It does sound like your wiring is reversed.... but!!!
It may also be you have a bad neutral. The 4 volts should be zero. It indicates you have higher than normal resistance on that wire. This could happen from bad screw connections or bad twist-on connector.
When you finish reversing, check again. If still 4 volts, chase that down.
It may also be you have a bad neutral. The 4 volts should be zero. It indicates you have higher than normal resistance on that wire. This could happen from bad screw connections or bad twist-on connector.
When you finish reversing, check again. If still 4 volts, chase that down.