troubleshoot the problem first then decide.

You've got the radio out - can you find the cigar lighter harness? If you shield that (or unplug it) does the fuse still blow?

What else is on that circuit? Check those items too.

If the PO cut the OEM wiring from the radio you'll have a small challenge ID'ing wires. Do you have a multimeter?

I'll check on screw size this weekend. Probably easiest to pick up something at a big box hardware store.

No worries, the old radio was so beat up I decided to replace it while I had it out. Im not really sure it was the problem though.

I did find the lighter harness, it was loose behind the radio. Only other item on the circuit that I know of is the glove compartment light. I don't have heated seats.

Here are some photos of what I have found...

Photo 1: Im assuming the speaker wires. There are 4 black wires coming out of one tube. The PO attached two wires from the harness to each of these 4 wires.

Photo 2: The remaining three wires attached to the harness. From what I have read, the brown on the right is the ground and the red is power. Not sure what the clear blue wire is.

Photo 3: Not sure what this is- but it was a lone loose wire behind the radio.


From what I have read, I need to bypass the fader for the rear speakers. I can't tell if this has already been done. Any thoughts? Both the radio I am taking out and putting in are Pioneers- the harnesses are almost identical.

Thanks!!


EDIT: Just realized there is one other item on fuse #4- "outside mirror"

Attached Thumbnails

     

Just to be clear do you mean to tape off the lighter harness? It has always been unplugged when the fuse blew. Maybe it was touching a wire?

Unfortunately I don't have a multimeter. I was hoping because I stuck with the same brand radio it would be pretty straightforward.

Thanks for all your help!!