Mercury 15 EFI FourStroke, Service Manual

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Guardian Protection System
The Guardian Protection System monitors critical engine functions and will reduce engine power accordingly in an attempt to
keep the engine running within safe operating parameters.
IMPORTANT: The Guardian Protection System cannot guarantee that powerhead damage will not occur when adverse
operating conditions are encountered. The Guardian Protection System is designed to 1) warn the boat operator that the
engine is operating under adverse conditions and 2) reduce power by limiting maximum RPM in an attempt to avoid or reduce
the possibility of engine damage. The boat operator is ultimately responsible for proper engine operation.
Warning System
Warning Horn Location
A warning horn is located near the front of the engine, under the cowl. On remote control models, an additional warning horn is
located inside the remote control or connected to the ignition key switch.
Warning Light Location
The warning light is located on the front of the engine, just below the top cowl. It will turn on or flash to alert the operator to the
warning system situations listed in
Warning System Operation
.
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Warning System Operation
Overview
The warning system is designed to alert the operator of problems with the engine's operation. The following chart provides a
brief overview of the system operation in certain situations.
Function Warning Horn Warning Lamp Description Rev Limit
Start up One second System test None
No fault None System normal None
Overheat
Continuous for six seconds On
Engine overheat
2800 RPM
Low oil pressure Low oil pressure
Sensor error
Six beeps
no repeats
Six flashes
repeats every five minutes
Engine sensor fault
Overspeed (20 hp models) None Engine speed too high 6300 RPM*
Overspeed (10/15 hp models) None Engine speed too high 5600 RPM*
Restrictor (10/15 hp models
only)
Six beeps
no repeats
Six flashes
repeats every five minutes
Restrictor missing 2800 RPM
*Engine misfire may be noticed.
Warning System States
The warning system, comprised of horn and light, serves to alert the operator to most engine system faults. There are two
warning states:
•
Caution
• Critical
General Troubleshooting
90-8M0125265 eng NOVEMBER 2017 © 2018 Mercury Marine Page 1E-5