The oil pressure switch is used to excite the alternator.Posco wrote:Can anyone explain to to me what these electrical wire are coming off the tee on my oil pressure gauge? It has two wires, one leading to a terminal on the alternator and the other leading to the starter switch (cranking motor).
Oil pressure comes up, closes switch, voltage applied to alternator terminal #1 in the earlier posted diagram. Voltage excites the alternator, starts the alternator charging.
Shut off engine, oil pressure drops, switch opens, disconnects from alternator.