Hi Guys,
What would be the cause of a melted alternator wiring harness. I have a few spares alternators which came from different buses and they all have the same hot spots. The grey plastic harness cover is blackened. One spot right were the harness come out of the alternator and the other were it make a sharp bent through the grommet.
The brown wire (D-) and the larger red (B+) show signs of melting.
Could it be from running a really dead battery and then a excessive charging current (40amps) from the aternator is causing the large red (B+) wire to melt? but why the brown wire(D-)
Or
Could it be a short circuit which is unfused and causing large current to flow through the alternator wiring harness and melting it?
I don't have appliance running, no fridge, heater...... I did replace the headlights with some H4 .
Any help is appriciated,
Thanks!
Phil
melted alternator harness
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busman78
- Posts: 625
- Joined: Thu Feb 13, 2003 12:01 am
It is called rubber staining from the grommet. A quick check with an ohm meter will confirm the wires are still intact. The ends of the wires that were attached to the altenator have the darkening effect, that is from age, plastic is good, but the back of the altenator gets warm and over time plastic degrades.
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orangebus
- Posts: 8
- Joined: Wed Sep 03, 2003 9:59 am
Thanks for the reply Busman 78,
The grommet deterioration theory makes alot of sense, because the wires are not melted in that area.But I still don't under stand why the brown(D-) and the Red(B+) are melted. I have three harness with the same more or less melt on those two wires. Are these wire under rated to be the sacrificial link??
I'm trying to get to the bottom of this to make the appropiate fix for when I make the new harness.(larger wires, fuses, fixing short circuit and checking current draws.........)
Cheers!
Phil
The grommet deterioration theory makes alot of sense, because the wires are not melted in that area.But I still don't under stand why the brown(D-) and the Red(B+) are melted. I have three harness with the same more or less melt on those two wires. Are these wire under rated to be the sacrificial link??
I'm trying to get to the bottom of this to make the appropiate fix for when I make the new harness.(larger wires, fuses, fixing short circuit and checking current draws.........)
Cheers!
Phil
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busman78
- Posts: 625
- Joined: Thu Feb 13, 2003 12:01 am
Are they melted at the ends? or midway?
Melted ends are an indication of a problem where those ends attached, too much current. A midway meltdown is a short between the output and termination, hense the melting in the middle.
Either way you can install fused link, just a simple 40 amp inline circuit breaker. Really, at no time should you be drawing 100%.
Do your H-4's have circuit protection?
Melted ends are an indication of a problem where those ends attached, too much current. A midway meltdown is a short between the output and termination, hense the melting in the middle.
Either way you can install fused link, just a simple 40 amp inline circuit breaker. Really, at no time should you be drawing 100%.
Do your H-4's have circuit protection?