Engine Guardian Strategy; Warning Horn Signals - Mercury Mercruiser Tow Sport 5.7 MPI Manual

Engine Guardian Strategy

IMPORTANT: Boat speed could be reduced to idle and may not respond to the throttle.
Engine Guardian strategy is designed to help reduce the potential for engine damage by reducing engine power when a
potential problem is sensed by the ECM. Engine Guardian monitors:
• Oil pressure
• Coolant temperature
• Seawater pressure
• Engine overspeed
• Exhaust manifold temperature (8.1 and 496 models only)
Also the Engine Guardian strategy will reduce engine power to 90 percent of maximum if any sensor on the power package
fails.
For example, if the water inlet becomes partially blocked, Engine Guardian strategy will reduce the available power level of the
engine to help prevent damage from decreased water flow to the engine. If the debris passes through and full water flow is
restored, engine power levels are restored to normal.
To avoid a possible recurrence of the problem you should contact an authorized dealer. The ECM stores the fault and with this
information the technician will be able to more rapidly diagnose problems.

Warning Horn Signals

Most faults will cause the warning horn circuit to activate. How the warning horn activates depends on how serious the problem
is. There are four warning horn states:
• Caution – horn signal varies with product line and calibration. Minimal guardian.
• Warning – horn signal varies with product line and calibration.
• Severe – horn is beeping constantly.
• Critical – horn is beeping constantly and guardian will be at forced idle.
In addition, depending on the gauge package, there will be warning icons and fault messages on the dash mounted gauges.
90-8M0076545 NOVEMBER 2012
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Section 2 - Getting to Know Your Power Package
Page 23