Melted alternator wire....

[LSUfj]

The WL color wire on my 75 is melted, along with the white wire that goes to the amp meter. I've read up a bunch on this and found most of the answers I need. I am not sure I have the fusible link since the harness isnt in the best shape. Everything was working fine, but I pulled the instrument panel off for access and noticed this. I am planning to replace these two wires but wasnt sure of the gage??? Also, where is the fusible link? If I dont have one, I will add it. Questions:

1. What gage is the WL and W wire that go to the amp meter?
2. where is the fusible link on an early 75?
3. what size fuse should be used in the fusible link?

 

[Ming89FJ62]

The fusible link, if you have one, will be located between the + battery terminal and the wire harness. Originally it would have been attached to the + battery terminal, actually molded/soldered into the battery connection. The other side would have a plastic quick connect wire connector. There is no "fuse" in the fusible link - the wire itself is the fuse. Normally the wire is sized so that if too much current runs through it (think direct short) the wire will melt through acting as a fuse.

I'm not sure of the wire gauge. Some later models (like my 78's) have shunted amp gauges where the current is taped off the main power lead (everthing except the starter motor). Earlier models actually bring the main power through the amp gauge - which would require something like 10 ga.

You'll need a manual or wiring schematic to see what version you have.

Good luck

 

[CruisinGA]

Do you have anything other than a stock alternator?

Do you know what caused the current overload that melted the wire?

 

[bsmith123]

what year

what year is your rig the schematic will show if it should have the fusible link (sorry I missed it--a 75) ----ill have a look if i can find a 75 schematic

I think the ones that had the link also had a shunted ammeter with input fuses which should have prevented what you got there but best to be sure

Sorry no 75 schematic ---best thing then is to look for the extra wire going into the battery


Are you running any extra accessories like a winch and lights?

 

[LSUfj]

Do you have anything other than a stock alternator?

Do you know what caused the current overload that melted the wire?

I dont know what caused it. There have been a few times when it is difficult to start, which might have led to too much current for a sustained period.

I think the ones that had the link also had a shunted ammeter with input fuses which should have prevented what you got there but best to be sure

Sorry no 75 schematic ---best thing then is to look for the extra wire going into the battery


Are you running any extra accessories like a winch and lights?

Can you explain what you mean here about the shunted ammeter, maybe a pic..

I am not running any accessories. The WL wire is partially melted at the alternator and is almost without insulation at the meter. I am guessing that all of the power is going through the meter. Looks like a 10-12 ga wire.

Also, can a fusible link be replaced with a fuse? This is what I planned to do if the original link has been cut out.

Thanks again.
Bret

 

[Pin_Head]

All high current amp meters have shunts.

Later cruisers had an amp meter that used the fusible link as an "external" shunt. Earlier cruisers have a shunt build into the meter itself. With an external shunt, you don't have to carry the high current from the alternator into the cab through the meter. This is safer and cuts down on the length of large gauge, high current wire needed.

The most common reason the wire would melt like that is someone installed the battery backwards with the polarity reversed. If you had a fusible link, it would have melted first saving you from dealing with the mess.

 

[LSUfj]

I replaced the wire and found what looked like the original fusible link. It was in bad shape so I replaced it with a new 30 amp fusible link. The regulator looks to be connected but isnt using the original wire.

I got the wires replaced and was able to start it. The amp meter jumps to almost +30 amps. I cant get it to run long enough to check the voltage regulator. The carb needs adjustment so I might not be able to get it to run long enough to check the electrical system or adjust the carb. what to do....?

Anyway, what does the +30A at the meter mean? It sits very close to 0 when the key is in "on" but not running. Bad regulator or....?

Thanks.

 

[Pin_Head]

Anyway, what does the +30A at the meter mean? It sits very close to 0 when the key is in "on" but not running.

Thanks.

It means that your alternator is working and that the battery needs charging and it is charging. This is pretty normal for just after starting the engine although being that high might indicate that you had to crank it a lot to get it started. It should read 0 with the key off and when the battery is fully charged and the alternator is working (normal running state).

 

[bsmith123]

ammeter

"Can you explain what you mean here about the shunted ammeter, maybe a pic.."

Sorry just got back from the Docs

just means the current flowing through is split so not all of it flows through the meter

read all about it


http://www.allaboutcircuits.com/vol_1/chpt_8/4.html

Where the damage is the worst for a short is usually the place where it happened so you may have just chafed through on the wire behind the dash

should be simple enough and not expensive to fix