Warning Display Screens - Mercury 225 EFI Service Manual

Warning Display Screens

The engine has an "Engine Guardian System". The ECM Engine control module monitors
the critical sensors on the engine for any early indications of problems. The Guardian System
will respond to a problem by reducing engine speed in order to maintain a safe operating condi-
tion. The System Monitor will display the alarm.
The warning system will alert the operator to the potential problems. Refer to the pages
following for explanation of the problem and the correct action to take .
ALARM – OVERHEAT
The Bell and Temperature icons are displayed and the warning horn begins sounding con-
tinuously to inform the driver that there is insufficient water pressure in the cooling system.
The Engine Guardian System will start limiting engine power.
If the engine overheats, immediately reduce throttle speed to idle. Shift into neutral. If out-
board: check for a steady stream of water coming out of the water pump indicator hole.
NOTE: The throttle will have to be returned to idle to reset the system.
If no water is coming out of the water pump indicator hole or flow is intermittent, stop engine
and check cooling water intake holes for obstruction. If no obstruction is found, this may indicate
a blockage in the cooling system or a water pump problem. Operating the engine while over-
heated will cause engine damage.
If a steady stream of water is coming out of the water pump indicator hole and the warning
horn continues to sound, there still may be insufficient cooling water or an engine problem.
Stop engine. Operating the engine while overheated will cause engine damage.
The overheat problem must be corrected before you can resume normal operation.
NOTE: If you are in a stranded situation, stopping the engine and allowing it to cool back
down will usually allow some additional low speed (idle) running time before the engine starts
to overheat again.
ALARM – LOW WATER PRESSURE
The Bell and Water Pressure icons are displayed and the warning horn begins sounding contin-
uously to inform the driver that there is insufficient water pressure in the cooling system. The
Engine Guardian System will start limiting engine power.
Some causes of insufficient cooling water pressure are (1) obstructed cooling water intake
holes (2) blockage in the cooling system or a water pump problem. Running the engine with
the cooling water intake holes out of the water.
NOTE: The throttle will have to be returned to idle to reset the system.
If the warning system is activated, immediately reduce throttle speed to idle. Shift engine into
neutral and check for a steady stream of water coming out of the water pump indicator hole.
90-884294 OCTOBER 2001
WIRING DIAGRAMS
Page 2D-27