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So, I am working on an 87 928 with some slightly melted wire insulation in the Central Electric Panel.
My guess is that someone moved the panel to gain access to it without first disconnecting the battery ground strap.
None of the wires appeared to be burned in two.
None of the wires appeared to be melted to the point that the adjacent wires, though insulation that was melted did stick to the adjacent wires, did not seem to have the adjacent wires make electrical contact.
Some of the wires on the back of the electric panel did have insulation worn away, but they did not appear to be involved in the melting of insulation.
My assumption is that whoever did this, quickly noticed the spark / smoke and moved the panel back to a position that stopped whatever the short circuit was.
Here as some pictures;
This is probably the worst of it.
The electrical tape here is from somebody before me. There were probably some abraded wires that had 12v on them that shorted to the chassis when the panel was moved.
So the questions are, how bad is this?
The wires in the panel actually seem OK, just some melting of the insulation.
Ideally, all of the melted wires would be replaced... That would take a lot of time.
Can this be repaired by just taping the exposed areas?
Better than the tape job that is evident in the current pictures.
And this question seems pretty open ended, but what other components might have been damaged?
No short currently exists, Probably OK as long as nobody moves the panel with power to it.
Key on and Cranking currently cause no further smoke or damage.
The LH and EZK have been tested and do work.
The CPS signal looks good.
The fuel pump will run when the relay is grounded at pin 20 of the LH connector.
This is not my car...
At least 4 shops have worked on this car to troubleshoot a no start condition. I have had an ah ha moment and think I have the solution to this no start. But want to understand the condition of the Central Electric panel more.
I did find that the fuel pump fuse had been modified with solder to fatten up the blades so it would fit tighter at some point in the past.
When I looked at it, the fuse would not insert correctly and probably did not make good consistent contact.
I pulled the panel and removed the fuse block and fixed the internal contacts and inserted a new fuse.
I do not have the car local to me right now. I had been closer to where he lives and stopped by hoping it could be a quick fix. It wasn't quick on that day.
So, I am working on an 87 928 with some slightly melted wire insulation in the Central Electric Panel.
My guess is that someone moved the panel to gain access to it without first disconnecting the battery ground strap.
None of the wires appeared to be burned in two.
None of the wires appeared to be melted to the point that the adjacent wires, though insulation that was melted did stick to the adjacent wires, did not seem to have the adjacent wires make electrical contact.
Some of the wires on the back of the electric panel did have insulation worn away, but they did not appear to be involved in the melting of insulation.
My assumption is that whoever did this, quickly noticed the spark / smoke and moved the panel back to a position that stopped whatever the short circuit was.
Here as some pictures;
This is probably the worst of it.
The electrical tape here is from somebody before me. There were probably some abraded wires that had 12v on them that shorted to the chassis when the panel was moved.
So the questions are, how bad is this?
The wires in the panel actually seem OK, just some melting of the insulation.
Ideally, all of the melted wires would be replaced... That would take a lot of time.
Can this be repaired by just taping the exposed areas?
Better than the tape job that is evident in the current pictures.
And this question seems pretty open ended, but what other components might have been damaged?
No short currently exists, Probably OK as long as nobody moves the panel with power to it.
Key on and Cranking currently cause no further smoke or damage.
The LH and EZK have been tested and do work.
The CPS signal looks good.
The fuel pump will run when the relay is grounded at pin 20 of the LH connector.
This is not my car...
At least 4 shops have worked on this car to troubleshoot a no start condition. I have had an ah ha moment and think I have the solution to this no start. But want to understand the condition of the Central Electric panel more.
I did find that the fuel pump fuse had been modified with solder to fatten up the blades so it would fit tighter at some point in the past.
When I looked at it, the fuse would not insert correctly and probably did not make good consistent contact.
I pulled the panel and removed the fuse block and fixed the internal contacts and inserted a new fuse.
I do not have the car local to me right now. I had been closer to where he lives and stopped by hoping it could be a quick fix. It wasn't quick on that day.
It's worth hunting down a used '89 CE panel used/complete/intact, vs trying to replace individual conductors. You can buy the ends that poke through the panel if you want to tune up your wire crimping skills, of course.
The melting on the external wiring looks to be electrically-induced since there's no consistency in the melting that might suggest that it was caused by some external radiant source. It would be a good idea to list the wires with damage and their connections, then ID them and their routing to see where there's commonality.
Shop for a used panel on eBay, etc. I wonder if a PO was having electrical problems and solved them by putting in higher amp fuses until the wires heated up like a toaster.
So, I am working on an 87 928 with some slightly melted wire insulation in the Central Electric Panel....
Ken
'89 928 GT
Ken you may be master of understatement!
I also would suggest a used panel - however you also have some damage to the loom wires feeding the connectors at the CE panel too. Its important to inventory what crisped up so you know what equipment might be related to this - so then if you see oddball behavior in that equipment you have an idea why. The biggest risk is that you also have damage in the middle of the car looms in some hidden and relatively inaccessible place.
Any such damage could have been what initiated this mess or could be a results of it... but there is a risk that it is much worse than just this visible damage (which is already pretty bad).
It's worth hunting down a used '89 CE panel used/complete/intact, vs trying to replace individual conductors. You can buy the ends that poke through the panel if you want to tune up your wire crimping skills, of course.
The melting on the external wiring looks to be electrically-induced since there's no consistency in the melting that might suggest that it was caused by some external radiant source. It would be a good idea to list the wires with damage and their connections, then ID them and their routing to see where there's commonality.
Dr Bob, from what I observed of the panel, it looks to me like the wires on the back of the panel are abraded and when the panel was moved those hot wires probably contacted the chassis creating a local short circuit. I am not sure why the wires on the front of the panel show localized heat at the bends in the wires, unless that is a weak, stressed, higher resistance point.
I only have the picture right now, the panel is 4 hours away.
The wires that I think I have identified are for the
Wiper motor and switch,
Heated washers,
Alarm Control Unit,
Clock,
Glove box light,
rear hatch unlock switches at the drivers and passenger side.
The biggest risk is that you also have damage in the middle of the car looms in some hidden and relatively inaccessible place.
Any such damage could have been what initiated this mess or could be a results of it... but there is a risk that it is much worse than just this visible damage (which is already pretty bad).
Alan, I had mentioned to Barney before we looked for the burned wires, that I hoped it would only be one or two wires and not a mass of melted wires. One or two wires could be repaired pretty easily, a melted harness, not so much. I did not expect the back of the CE panel to look that way.
That said, I think all of the conductors, that I saw, are intact. I don't think the short that caused this was of long duration, probably just a split second by someone moving the panel with the battery connected.
Shop for a used panel on eBay, etc. I wonder if a PO was having electrical problems and solved them by putting in higher amp fuses until the wires heated up like a toaster.
Jon, There were electrical problems that shops were trying to diagnose. A failure to start condition. Why the whole electrical panel was loose to troubleshoot this ,I am not sure. I don't think it was due to higher amp fuses, I think a short from moving the panel.
Definitely trace the harnesses to see if there are any other crispy areas. On my 86 I had to replace the front harness in addition to the CE panel.
nosnow, I would hate to put in another CE panel and have another problem in the car smoke that one.
Ken - It's not likely that the wires on the backside of the panel chaffed against anything that would remove wire insulation and leading to short to ground. The panel being in place or even just laying roughly in position would not cause a problem either (as long as all the wire connections, including the stacked ground wires to the chassis were correct).
Alan is our resident expert on 928 electrical stuff, so I'd reread his post and seek a bit more guidance. The melting in both the rear panel wires and in the wires attached to the color-coded connectors along the lower portion of the panel seems to suggest a more "exotic" set of faults (simply meaning this isn't something we see often...if ever). I'm not sure throwing a new panel in will fix the problem - and you may witness the same melting of wire insulation.
This is likely to become a long-lived thread If you have the time, it will get sorted. It will take awhile.
1. Start by identifying what each melted wire feeds. (both behind the panel and at the colorful connectors.
2. Check the condition of the fuse sockets and connector pins just to eliminate the possibility oxidized degraded contacts were heating wires (a bit extreme to suspect these...but easy to check)
Then trace the wiring to search for more melting or sources of shorts. Mice come to mind.
Seems odd to have a remote high current draw (whatever the cause) without blowing the fuses. This is why I suggest looking at the condition of the fuse sockets. If the connections are degraded the fuses will get hot and melt plastic faceplate and fuse connector holders behind - HOWEVER the fuses will often not blow, they just heat up. A degraded contact adds resistance, and when it heats up the resistance rises exponentially, reducing current flowing through the fuse - and ironically prevents the fuse from blowing (indeed, little current may be flowing)
I posted a thread awhile ago about replacing fuse blocks and contacts that suffered the above. However, all the evidence of heat damage was limited to the fuse blocks. The wires and insulation were fine. Still, if you see contact and fuses in good condition and wire insulation melted all around...it begs the simple question - what can cause wires to heat until melting insulation and not effect the fuse sockets or blow fuses?
Last edited by Captain_Slow; 10-12-2017 at 06:52 AM.
I am making arrangements to get the car delivered to me to be able to diagnose it better.
Alan is our resident expert on 928 electrical stuff, so I'd reread his post and seek a bit more guidance. The melting in both the rear panel wires and in the wires attached to the color-coded connectors along the lower portion of the panel seems to suggest a more "exotic" set of faults (simply meaning this isn't something we see often...if ever). I'm not sure throwing a new panel in will fix the problem - and you may witness the same melting of wire insulation.
I have a fair degree of electrical background and am a little confused by the melting of the wire on the front side of the panel.
I may have to put Alan on sped dial then.
I have traced some the wires via the electrical diagram. Of the melted connectors, I may try to leave them disconnected initially to see what happens. Some were headlight washers, Seat adjustment controls, Clock power, rear hatch release. The problem one may the that alarm unit.
Seems odd to have a remote high current draw (whatever the cause) without blowing the fuses. This is why I suggest looking at the condition of the fuse sockets. If the connections are degraded the fuses will get hot and melt plastic faceplate and fuse connector holders behind - HOWEVER the fuses will often not blow, they just heat up. A degraded contact adds resistance, and when it heats up the resistance rises exponentially, reducing current flowing through the fuse - and ironically prevents the fuse from blowing (indeed, little current may be flowing)
There was oxidation on some of the fuses, when I was trying to clean up the fuse blades, the 25 amp fuses came apart in my hand.
When I get the car here I will clean the various fuses and contacts.
I agree fuses not blowing is odd. Maybe they did and were replaced before I saw it.
Or the short did not go through the fuses, ie. the panel was moved and caused the short via exposed 12v wires due to chaffing touching chassis ground. This is a guess at best.
Do you have a link to your thread about the fuse blocks? I did take one apart to tighten the fuse contacts for the fuel pump fuse.
I have a 1986 928 parts car. The CEP is intact. Is the early 86 the same as an 87?
'86 & '87 are radically different. It must be the exact same panel - in this case I think only '87 & '88 are the same (but check the CEP part numbers).
Given the damage and what you say about the equipment affected - I'd suggest its a more radical answer. I wonder if installing a battery in reverse could do that? The stock battery would be just about impossible to install that way - but I wonder about booster cables etc...
This is not a normal thing - something quite odd happened here...
I too don't buy any mechanical type explanation - a stock good/normal condition CE panel laying loose on a bare sheet of grounded steel would be perfectly safe IMO... its something "other"
10-10-2017, 05:22 PM
Central Electric Panel some melted insulation
If you have the time, it will get sorted. It will take awhile.