BOLT 6I0846 - Caterpillar

System Operation Description:The EMCP 4 performs the following using an independent engine speed sensor that is dedicated to EMCP 4 use only
Determines the engine speed, in rpm, from the magnetic pickup (engine speed sensor) input pins
Detects diagnostics on the sensor
Annunciates an engine over/under speed conditionThe engine speed sensor is mounted on the flywheel housing of the engine.The sensor creates a sine wave signal. The signal is created from passing ring gear teeth. The rate of the signal is one pulse per tooth. The sensor sends the sine wave signal to the EMCP 4. The frequency of the signal is directly proportional to the speed of the engine.Conditions Which Generate This Code:This code is generated when the EMCP 4 has determined that an incorrect signal from the engine speed sensor has occurred or an overspeed/underspeed condition has occurred.Refer to the engine Troubleshooting manual to for more information on engine over/under speed conditions for your particular genset.
Illustration 1 g01103901Note: The engine speed sensor is commonly referred to as magnetic pickup.Test Step 1. PERFORM THE INITIAL CHECK.
Check for active diagnostic codes on the engine ECM and the EMCP 4. If any codes are present, correct the diagnostic codes first. Expected Result:No other diagnostic codes or indicators are active.Results:
OK - No other diagnostic codes or indicators are active. Proceed to Test Step 2
NOT OK - Another diagnostic code is active or an indicator is active.Repair: Exit this procedure. Troubleshoot the active code or indicator. Resume normal operation and verify that the problem has been corrected.STOPTest Step 2. CHECK THE SETPOINTS.
View the "Engine Speed Monitor" setpoints. Make a note of all the setpoints. See Testing and Adjusting, "Electronic Control Module (Generator Set) - Configure". Compare the setpoints against the default setpoints of the particular generator set. Expected Result:The setpoints are correct.Results:
OK - The setpoints are correct for your particular genset. Proceed to Test Step 3
NOT OK - The setpoints are NOT correct.Repair: Reprogram the setpoints. Reset the genset. Resume normal operation and verify that the problem has been corrected.STOPTest Step 3. CHECK THE HARNESS AND THE SPEED SENSOR.
Press the stop key on the EMCP 4 control.
Disconnect the harness connector from the EMCP 4.
At the EMCP 4 harness connector, measure the resistance from contact 66 to contact 67. Expected Result:The resistance should be from 100 to 350 ohms.Results:
OK - There is probably an intermittent problem. Proceed to Test Step 4.
NOT OK - The harness wiring or the speed sensor has failed.Repair: Replace the harness.STOPTest Step 4. CHECK FOR AN INTERMITTENT FAULT.
Press the stop key on the EMCP 4 control.
Check the EMCP 4 display for a speed sensor diagnostic code. Expected Result:A speed sensor diagnostic code should not appear on the display.Results:
OK - A speed sensor diagnostic code does not appear on the EMCP 4 display. This step has corrected the problem.STOP
NOT OK - A speed sensor diagnostic code appears on the EMCP 4 display. Proceed to Test Step 5.Test Step 5. CHECK THE RESISTANCE OF THE ENGINE SPEED SENSOR.
Disconnect the sensor from the engine