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I understand that this is not the thing to do routinely, more this is just a question to get my rear window defogger working reliably in the interim before undertaking a proper CE panel refresh in the future.
I have had some high resistance at the fuse holder for the rear window defogger, it hasn't caused a great deal of damage but the wire from the back of the fuse panel is obviously discoloured.
I can use contact cleaner and try and reduce the resistance of the joint, but could an alternative be to link the 12V feed (red) to the fuse output (grey) with an external fuse holder of the appropriate wire gauge and fuse rating?
Pull the fuses for the cooling engine cooling fans and the HVAC blower. All fuse connections have a bit of oxidation by now, but these fuses are the ones that experience high current - and will heat up. Resistance increases as the fuse contacts heat up...becoming a runaway heating effect if the draw is constant for an extended period. The fuse will not blow because the high resistance from oxidation and heating actually lowers the current flow to less than what will blow the fuse - yet the body of the fuse starts to melt. I did not see heating at the top of the panel as you have. You likely have very oxidized contacts. If your car ever had a leak form the blower box/air handler it is directly above the CE. If you see signs of melting and very crispy looking contacts in the holders - you need to replace the fuse block. If it's just a bit discolored I'd first try Deoxit 100 on ALL fuse holders in the panel. Your panels needs this at a minimum. My dash lights got brighter afterwards. Here's a link to the rebuild thread I did for a similar situation.
I have taken this apart and used contact cleaner and pinched the connections together again. Few more jobs to do then I will give it another go and see if the fuse heats up.
... Also, the discolored wire could be from high current draw and maybe you can troubleshoot if there is indeed a problem with the circuit.
No it is never that... this localized discoloration is heating from extra resistance in the the fuse holder - focus there.
What you propose on the external fuse holder could be an interim fix - but I don't really like it - they tend to become de-facto permanent fixes. Swapping in a donor replacement fuse holder block is the best fix if cleaning and snugging up the contacts doesn't work (ideally a block with the right fuse numbers - BUT CERTAINLY: with the right internal connections - test a replacement electrically as a match - these vary by year on the input bus shorting bars - do not skip this step - you can't tell by looking at it assembled).
Pull the fuses for the cooling engine cooling fans and the HVAC blower. All fuse connections have a bit of oxidation by now, but these fuses are the ones that experience high current - and will heat up. Resistance increases as the fuse contacts heat up...becoming a runaway heating effect if the draw is constant for an extended period. The fuse will not blow because the high resistance from oxidation and heating actually lowers the current flow to less than what will blow the fuse - yet the body of the fuse starts to melt. I did not see heating at the top of the panel as you have. You likely have very oxidized contacts. If your car ever had a leak form the blower box/air handler it is directly above the CE. If you see signs of melting and very crispy looking contacts in the holders - you need to replace the fuse block. If it's just a bit discolored I'd first try Deoxit 100 on ALL fuse holders in the panel. Your panels needs this at a minimum. My dash lights got brighter afterwards. Here's a link to the rebuild thread I did for a similar situation.
I've had this happen. I guess it's a Porsche thing. The fuse melts around the wire that's supposed to blow. This was a short, but when I got in there I had other heat damage. Contact 928 International for a spare board and use it for replacement parts for now and in the future.
I've had this happen. I guess it's a Porsche thing. The fuse melts around the wire that's supposed to blow. This was a short, but when I got in there I had other heat damage. Contact 928 International for a spare board and use it for replacement parts for now and in the future.
If the fuse was the correct value - then the cause is the same as this one - poor fuse contact. Folks have a very hard time believing this but it is not ever (EVER) an over current issue if the wire discoloration is localized near the fuse or if the fuse body melts - it is ALWAYS a fuse connection issue - circuit current will actually be below normal due to resistance build -up.
Ergo - the heat damage to wiring and fuse melting wasn't due to a short - it never will be (if the fuse value is correct with good quality fuses).
06-14-2020, 02:12 PM
Temporary CE Panel Fix
