[dmjlambert]

The purpose of the ammeter in the stock configuration is to tell you how much the battery is charging or discharging. The ammeter measures in which direction, and how much, current is moving between the battery and alternator.

"Normally" there would be discharging when running accessories without the engine running, because the current leaves the battery and goes through the 12 ga wire across the top of the radiator, past the connection where the alternator is connected, and on to the rest of the truck. And charging when the current leaves the alternator as the truck is running, and goes towards the battery to charge it, and also goes toward the cab to run various accessories. If you don't run accessories when the engine is off, then there will be just a little bit of charging for a little while after starting the truck, and then pretty much no current at all either direction along that wire that goes between the battery and alternator.

If your ammeter shows charging during normal truck use, it sounds like you may have connected accessories to the battery or to the terminal post over there by the battery.

In my opinion, it is best to
1. connect accessories that are a heavy draw directly to the alternator output or to the place where the alternator wire connects to the junction near the driver's side headlight where the big wires and the fused ammeter wire come together.
2. don't connect anything other than the battery, fused ammeter wire, and the wire that goes across the top of the radiator towards the alternator, at the passenger side fender terminal.
3. don't change the size of the 12 ga wire that goes across the top of the radiator between the battery and alternator. That wire functions as the ammeter shunt and is actually a part of the ammeter.
4. ensure you have a 6 to 9 inch 16 ga fusible link wire between the battery positive terminal and the passenger side fender terminal.
5. if you increase the load on the electric system, increase the ground wiring, too. There should be a ground terminal on the alternator and you can add a wire or increase the size of that wire to ground. Make it the same size as the wire running from the positive terminal of the alternator. 10 gauge should be damn near big enough for anything you want to run.