Caution; Severe; Testing The Audio Warning System; Guardian Strategy - Mercury 350 MAG Manual

Caution

If a caution state is detected, the audio warning system will sound for six one‑second intervals.
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Below are some examples of a caution state:
• Drive oil is low (sterndrive models only)
• Sensor failure

Severe

IMPORTANT: Operators are advised to contact an authorized Mercury MerCruiser dealer if a severe fault is activated.
If a severe state is detected, the audio warning system sounds for six seconds, turns off for six seconds, and sounds for six more
seconds. Then the audio warning system sounds for two half‑second intervals every sixty seconds.
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a - Horn (on or off)
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Below are some examples of a severe state:
• Transmission fluid temperature is too hot (inboard models only)
• Engine oil pressure is too low
• Engine temperature is too hot
• Seawater pressure is too low
• Transmission pressure is low (inboard models only)

Testing the Audio Warning System

1. Turn the ignition switch to the on position without cranking the engine.
2. Listen for the audio alarm. The alarm will sound if the system is functioning correctly.

Guardian Strategy

Engine Guardian reduces the potential for engine damage by restricting engine power when the PCM detects a potential problem.
Below are some examples of what Engine Guardian monitors:
• Oil pressure
• Engine overspeed
• Exhaust manifold temperature
IMPORTANT: Guardian can reduce power anywhere from 100% to idle, depending on the severity of the problem. If forced to
idle, boat speed might not respond to throttle operation.
The PCM stores the fault for diagnostics. For example, if the water inlet becomes partially blocked, Guardian reduces 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, Guardian restores engine power to normal. To avoid recurrence of the problem, contact an authorized
Mercury MerCruiser dealer.
As another example, Transmission Guardian is a MerCruiser DTS feature that protects transmissions from clutch damage.
Transmission Guardian monitors the clutch pack pressure in forward and reverse gears. If the transmission fluid pressure drops
below a predetermined level, Transmission Guardian lowers the engine torque and speed to prevent clutch slippage. To avoid
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.
90-8M0050539 MAY 2011
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Section 2 - Getting to Know Your Power Package
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