ELECTRICAL PROBLEM>>>HELP 72 c10

[Chevy Fan Always]

I keep frying voltage regulators. New harnesses, new alternator, all grounded. Ammeter does not move. Lights are strong but dim a little with increased rpm. Instructions on the regulator says do not polarize. Its not a delco but is for this truck. The first one started buzzing and then smoked, Any help Appreciated

[davepl]

Check the two fuses in the front corner of the engine wiring harness to see if the two little fuses are blown - not related to smoking the alternators but that might be why the ammeter does nothing.

If all the parts you are listing are new, then it's a tough one. Is it possible your regulator 4-pin connector somehow is on backwards?

[VetteVet]

Originally Posted by Chevy Fan Always

I keep frying voltage regulators. New harnesses, new alternator, all grounded. Ammeter does not move. Lights are strong but dim a little with increased rpm. Instructions on the regulator says do not polarize. Its not a delco but is for this truck. The first one started buzzing and then smoked, Any help Appreciated

Here's how the wiring looks.

Notice the ammeter wires with the fuses, shown on the bottom and the right of the diagram.



Do you have the regulator grounded to the sheet metal and to the alternator like it shows in the picture?

[Chevy Fan Always]

I think that ground wire to the alternator might be the culprit. Thanks very much. Those are nice diagrams.
Mike

[davepl]

In that diagram does the Ammeter work by simply comparing the voltages available at the B vs B/W little wires?

I also see the big block gets a bigger ground cable! Didn't know that.

[VetteVet]

Originally Posted by davepl

In that diagram does the Ammeter work by simply comparing the voltages available at the B vs B/W little wires?

I also see the big block gets a bigger ground cable! Didn't know that.

Yes Dave you are correct, The small wires use the connector wire between the battery junction on the right fender and the junction of the alternator, regulator and the power wire to the cab to read the voltage differential of the battery and the alternator.

This connector wire is known as the SHUNT between the two. It is the same as picturing a tug of war with the alternator on one end and the battery on the other. As long as they are equal the ammeter reads in the center or just to the C side. When the alternator quits then the battery is stronger so it will read discharge and when the battery is weaker the alternator will become the stronger and read on the C side.

A lot of people will install an internally regulated alternator and run the output wire directly to the battery or to the starter solenoid bypassing the SHUNT connector. and then they wonder why the ammeter doesn't work.

One-wire alternator users are famous for doing this.

[davepl]

Even though my other vehicle doesn't have an ammeter, I'm still rewiring the provided one-wire alternator in the accessory drive as a three-wire just because I think it's important for proper system charging.

It'd be even more important in our trucks where the run from the alternator to the battery is so long, I imagine.

Never had a one-wire alternator, hope to never have one!

[Chevy Fan Always]

Thanks for the help guys. The ground on the alternator was my bad. And when I checked the 4 amp fuses I really felt dumb. There were none. I guess I assumed new harnesses came with them. Heading out to get some, will let you know if the gauge works. As we always say " Don't assume, it always makes an ass out of you and me"

Mike

[davepl]

I forgot about that, it's weird but I don't think my harness came with fuses either! M&H should be including them if they're not, otherwise most people don't know to check.

[Chevy Fan Always]

Those are hard to find fuses, I got one 5 amp out of my old harness and found 3 and 5 amps. Ammeter sprang to life!