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

Illustration 1	g00527487
System Schematic For Engine Coolant Loss Sensor(ECLS)

The EMCP II+ monitors engine coolant for loss of coolant in order to protect the engine in case of a coolant temperature problem. The engine coolant loss function is optional. The engine coolant loss function requires the presence of the optional coolant loss sensor. The coolant loss sensor is usually mounted near the top of the radiator.

The sensor is powered by an 8 volt sensor supply from the GSC+. When coolant is NOT present at the sensor, a high signal (approximately +5 DCV) is sent to the GSC+. When coolant is present at the sensor, a low signal (battery negative) is sent to the GSC+.

Note: The GSC+ is usually programmed to treat a coolant loss sensor fault as an alarm fault. P004 is equal to 0. If the GSC+ is programmed to shutdown, P004 is equal to 1. The operator is not required to press the "Alarm Codes" key in order to view the CID 111 FMI 3. The CID 111 FMI 3 is automatically shown on the upper display.

Note: Faults are created when the harness connector is disconnected from the GSC+ during these troubleshooting procedures. Clear the created faults after the particular fault is corrected and after the particular fault is cleared. In a system that is operating properly, when the harness connector is removed from the GSC+, the following diagnostic fault 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 175 FMI 3 - Temperature Sensor (Engine Oil)

CID 190 FMI 3 - Speed Sensor (Engine)

CID 336 FMI 2 - Switch (Engine Control)

CID 590 FMI 9 - Engine (ECM)

The possible causes of a CID 111 FMI 3 fault are listed below.

• A short circuit to battery positive of the sensor signal.

• An open circuit of the sensor signal.

Begin performing these procedures only when CID 111 FMI 3 is showing and the "DIAG" indicator is FLASHING on the upper display. The flashing indicator means that the fault is active. The GSC+ treats a CID 111 FMI 3 fault as an alarm fault. Active alarm faults are shown on the display when the alarm codes key is pressed and the engine control switch (ECS) is in any position except the OFF/RESET position. For an inactive fault, the problem may be intermittent. See Testing And Adjusting, "Electrical Connector - Inspect" in order to troubleshoot an inactive fault. Also use the preceding system schematic. Clear the fault from the fault log after troubleshooting is complete.

Note: If a sensor supply fault (CID 269) is active, correct the sensor supply fault prior to proceeding with this procedure.

1. Check the Sensor Voltage Supply Circuit.

   1. Turn the ECS to OFF/RESET. Then, turn the ECS to the STOP position.

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

   3. At the engine harness side of the sensor connector, measure the voltage (DCV) that is between contact "A" and contact "B". Contact "A" is the supply for the sensor. Contact "B" is the sensor ground.

      Expected Result: The voltage should be 8.0 ± 0.5 DCV.

      Results:

      • OK: The sensor voltage supply circuit functions properly. Proceed to Step 2.

      • NOT OK: The sensor voltage supply circuit is faulty. Check the upper display for a sensor supply fault (CID 269). Correct this fault. If a sensor supply fault (CID 269) is not showing on the upper display, then the engine harness has an open circuit. Proceed to Step 4.

2. Check the Signal Circuit. The ECS remains in the STOP position and the sensor remains disconnected from the engine harness.

   1. At the engine harness side of the sensor connector, measure the voltage (DCV) between contact "C" and contact "B". Contact "C" is the signal. Contact "B" is the sensor ground.

      Expected Result: The voltage should be 2.5 ± 0.5 DCV.

      Results:

      • OK: The signal circuit functions properly. Verify this result by checking if the fault remains present. Reconnect the sensor. Turn the ECS to OFF/RESET. Then, turn the ECS to STOP. If the CID 111 FMI 3 fault is still showing on the upper display, the sensor is faulty. Replace the sensor. STOP.

      • NOT OK: The voltage is equal to the battery positive. The engine harness is faulty. The signal circuit within the engine harness is shorted to the battery positive. Troubleshoot and repair the engine harness. STOP.

      • NOT OK: Voltage is NOT 2.5 ± 0.5 DCV. Voltage is NOT equal to the battery positive. The GSC+ or the harness is faulty. Proceed to Step 3.

3. Check for a Shorted Harness. When you are performing this Step, see the preceding System Schematic. The sensor remains disconnected from the engine harness.

   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 signal contact "13" to all other contacts of the connector.

      Expected Result: For each measurement, the resistance should be greater than 5000 ohms.

      Results:

      • OK: The harness functions properly. Proceed to Step 4.

      • NOT OK: The harness wiring with the incorrect resistance is shorted in the harness. Troubleshoot and repair the faulty harness wiring between the sensor connector and the GSC+ connector. STOP.

4. Check for an Open Harness. When you are performing this Step, see the preceding System Schematic. The ECS remains in the OFF/RESET position. The sensor remains disconnected from the engine harness and the GSC+ remains disconnected from the harness connector.

   1. Measure the resistance of the ground circuit. The ground circuit is from contact "B" of the sensor harness connector to contact "31" of the GSC+ harness connector.

   2. Measure the resistance of the signal circuit. The signal circuit is from contact "C" of the sensor harness connector to contact "13" of the GSC+ harness connector.

   3. Measure the resistance of the sensor voltage supply circuit. The sensor voltage supply circuit is from contact "A" of the sensor harness connector to contact "9" of the GSC+ harness connector.

      Expected Result: For each measurement, the resistance should be 5 ohms or less.

      Results:

      • OK: The harness functions properly. Proceed to Step 5.

      • NOT OK: The harness wiring with the incorrect resistance measurement is open. The harness wiring is faulty. Troubleshoot and repair the faulty harness wiring between the sensor connector and the GSC+ connector. STOP.

5. Check the Electrical Connectors.

   1. Check the electrical connectors, terminals and wiring. Proceed to Testing And Adjusting, "Electrical Connector - Inspect".

      Expected Result: All connectors, terminals and wiring should function properly.

      Results:

      • OK: Connect all harness connectors that were previously disconnected. Start the engine. If the CID 111 FMI 3 fault is still showing, replace the GSC+. See Testing And Adjusting, "EMCP Electronic Control (Generator Set) - Replace"for more information. STOP.

      • NOT OK: Repair the faulty area. STOP.