Electronic Modular Control Panel II (EMCP II) for EUI Engines Caterpillar

Illustration 1	g00485064
System Schematic For Speed Sensor (Engine)

Note: This speed sensor is sometimes referred to as a magnetic pickup (MPU).

The EMCP II monitors engine speed in order to use the information when the information is needed for other tasks. Other tasks include activating an engine overspeed shutdown, terminating engine cranking, determining the oil step speed and causing the air shut off solenoids 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 from passing ring gear teeth at the rate of one pulse per tooth. The sensor sends the GSC a sine wave signal in which the frequency is in direct proportion to the speed of the engine.

The GSC treats a CID 190 as a shutdown fault. The engine is not allowed to crank when this diagnostic code is active.

Note: Engines that are equipped with an electronic governor have an additional speed sensor.

Note: Faults are created when the harness connector (40 contact) is disconnected from the GSC during these troubleshooting procedures. Clear these created faults after the particular fault is corrected. In a properly operating system, when the harness connector is removed from the GSC, the following diagnostic codes are recorded:

• CID 100 FMI 2 pressure sensor (engine oil)

• CID 110 FMI 2 temperature sensor (engine coolant)

• CID 111 FMI 3 fluid level sensor (engine coolant)

• CID 190 FMI 3 speed sensor (engine)

• CID 336 FMI 2 switch (engine control)

• CID 590 FMI 9 engine ECM

Procedure

The following conditions could be the cause of a CID 190 FMI 2:

• The frequency of the signal is beyond accepted limits (short to "B-").

• The air gap of the speed sensor is too large.

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

1. Check the harness and the sensor.

   1. Turn the 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 100 to 350 ohm.

      Results:

      • OK - The fault is most likely intermittent. Reconnect the harness connector to the GSC. Turn the ECS to OFF/RESET and then turn the ECS to STOP. Verify that a CID 190 remains active on the upper display.

      • If a CID 190 is showing, continue with this procedure. Proceed to next step.

      • If a CID 190 is NOT showing, this step has corrected the fault. STOP. If you are desired then continue with this procedure. Proceed to next step.

      • NOT OK - The harness wiring or the speed sensor is faulty. Proceed to 2.

2. Check the resistance of the sensor.

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

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

      Expected Result: The resistance should be 100 to 350 ohm.

      Results:

      • OK - The resistance of the speed sensor is correct. Proceed to next step.

      • NOT OK - Replace the speed sensor. Also, see Testing And Adjusting, "Speed Sensor (Engine) - Adjust". STOP.

3. Check the harness for an open and a short.

   The ECS remains in the OFF/RESET position. The speed sensor and the GSC remain disconnected from the harness.

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

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

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

      Expected Result: The resistance for 3.a and 3.b should be 5 ohms or less. The resistance for step 3.c should be greater than 5000 ohms.

      Results:

      • OK - The harness functions properly. Proceed to next step.

      • NOT OK - The harness wiring with the incorrect resistance measurement is faulty. Replace the faulty harness from the speed sensor to the GSC connector. STOP.

4. Check the shield and the connectors.

   The ECS remains in the OFF/RESET position. The speed sensor and the GSC remain disconnected from the harness. The harness has a shield (bare wire) which protects the signal wire for the speed sensor from electrical interference. It is important that this shield is securely fastened and makes good electrical connection to the inside enclosure of EMCP II.

   1. Within the EMCP II, check that the shield is securely fastened to a GSC mounting stud.

   2. Within the EMCP II, measure the resistance from the shield to a metal surface within the enclosure of EMCP II. A good reference point is a mounting screw for a component that directly contacts the metal enclosure. The resistance should be 5 ohms or less.

   3. Check the connector of the speed sensor and the mating harness connector. Proceed to Testing And Adjusting, "Electrical Connector - Inspect".

      Expected Result: The shield should be securely fastened. The resistance in 4.b should be 5 ohms or less. Also, the connectors should be proper.

      Results:

      • OK - Proceed to next step.

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

5. Inspect the sensor and adjust the sensor.

   1. Remove the speed sensor from the engine flywheel housing.

   2. Inspect the speed sensor for damage. Remove any debris from the tip.

      Expected Result: No damage should be present.

      Results:

      • OK - Reinstall and adjust the speed sensor. See Testing And Adjusting, "Speed Sensor (Engine) - Adjust". Proceed to next step.

      • Not OK - Replace the speed sensor. Also, see Testing And Adjusting, "Speed Sensor (Engine) - Adjust". STOP.

6. Check the status of the fault.

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

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

   3. Verify that CID 190 is showing on the upper display.

      Expected Result: A CID 190 FMI 2 is active.

      Results:

      • No - These procedures have corrected the fault. STOP. If you are desired then continue with this procedure. Proceed to next step.

      • Yes - A CID 190 is showing, the diagnostic code is still active and the engine will not start. Use the process of elimination to find the faulty component. Stop when the diagnostic code is no longer showing. First, replace the speed sensor and adjust the speed sensor. Then replace the harness. Finally, replace the GSC.

7. Check the signal voltage.

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

   1. Set up a multimeter with 7X-1710 Multimeter Probe Group in order to measure the ACV from contact "1" to contact "2" of the GSC connector.

   2. Start and run the engine at rated speed.

   3. Measure the ACV of the speed sensor.

      Expected Result: The voltage should be greater than 10 ACV.

      Results:

      • OK - The speed sensor circuit checks correctly. STOP.

      • NOT OK - The most likely cause is improper air gap of the speed sensor. Repeat step 5. STOP.