Guardian Protection System; Warning System; Warning Horn Location; Warning Light Location - Mercury 15 EFI FourStroke Service Manual

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.

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
Start up
No fault
Overheat
Low oil pressure
Sensor error
Overspeed (20 hp models)
Overspeed (10/15 hp models)
Restrictor (10/15 hp models
only)
*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
90-8M0125265 eng NOVEMBER 2017
Warning Horn
One second
None
Continuous for six seconds
Six beeps
no repeats
None
None
Six beeps
no repeats
Warning Lamp
On
Six flashes
repeats every five minutes
Six flashes
repeats every five minutes
© 2018 Mercury Marine
General Troubleshooting
62873
Description Rev Limit
System test
System normal
Engine overheat
Low oil pressure
2800 RPM
Engine sensor fault
Engine speed too high 6300 RPM*
Engine speed too high 5600 RPM*
Restrictor missing 2800 RPM
Page 1E-5
None
None