How do I fix this? Blown "fuse mount" melted and inoperable (pic included)
 

I had a faulty pin connector on the back of my instrument cluster. Which caused this fuse to continually blow and I guess it also must have started a tiny electrical fire in the fuse box. Because now it's all melted and was covered in the white electrical fire type corrosion. see picture (I had already wire brushed a lot of the corrosion off when I took the pic, the fuse mount was completely covered in the white stuff at first

Now it is completely not working. I wire brushed all the corrosion and put a new fuse in. And it doesn't blow but it also does not allow everything associated with that fuse to work.


Do I need to unmounted the fuse box, push it into the dash and replace the "fuse mount"? Or would you guys suspect that I need to cut, strip and re-crimp the wire and connector that is associated with that fuse on the back of the fuse box?


Is this what needs to be done?


Does anyone know an easier way to do this? I really would not enjoy working on electrical all crammed up on the floor of my driver's seat to reach up behind the dash and squeeze my hands in there to replace the broken parts. is there a trick to getting to the back of the fuse box from the top end (engine compartment)?


I fixed the grounded out connector in the cluster that was causing this. So the root of the problem has been fixed btw

The "right" way to fix it is to find a donor fuse box and swap over the contacts, once burned like that, you'll have repeated problems.

The next best way to fix it is to get an in-line fuseholder and tie it into the wiring outside the fuse box. Make sure to label your fusebox legend if you do that.

You can try to salvage what's there by getting the metal off. You'll need to use some carbide sandpaper and some elbow grease. If you can't get it down to bare metal, you'll have to do something else.

While you're in there, replace ALL of those crappy aluminum fuses. They cause LOTS of problems.

x2 on this, use good copper and ceramic fuses, not the aluminum and plastic cheapies. I had an old VW years ago that gave me a number of weird electrical problems. All was solved by replacing the aluminum fuses with copper ones.

ya i think im gonna go with the "next best way" method haha. I assume everyone understands how much of a pain in the ass electrics are, haha no one likes working on an electrical issue. Especially one crammed in the top corner of the dash!!! blaahh


this is on my strictly utilitarian 300d that i use to drive to work and back, so im willing to do a few jerry rigs here and there. I do concrete so as you could imagine its pretty dirty and rough around the edges. but i do keep the engine in tip top shape the best i can. If this issue was in my nice w123 id fix it 100% right

The fuse controls the background lights in the cluster as well as my passenger side front and back standing lights. In this car i dont care about the background lights in the cluster but i really dont like getting pulled over at 5AM on my way to work because my tail light is out.


alright thanks for the help

ok im willing to do this. and i will. about 5 of the fuses in there are the copper ones already. so ill just finish the job and swap out the rest.


on a side bar...
Am I the only one that has the hardest time in the world trying to put the fuse box cover back on??? I have found "the trick" to get it back on there. But mannnn ive spent a half hour trying to get that darn cover back on in the past!!

I pulled a fuse box from my 85SD parts car which is the same box as the 84SD with 1 broken tab on 1 fuse. All of the wires have round terminals through which screws are inserted and then screwed to the fuse box. As an example, fuse 2 has 2 sets of wires attached, one screw is at the top and another attaches to the bottom.

The process of replacing the box is fairly straight forward if you do a good job of keeping the sets of wires together and label them correctly. I was going to begin at the top and number each connection consecutively from 1 - n. Wires would be taped together and marked to match the connection. I'd make a diagram, take pics and finish the project the same day it was started to avoid forgetting how it goes back together. I don't expect that simply replacing the box would take long.

You should tell us the year of your 300D. When the #8 fuseholder in my 1985 CA 300D melted the plastic, I soldered-in a fuse-holder for a U.S. style blade fuse (post 2). It has thick yellow wire, the largest one Autozone had. I forgot the rating (20A?). It barely fits under the cover. That fuse is for the blower, and often melts the holder. I also found installing the fuse cover tricky, but can do in 10 sec now. Slide the weatherstrip off the cowl for an extra 1" room. You slide it in oriented just-so (forgot, bottom first & tilted?). I 3rd switching to gold-plated fuses instead of the factory tin-plated ones. With later, you will need to keep removing and sanding the tips to keep your windows and sun-roof working. Even coating w/ dielectric grease didn't help. I bought gold w/ ceramic body from an e-bay seller linked here, in blocks ~20 qty at much better price than auto parts.

Later, I was getting a voltage drop there, pulled down the fuse-box to the cabin floor (removed several boxes for room), and found the drop was across a crimped connection under the #8. Cleaned and soldered that junction, and blower worked again. I posted w/ photos. Others posted that I was crazy - either there is no such crimp (my photo faked?) or there would be no such drop (my multimeter lied?). I generally ignore such unschooled chatter. Later, I looked at my 1984 300D and didn't see that crimp, so perhaps a 1985-specific issue. In both cars, I ran a wire thru the grommet behind the battery (w/ in-line fuse) to power a relay, and rewired so the blower relay box is powered via the relay, not the #8 fuse. Good luck.

I'm rolling the 1980 300d non turbo...


What I'm trying to get at by me saying this is a "hard job" is strictly because of the location of the back side of the fuse box. The location which I will have to be unscrewing, cutting, crimping wires and etc, not to mention that I can't let anything get get mixed up.

So now my question is... What is the easiest way to do this? How can I get more access to the fuse. Is from inside the car?

The post above me, BillGrisom, said he was able to drop the box and wires all the way down to the floor. How did you pull this off? At first tinkering it seemed to me that the wires and grounds especially weren't long enough to allow me to pull the box to the floor?


Can you try to explain to me how you did that, in more detail please Bill

Thanks guys

I would not replace the fuse box unless you know what you are doing. I would clean the area, solder 2 wires out and add another fuse to it. Use something like the modern car or a standalone fuse like inline fuse. Too many things can go wrong when replacing the fuse box. It is obviously the best solution.

Agree. It's not that big a deal to bypass the fusebox.

Sure, use google to search for my post, adding PeachParts to the search.
I don't recall that the fuse-box made it all the way to the floor, maybe 2" short, but certainly enough room to easily work on it. Put something down so you don't burn your carpet and don't set the car on fire soldering. My alarm box was already gone since it kept going off and I didn't understand it. There is a cruise control box in the way, and I recall another box. I needed a 1/4 socket w/ extension to get off one bracket screw. But, if doing as many suggested, and just soldering-in an in-line fuse-holder, you can do that from up top w/ fuse-box in-place.