No Crack - Melted Fuse

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gte619n
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Joined: Wed Aug 05, 2015 8:30 pm
Location: Atlanta, GA

No Crack - Melted Fuse

Post by gte619n »

Hey guys,

I hoping you could help me diagnose a little whoopsie that seems to have happened. I drove the car around and was going to swap in a different BMW C43 headunit to replace the sketchy volume control. Got everything plugged up working and then attempted to start the car. All the lights and such turn on, but no action on the starter. I think, "oh I must have popped a fuse," and low and behold:

Image
Image

Uh oh. That ain't good...

So everything seems to work in the cabin with the exception of the head unit and then, of course, the starter. I removed the head unit and then replaced the fuse, but still no crank.

What the heck in the world happened here? Any tips on how to chase this down?
Evan Ruff, Atlanta GA, Engineer
1970 Ford F100
1972 BMW 3.0CSi, L-Jet 3.5L
1978 Ferrari 308GTB
1985 BMW M635CSi
2016 BMW M2
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olympia57
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Joined: Thu Sep 13, 2012 1:47 pm
Location: Ireland

Re: No Crack - Melted Fuse

Post by olympia57 »

First thing I'd do is detach the fuse holder tray from the case and examine the wiring on the underside of the fuse holders . These are all soldered joints and I experienced a fault condition on a lighting circuit that took a long while to trace to a poor soldered joint in that very area . It's possibly been caused by a similar issue or alternatively a poor, high resistance connection on the live spade of the fuse holder , hence it not blowing initially .
I usually remove , check and clean the spades and then refit once a year on my vehicles . It only takes a few minutes.
Only this week I had a no brake light fault on another vehicle , I removed the fuse checked and cleaned it and all was well again .
Go from there .

I think you were lucky there ........ Good luck .
Don
1981 635 series 1
gte619n
Posts: 128
Joined: Wed Aug 05, 2015 8:30 pm
Location: Atlanta, GA

Re: No Crack - Melted Fuse

Post by gte619n »

Oh nice! I didn't know it was a split box. Will do and report back.
Evan Ruff, Atlanta GA, Engineer
1970 Ford F100
1972 BMW 3.0CSi, L-Jet 3.5L
1978 Ferrari 308GTB
1985 BMW M635CSi
2016 BMW M2
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olympia57
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Location: Ireland

Re: No Crack - Melted Fuse

Post by olympia57 »

gte619n wrote: Sat Jan 08, 2022 9:07 pm Oh nice! I didn't know it was a split box. Will do and report back.
Looking back at some old photos I was wrong in saying that the case splits .... :oops:
If you detach it from it's mounting to the inner wing and invert it you will expose the soldered joints I speak off.
Don
1981 635 series 1
wattsmonkey
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Re: No Crack - Melted Fuse

Post by wattsmonkey »

olympia57 wrote: Sun Jan 09, 2022 12:35 pm
gte619n wrote: Sat Jan 08, 2022 9:07 pm Oh nice! I didn't know it was a split box. Will do and report back.
Looking back at some old photos I was wrong in saying that the case splits .... :oops:
If you detach it from it's mounting to the inner wing and invert it you will expose the soldered joints I speak off.
Don
You're right with the Series 2 box, Don - that splits as you say.
"Most of it necessary; all of it enjoyable." LJKS
'84 635CSi, dogleg...itbs and supercharger????? Eaton Mess
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olympia57
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Re: No Crack - Melted Fuse

Post by olympia57 »

:-k
Nine years since I did that particular "fault find " Rob . It was that little part of the memory jigsaw that was missing ........Thanks.
1981 635 series 1
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