Fusible link trouble

[Duster_71]

The ammeter is in the battery feed.
When the battery is connected all of the main wires are at battery potential.
View attachment 1715355864

Danger , Danger! Will Rogers

Headed to a scenario like the second example here:
Fusible Links in Charging Systems with Ammeter

Find where/what connects that lead to ground. Then it should be good.

Thanks Mattax,
In example 2 from your link it shows internal short at alternator, would the vehicle have to be running for that to cause the fusible link to burn? Is there a simple way to check the field terminals to the main power out or alternator body to determine if it is internally shorted out?

 

[Mattax]

You're missing the fundementals of a circuit and therefore how to make use of the test equipment.

Let's start with this:

Is there a simple way to check the field terminals to the main power out or alternator body to determine if it is internally shorted out?

The field terminals never connect to the output. They are the connections to the rotor's slip rings via carbon brushes. Power through the rotor is regulated. Look at these photos and description which should help you understand how an alternator works. Charging system question

In example 2 from your link it shows internal short at alternator, would the vehicle have to be running for that to cause the fusible link to burn?

Let's go back to this drawing and some critical concepts.

If the battery positive post is 12.5 Volts above the negative post, what is the voltage at the alternator output stud?
How much current is flowing to the output stud?

If it helps, lets remove the starter and install a test light.

 

[Mattax]

Current is electrons moving.
When a circuit is open, electricity can not return to ground.
When a circuit is closed, electrons can flow. The amount flowing is measured in Amperes. This is similar to quantifying liquid or air flow in gallons per minute.

The amount of electicity flowing through a circuit is generally determined by the resistance of the devices, and the voltage the electricity is being supplied at.

When there is a short to ground, there is little to no resistance, and the current flow is going to be very high.

If there is a test light in the path of flow, it will provide the regulation - which is why someone earlier mentioned it as a testing method.

If you are going to use continuity or resistance for trouble shooting, then with the battery disconnected, systematically look for continuity (or low resistance) to ground.


So lets say supply wire to the ignition switch connector has been pinched against some metal.
With the battery hooked up, the flow path would look like this.

Notice the ammeter reading?
What's happening at the fusible link?

Installing a lamp into the flow path,

Notice the ammeter reading?

Using an Ohmeter, the same problem is identified like this. Right?

When you disconnected the wires at the ammeter, you began the process of narrowing down where the ground connection is located.
Make sense?

 

[Duster_71]

Current is electrons moving.
When a circuit is open, electricity can not return to ground.
When a circuit is closed, electrons can flow. The amount flowing is measured in Amperes. This is similar to quantifying liquid or air flow in gallons per minute.

The amount of electicity flowing through a circuit is generally determined by the resistance of the devices, and the voltage the electricity is being supplied at.

When there is a short to ground, there is little to no resistance, and the current flow is going to be very high.

If there is a test light in the path of flow, it will provide the regulation - which is why someone earlier mentioned it as a testing method.

If you are going to use continuity or resistance for trouble shooting, then with the battery disconnected, systematically look for continuity (or low resistance) to ground.


So lets say supply wire to the ignition switch connector has been pinched against some metal.
With the battery hooked up, the flow path would look like this.
View attachment 1715358279
Notice the ammeter reading?
What's happening at the fusible link?

Installing a lamp into the flow path,
View attachment 1715358280
Notice the ammeter reading?

Using an Ohmeter, the same problem is identified like this. Right?
View attachment 1715358304

When you disconnected the wires at the ammeter, you began the process of narrowing down where the ground connection is located.
Make sense?

Thanks Mattax, I appreciate your assistance and patience, my knowledge and experience is very limited. I did some test light checks at the bulkhead and came up with the following: I hit each male and female connector on the center connector (disconnected) slots J to R, J male no light, J female-bright light, K male-bright lite, K female-dim light, L male-no light, L female-no light, M male-no light, M female-dim light, N male-bright light, N female-bright light, P male-no light, P female-bright light, Q male-bright light, Q female-no light, R male-no light, R female connector-dim light.
Additionally, I used the test light at various connections under the dash to include the positive side of the ammeter and everything lit like a x-mas tree. Is there any useful information to be had from the from my reading at the bulk head or am I just spinning my wheels?