Fuse Block hidden problem
 

I recently purchased a complete wiring harness to use as an organ donor for a project on my ‘87 3.2. As I disassembled the harness into its 20ish sub-harnesses I found some significant issues hiding in the fuse blocks.
The photo with the yellow fuse shows a wire that likely was over inserted at the factory. Note the ferrule isn’t crimped and the screw head isn’t bunged up. Likely not a high current circuit as the connection isn’t burnt.
The photo with the red/green wire and two cooked terminals drills down to a fairly serious issue that isn’t readily apparent without removing the wires and getting curious. Note the shinier of the two screws has a damaged slot likely from repeatedly trying to tighten the connection to fix the buried problem. Both terminal/fuse holders have loose rivets that hold the assembly together. I found this by tightening the screws then gently backing them off. The terminal on both connections turned very freely a few degrees before the screw loosened. Over time the loose rivet connection heated and discolored the fuse holder. Loose rivets! Anyone seen this?
The photo with the corroded connections is typical of many we see while troubleshooting. The badly stripped red wire has begun melting due to the heat generated by the lack of strands.
When you encounter a badly heated fuse holder it likely has lost its spring tension due to heat annealing the temper out of the metal component. I’m going to guess either phosphorus or beryllium is alloyed here to promote electrical and mechanical design requirements.
http://forums.pelicanparts.com/uploa...1635612602.jpg
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Missing pic
 

Yep, that’s why we redesigned the fuse panel. Often the riveting fails, hidden on the back of the blocks. It’s not just the lack of spring tension that causes the fuses and wiring to heat.

Other than the factory guy missing on the ferrule insertion for the fog light wire after his lunch time beer…
Pretty typical and common failures of the type of fuse panels used by Porsche…
That is why Johnny and others make replacement fuse panels that are available from Pelican.

I installed the Adapt Motorsport bladed fuse panel which has larger wire terminals than OEM so there are no crowding issues.

http://forums.pelicanparts.com/porsche-911-technical-forum/1103755-adapt-motorsports-mini-blade-fuse-panel-g-bodies-review.html#post11479958

While you are at it you should solder the rivets on the back of the panel that tie circuits together. Jonny hinted at it.

What happens is the rivet will start to corrode. May not even be noticeable, but will create some resistance and then heat. I had a block burn up when that happened to me. Just take a good solder gun and run a bead of solder over the rivet.

You will be surprised how much resistance there is on the fuse block where the fuses connect. With the car running take a digital volt meter and touch it to both sides of a fuse. I was getting .5 volts on some fuses. Not good. Same technique can be used on light sockets or ground connections. You would be surprised at how much resistance may be hiding in one of these old cars.

Tea,
I understand your concern. A few years ago I had a 3.6 conversion installed and was working toward updating various parts of the SC (78). I was installing a new radio, alarm and moving the battery to the smugglers box and when I went to replace a few fuses and in noticed the plastic behind the terminals were cracked and some just broke off.

In my opinion those bullet fuses and the original fuse box is problematic. Probably pretty good option back then, but with alternative fuse type options, I suggest considering an upgrade for many years of trouble free electical.

The Adapt Motorsports panel or other ready made panels weren't available at the time so I made my own using the sheet metal from the original fuse panel, welding an extension for the JW headlight relay and mini ATO fuse terminals. I think I found the info somewhere on this forum that gave me the idea to do it.

http://forums.pelicanparts.com/uploa...1636218294.jpg

The advantage of the Adapt and other ready made panels is you can use the wires and ferrels (assuming they are in good condition) as is. I had to cut, strip and crimp new connections and in some cases make extensions to attach the existing wires to my home made panel. But at least I know the new connections are to fresh bare wire.

The advantage of the Adapt and other ready made panels is you can use the wires and ferrels (assuming they are in good condition) as is. I had to cut, strip and crimp new connections and in some cases make extensions to attach the existing wires to my home made panel. But at least I know the new connections are to fresh bare wire.

From my experience, just ensure you accurately label the the wires and don't leave a long time gap from when you label to when you finish the work as the labels may come off and then :confused:

Good luck with the project.

Pitsqrd