Electronic Modular Control Panel II+ (EMCP II+) Caterpillar

This diagnostic code is associated with the engine speed sensor. The FMI 3 means that the ECM has determined that an above normal voltage signal from the engine speed sensor has occurred.

Illustration 1	g00530097
System Schematic For The Engine Speed Sensor

The EMCP II + system monitors engine speed. The EMCP II + system uses engine speed in order to accomplish many tasks. These tasks are included in the following list.

• Activating a shutdown for engine overspeed

• Terminating engine cranking

• Determining the oil step speed

• Causing the air shutoff solenoid to engage during some fault shutdowns

The EMCP II + does not control engine speed. The 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 GSC+. The frequency of the signal is directly proportional to the speed of the engine.

The GSC+ treats a CID 190 FMI 3 as a shutdown fault. The engine is not allowed to crank or the engine is not allowed to run when a CID 190 FMI 3 diagnostic code is active.

Note: The Engine Speed Sensor is commonly referred to as magnetic pickup.

Note: Engines that are equipped with an electronic governor or electronic engine control (PEEC) have a separate speed sensor. The cable of the speed sensor that is used by the GSC is marked with one of the following numbers: 21 and 22.

This troubleshooting procedure is for a CID 190 FMI 3 that is active or inactive.

The possible causes of a CID 190 FMI 3 are listed below.

• There is an open in the signal circuit.

Clear the diagnostic code from the fault log after troubleshooting is complete.

Test Step 1. CHECK THE HARNESS AND THE SPEED SENSOR.

1. Turn the engine control switch (ECS) to OFF/RESET.

2. Disconnect the harness connector from the GSC+.

3. At the GSC+ harness connector, measure the resistance from contact "1" to contact "2".

Expected Result:

The resistance should be from 100 to 350 ohms.

Results:

• OK - There is probably an intermittent problem. Proceed to Test Step 2.

• NOT OK - The harness wiring or the speed sensor has failed. Proceed to Test Step 2.

Test Step 2. CHECK FOR AN INTERMITTENT FAULT.

1. Turn the ECS to OFF/RESET.

2. Turn the ECS to STOP.

3. Check the upper display for a CID 190 FMI 3.

Expected Result:

CID 190 FMI 3 should not appear on the upper display.

Results:

• OK - CID 190 FMI 3 does not appear on the upper display. This step has corrected the problem. Stop.

• NOT OK - CID 190 FMI 3 appears on the upper display. Proceed to Test Step 3.

Test Step 3. CHECK THE RESISTANCE OF THE ENGINE SPEED SENSOR.

1. Disconnect the sensor from the engine harness. The sensor remains fastened to the engine.

2. At the connector of the sensor, measure the resistance between contact "1" and contact "2".

Expected Result:

The resistance should be between 100 to 350 ohms.

Results:

• OK - The resistance of the sensor is correct. Proceed to Test Step 4.

• NOT OK - Replace the sensor.

  Repair: Refer to Testing And Adjusting, "Speed Sensor (Engine) - Adjust".

  Stop.

Test Step 4. CHECK THE HARNESS FOR AN OPEN OR A SHORT.

1. Turn the engine control switch (ECS) to OFF/RESET.

2. Disconnect the sensor from the engine harness. The sensor remains fastened to the engine.

3. Disconnect the harness connector from the GSC+.

4. Check for an open circuit. Check the resistance from contact "2" of the sensor harness connector to contact "2" of the GSC+ harness connector. The resistance should be 5 ohms or less.

5. Check for an open circuit. Check the resistance from contact "1" of the sensor harness connector to contact "1" of the GSC+ harness connector. The resistance should be 5 ohms or less.

6. Check for a short circuit. Check the resistance from contact "1" to contact "2" of the GSC+ harness connector. The resistance should be greater than 5000 ohms.

Expected Result:

When the resistance is measured between contact "2" of the sensor harness connector and contact "2" of the GSC+ harness connector, there should be 5 ohms or less.

The resistance from contact "1" of the sensor harness connector to contact "1" of the GSC+ harness connector should be 5 ohms or less.

The resistance from contact "1" to contact "2" of the GSC+ harness connector should be greater than 5000 ohms.

Results:

• OK - The harness functions properly. Proceed to Test Step 5.

• NOT OK - The harness wiring with the incorrect resistance measurement has failed. Repair the failed harness or replace the failed harness. The harness extends from the sensor connector to the connector for the GSC+. Stop.

Test Step 5. CHECK THE SHIELD AND THE CONNECTORS.

1. Turn the engine control switch (ECS) to OFF/RESET.

2. Disconnect the sensor from the engine harness. The sensor remains fastened to the engine.

3. Disconnect the harness connector from the GSC+.

4. The harness has a shield (bare wire) which protects the sensor signal wire from electrical interference. This shield must be securely fastened and the shield must make a good electrical connection to the battery negative post of the GSC+.

5. Within the EMCP II +, check that the shield is securely fastened.

6. Check the connection between the sensor and the mating harness connector. Refer to Testing and Adjusting, "Electrical Connector - Inspect".

Expected Result:

The shield should be securely fastened. The connection between the sensor and the mating harness connector should be secure.

Results:

• OK - The shield is securely fastened. The connection between the sensor and the mating harness connector is secure. Proceed to Test Step 6.

• NOT OK - One of the items is not correct. Repair the harness or replace the harness. Stop.

Test Step 6. INSPECT THE SENSOR AND ADJUST THE SENSOR.

1. Remove the sensor from the engine flywheel housing.

2. Inspect the sensor for damage and remove any debris from the tip.

Expected Result:

No damage should be present.

Results:

• OK - No damage is present. Reinstall the engine speed sensor. Adjust the sensor.

  Repair: For more information, refer to Testing And Adjusting, "Speed Sensor (Engine) - Adjust".

  Proceed to Test Step 7.

• NOT OK - Damage is present. Replace the engine speed sensor.

  Repair: Refer to Testing And Adjusting, "Speed Sensor (Engine) - Adjust".

  Stop.

Test Step 7. CHECK THE STATUS OF THE FAULT.

1. Reconnect the harness connector to the GSC+ and the sensor.

2. Turn the ECS to OFF/RESET and then turn the ECS to STOP.

3. Check the upper display for a CID 190 FMI 3.

Expected Result:

A CID 190 FMI 3 diagnostic code should still be active.

Results:

• OK - A CID 190 FMI 3 is showing on the upper display. The diagnostic code is still active and the engine will not start.

  Repair: It is unlikely that the GSC+ has failed. Exit this procedure and perform this procedure again. If the diagnostic code is still present, replace the GSC+. Refer to Testing and Adjusting, "EMCP Electronic Control (Generator Set) - Replace".

  Stop.

• NOT OK - A CID 190 FMI 3 is not showing on the upper display. These procedures have corrected the problem. The operator may continue with this procedure. Proceed to Test Step 8.

Test Step 8. CHECK THE SIGNAL VOLTAGE.

1. This is an additional check of the circuit. Make sure that all of the harness connectors are connected.

2. Use a multimeter and 7x-1710 Multimeter Probes in order to measure the AC signal voltage. Measure the AC signal voltage between contact "1" and contact "2" on the connector for the GSC+.

3. Start and run the engine at rated speed.

4. Measure the AC signal voltage of the engine speed sensor.

Expected Result:

The voltage should be equal to 2 ACV or greater.

Results:

• OK - The voltage is equal to 2 ACV or greater. The speed sensor circuit is correct. Stop.

• NOT OK - The voltage is not equal to 2 ACV or greater. The most likely cause is improper air gap of the pickup.

  Repair: For more information, refer to Testing And Adjusting, "Speed Sensor (Engine) - Adjust".

  Stop.