49440 Mercruiser NUT, (.468-32), AUTO TRIM SWITCH

If no oil pressure is indicated, STOP the engine. The engine will be damaged from operating without oil pressure.
Main Module
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Emergency Stop (1) - The emergency stop indicator will flash if the "EMERGENCY STOP" button is used to stop the engine.
System Voltage (2) - The indicator for low system voltage illuminates when the ECM detects a supply of less than 20 VDC.
Engine Overspeed (3) - The engine overspeed indicator illuminates when the Electronic Control Module (ECM) detects an overspeed condition.
Overcrank (4) - A time limit for cranking the engine is programmed into the ECM. A limit for the crank cycle is also programmed. The overcrank indicator illuminates when the engine does not start within the limits.
System Not In Auto (5) - This indicator will light whenever the system is not in automatic mode.
Engine Oil Pressure (6) - This indicator will light if the pressure of the engine oil is outside of the typical range. The engine oil pressure will be highest after a cold engine is started. The engine oil pressure will decrease as the engine warms up. The engine oil pressure will increase when the engine rpm is increased. The engine oil pressure will stabilize when the engine rpm is stable. The typical range for engine oil pressure at low idle rpm is 186 to 344 kPa (27 to 50 psi). The typical range for engine oil pressure at rated rpm is 275 to 600 kPa (40 to 87 psi).
High Coolant Temperature (7) - This indicator will light if the coolant temperature exceeds the boiling temperature of the pressurized cooling system.
Low Coolant Temperature (8) - This indicator will light if the coolant temperature is below the normal operating temperature.
Coolant Level (9) - The low coolant level indicator will light if the coolant level falls below normal.
Low Fuel Level (10) - The low fuel level indicator illuminates when the level of fuel in the fuel tank is low. Gauge Cluster Modules
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Engine Oil Pressure (1) - The engine oil pressure gauge indicates the pressure of the engine oil. The engine oil pressure will be highest after a cold engine is started. The engine oil pressure will decrease as the engine warms up. The engine oil pressure will increase when the engine rpm is increased. The engine oil pressure will stabilize when the engine rpm is stable. The typical range for engine oil pressure at low idle rpm is 186 to 344 kPa (27 to 50 psi). The typical range for engine oil pressure at rated rpm is 275 to 600 kPa (40 to 87 psi).
Coolant Temperature (2) - The coolant temperature gauge indicates the temperature of the engine coolant. The coolant temperature may vary according to the load. The coolant temperature should never be allowed to exceed the boiling temperature of the pressurized cooling system. The operating range for coolant temperature is 88 to 100 °C (190 to 210 °F). Higher temperatures may occur under certain conditions. The sensor for coolant temperature is to be fully submerged in order to detect the temperature correctly. If the engine is operating above the normal temperature range, perform the following procedure:
Reduce the load and reduce the engine rpm.