Obdm; Testing The Audio Warning System; Guardian Strategy - MerCruiser 496 MAG Owner's Manual

If a severe fault is detected, the audio warning system will sound for six seconds, turn off for six seconds, then sound for six more
seconds.
a
a - Horn (on or off)
b - Time (in seconds)
Below are some examples of a severe fault:
• Transmission fluid temperature is too hot
• Engine oil pressure is too low
• Engine temperature is too hot
• Seawater pressure is too low
• Transmission pressure is low

OBDM

If an OBDM fault is detected, the audio warning system sound with one five‑second horn, then one short, 1/2‑second horn every
60 seconds for certain faults related to the emissions or fuel system. See your authorized Mercury MerCruiser dealer for assistance.
a
a - Horn (on or off)
b - Time (in seconds)

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.
90-899883274 MARCH 2008
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Section 2 - Getting to Know Your Power Package
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