MEFI Fuel Injection
Engine Protection Mode System
01-02 Model Years - Engine Mounted Horn System Horn operation: The horn will sound 2 short beeps at each key on as a horn check. This is an audible check so that the operator will know that the horn is working. The horn will sound an “intermittent beep” when there is an “active” DTC stored in the ECM memory. This intermittent beep is one long beep followed by two short beeps. The horn also sounds if S.L.O.W. (Speed Limiting Operational Warning) mode or “engine protection mode” is activated. The horn sounds a steady beeping sound when S.L.O.W. Mode has been activated. System operation: The exhaust temperature switches and the oil pressure switch are all wired in parallel on the oil pressure switch input circuit to the ECM at connector J2-20. The ECM sends out 5 volts looking for a ground through any one of the 3 switches. The riser switches are normally open switches and the oil pressure switch is a normally closed switch. As soon as either one of the 3 switches closes (with the engine running longer than approximately 20 seconds), a “low oil pressure” fault is set in the ECM’s memory and the warning horn sounds. If the problem goes away, there is an approximately 20 second delay before S.L.O.W. mode is cleared and the warning horn is deactivated. Complete system operation and diagnosis is covered in the 7742218 diagnostic book between pages 252 and 255. Both systems use the ECT input for S.L.O.W. mode, and engine response to that input is the same for both systems and is explained on the next page. This system can be equipped with an optional remote mounted horn at the helm.
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