Re: 140hp Mariner brand new alarms out.
WoyWoy, that sensor has two leads. One goes to ground on the engine block and the second lead goes to the lube alert module. With oil in the tank and the cover on tight, pull the lead going to the lube alert module. Using an ohmmeter, check the reistance of the sensor from the open connection of the sensor back to the ground on the block. With oil in the tank the ohmmeter should read infinite (very high) resistance. When the level in the tank goes low and the engine is running, the lube alert module "sees" the ground (a fault condition). Lube alert modules are wired to see the fault coming in, trigger the alarm on the instrument panel, and then ground out the coil to one of the cylinders (causing the engine speed to drop down.. but still allowing you to limp home).