In Reply to: ammeter posted by joe in wilkinson on September 08, 2026 at 15:39:52:
Yes, it can operate plus or minus. It all has to do with the flow of current in the wire and which direction it is going. The original ammeter used induction where the wire feeds through the loop loosely (it is not clamped). New ammeters have the two posts to attach the wires onto. When the generator is not charging, engine not running, the current is flowing from the battery to the ignition system or lights if you have them. This causes the ammeter to show negative. When the engine is running and the generator is charging, the generator puts out more amperage than the tractor is using, either balancing out the usage or running current the opposite direction into the battery if the battery is low. This causes the ammeter to show 0 or positive.
When replacing the original with the new, you will need to either cut the wire and add terminals to the wires to attach to the ammeter, or disconnect the wire at the terminal block to attach it to the ammeter, then make a new wire from the ammeter to the terminal block.
If the ammeter shows backwards on the induction style, you just run the wire through the loop the other way. For the ammeter with posts, just swap the wires.