Wiring question

[R.O.B.]

If you look at "A", what does that wire do? And what size fuse should it use? (mines missing)



Same for "B", what does it do and what size fuse should it use? (again, fuse missing)



And last but not least, can I just connect wire A into the same place where wire B connects, inline from the alternator to the battery? This would help clean up the wire mess that I have.



Thanks,

Rob

[kwmech]

They are sensing wires for the AMP gauge. You could eliminate and convert to a volt meter to monitor your charging system

[Stocker]

IIRC, the ammeter gauge takes 4amp fuses, about 5/8" long. They can be hard to find. I found some 5amp fuses at Napa, in a box with #782-1035 printed on it (maybe the wrong box?).
The fuses are stamped BUSS AGA-5A and the gauge is working just fine with them.

[RustyPile]

Both wires lead to the ammeter located in the instrument cluster. The meter circuit is a shunt circuit so it's not actually an integral part of the charging circuit, just an indicator of charging/discharging function. This circuit is found only with the gauge and is absent with the charge idiot light.. Replace both fuses (3 - 4 amp each) and your ammeter should start working..

[R.O.B.]

Thanks guys, so I can probably wire them together and be ok.

Since they both come off the battery area, I wonder why there's 2 wires.

[Accelo]

The meter is a milli-vollt gauge not an amperage gauge like it is labeled.
Both side for the Amp gauge are positive.
Don't wire them without a fuse. The circuit would not have any protection if you do.
Cheers

[pjmoreland]

Originally Posted by R.O.B.

Thanks guys, so I can probably wire them together and be ok.

Since they both come off the battery area, I wonder why there's 2 wires.

Your battery ammeter gauge will not work if you attach those two A and B wires to the same point. They must be attached to opposite ends of the red 12 gauge wire that connects the battery to the main splice where the alternator ties in. The gauge relies on the resistance of that long length (5-6 feet?) of the red wire to function correctly.

[MikeB]

I just have to say that I'm happy to read the above responses. Over the years I have heard several folks (even one at a wiring harness company) say our trucks used a full current ammeter, and even argue the point!

[kwmech]

Originally Posted by MikeB

I just have to say that I'm happy to read the above responses. Over the years I have heard several folks (even one at a wiring harness company) say our trucks used a full current ammeter, and even argue the point!

That would have surely blown the fuses and worse fried the harness

[franken]

Originally Posted by R.O.B.

Thanks guys, so I can probably wire them together and be ok.

Since they both come off the battery area, I wonder why there's 2 wires.

Don't tie them together.
Think of it like this. One point is closer to the battery, and the other to the alternator. The (as labelled) battery gauge reads the difference in the two voltages. If the alt is charging, the gauge will read charge because alt voltage is higher than battery voltage.

To change the subject, not the fusible link in the diagram above and to the right of the battery. Make sure you have one, since without it a short can cause the harness to fry.

[pontiacvince]

Originally Posted by kwmech

They are sensing wires for the AMP gauge. You could eliminate and convert to a volt meter to monitor your charging system

I had my gauge cluster rebuilt and I had the Amp gauge replaced with a Volt meter. Everything seems to be working except the new Volt meter...any ideas?

[franken]

It's sort of bad form to hijack a thread, particularly when the subject is different.
A voltmeter would want one side 12V and the other grounded.

[68 P.O.S.]

You're fine man. Check out this thread: http://67-72chevytrucks.com/vboard/s...d.php?t=630289