Does B+ in a flow chart mean that the voltage at the connector is the sames as at the battery?

Using a DVM measure voltage from oil pressure sender fuel pump switch connector Terminal A to ground.

Flow chart says: B+
Check for poor connection at fuel pump switch/engine oil pressure gauge sensor connector. If Ok replace sensor.

Voltage is positive 4.5 volts at the connector not 12.7 volts indicated at the battery. Should the voltage read the same at the connector as it does at the battery?