Mercury 225 EFI Service Manual page 210

WIRING DIAGRAMS
BATTERY (a)
The warning message is designed to come on and the Engine Guardian System will start
limiting engine power when the electrical system is not charging or the battery charge is
low. If the message appears immediately after starting, it is possible that the engine alter-
nator can recharge the battery after operating awhile. If this message appears while driv-
ing or comes on after starting and continued to be displayed, the electrical system must
be checked to determine the cause of the problem to avoid being stranded with a dead
battery. To help the alternator recharge the battery quickly, you can reduce the load on
the electrical system by turning off any unneeded accessories.
NOTE: The throttle will have to be returned to idle to reset the system.
ENGINE DATA BUS (b)
This message tells you the data communication link between the tachometer and engine
is not connected. Check for disconnected wires. Be sure the gray and brown/white wires
are connected to the diagnostic port plug on the engine. See SmartCraft Gauge Wiring.
UNIT MISMATCH (c)
(Multi Engines) This message tells you that the tachometers are not calibrated alike. (For
example, this could happen if one tachometer readings are in English and the another is
in Metric. Re-calibrate the tachometers.
NOTE: When calibrating multi tachometers, have all the tachometers powered up at the
same time while calibrating.
LOW FUEL LEVEL (d)
This message tells you that the fuel level in the fuel tank is critically low. Stop for fuel im-
mediately to avoid running out. The engine must be shut off to reset the warning system.
LOW OIL LEVEL (e)
This message tells you that the oil level in the remote oil tank is low. Stop and refill the
oil tank immediately to avoid running out. The engine must be shut off to reset the warning
system.
FAULT-SENSOR (f)
This message informs you if one of the sensors is not functioning correctly.
If the throttle sensor has failed, the warning horn will sound a continuous beeping and the
engine will not reach its full power.
If the throttle sensor and manifold pressure sensor both fail, the warning horn will sound
a continuous beeping and the engine speed will stay at idle.
If the temperature or block pressure sensor should fail, the Engine Guardian System will
limit the maximum engine power by 25 percent.
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90-884294 OCTOBER 2001