Charging system road rage
With the car off or on doesn't make a difference when messing with those connection. The battery must be disconnected before putting anything metal near them. A wrench or a wedding ring on your finger, doesn't matter. Those wires are always hot as long as the battery is connected.
So if the battery is at 12.5 Volts, every wire up to the key switch, headlight switch, and brake light switch is 12.5 Volts.
The meter that is marked 40 to 40 in your car is an ammeter. It shows current flowing to or from the battery.
When the alternator is running, current will flow through the ammeter until the battery is recharged. Then it will show zero.
The positive field wire gets power when the key is in run.
That's good they were tight.
With the car off or on doesn't make a difference when messing with those connection. The battery must be disconnected before putting anything metal near them. A wrench or a wedding ring on your finger, doesn't matter. Those wires are always hot as long as the battery is connected.
So if the battery is at 12.5 Volts, every wire up to the key switch, headlight switch, and brake light switch is 12.5 Volts.
The meter that is marked 40 to 40 in your car is an ammeter. It shows current flowing to or from the battery.
When the alternator is running, current will flow through the ammeter until the battery is recharged. Then it will show zero.
The positive field wire gets power when the key is in run.