1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 124Get this manual
Models Not Equipped With Test Button (3 and Cylinder) DESCRIPTION
Self-test of the warning system is performed by turning the ignition key to the "RUN" positionA steady beep is indicative of an overheat conditionAn intermittent beep refers to low oil conditionBoth overheat and low oil conditions are monitored by warning module mounted on the starboard side of the engine blockaWarning Module