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| Illustration 1 | g01436869 |
Simplified System Schematic For Engine Coolant Loss Sensor (ECLS) | |
The EMCPII+P system monitors engine coolant in order to protect the engine in case of a coolant temperature problem. The engine coolant loss function is an option that 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+P. When coolant is NOT present at the sensor, a high signal is sent to the GSC+P. A high signal is approximately +5 DCV. When coolant is present at the sensor, a low signal (approximately 0 DCV) is sent to the GSC+P.
Note: The GSC+P is usually programmed to treat coolant loss sensor problems as an alarm fault. P004 is equal to 0. If the GSC+P 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.
The possible causes of a CID 111 FMI 3 are listed below.
- A short from "BATT+" to 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 diagnostic code is active. The GSC+P treats a CID 111 FMI 3 as an alarm fault. Active alarm faults are shown on the display when the alarm code 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. Refer toTesting 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 CID 269 FMI 3 or a CID 269 FMI 4 is active, correct the diagnostic code prior to proceeding with this procedure.
Test Step 1. CHECK THE SENSOR VOLTAGE SUPPLY CIRCUIT.
- Turn the ECS to OFF/RESET. Then, turn the ECS to the STOP position.
- Disconnect the sensor from the engine harness. The sensor remains fastened to the engine.
- At the engine harness side of the sensor connector, measure the voltage (DCV) that is between pin "A" and pin "B". Pin "A" is the supply for the sensor. Pin "B" is the sensor ground.
Expected Result:
The voltage should be 8.0 DCV (± 0.5 DCV).
Results:
- OK - The voltage is 8.0 DCV (± 0.5 DCV). Proceed to Test Step 2.
- NOT OK - The sensor voltage supply circuit has failed. Proceed to Test Step 5.
Test Step 2. CHECK THE SIGNAL CIRCUIT.
- Turn the ECS to OFF/RESET. Then, turn the ECS to the STOP position.
- Disconnect the sensor from the engine harness. The sensor remains fastened to the engine.
- At the engine harness side of the sensor connector, measure the voltage (DCV) between pin "C" and pin "B". Pin "C" is the signal. Pin "B" is the sensor ground.
Expected Result:
The voltage should be 2.5 DCV (± 0.5 DCV).
Results:
- OK - The voltage is 2.5 DCV (± 0.5 DCV). The signal circuit functions properly. Proceed to Test Step 3.
- NOT OK - The voltage is equal to the positive battery terminal ("BATT+"). The engine harness has failed.
Repair: The signal circuit that is within the engine harness is shorted to the "BATT+". Troubleshoot and repair the engine harness.
STOP
- The voltage is NOT 2.5 DCV (± 0.5 DCV) and the voltage is NOT equal to BATT+. - The GSC+P or the harness has failed. Proceed to Test Step 4.
Test Step 3. CHECK THE SENSOR.
- Turn the ECS to OFF/RESET.
- Turn the ECS to the STOP position.
- Disconnect the sensor from the engine harness. The sensor remains fastened to the engine.
- Turn the ECS to OFF/RESET.
- Turn the ECS to STOP.
Expected Result:
CID 111 FMI 3 should no longer appear on the upper display.
Results:
- OK - CID 111 FMI 3 no longer appears on the upper display.STOP
- NOT OK - CID 111 FMI 3 is still showing on the upper display. The sensor has failed. Replace the sensor.STOP
Test Step 4. CHECK FOR A SHORTED HARNESS.
- Turn the ECS to OFF/RESET.
- Disconnect the sensor from the engine harness. The sensor remains fastened to the engine.
- Disconnect the harness connector from the GSC+P.
- At the GSC+P harness connector, measure the resistance from signal pin "13" to all other pins of the connector.
Expected Result:
For each measurement, the resistance should be greater than 5000 ohms.
Results:
- OK - For each measurement, the resistance is greater than 5000 ohms. The harness functions properly. Proceed to Test Step 5.
- NOT OK - At one or more of the measurements, the resistance is less than 5000 ohms.
Repair: The harness wiring with the incorrect resistance is shorted in the harness. Troubleshoot and repair the failed harness wiring. The fault is between the sensor connector and the GSC+P harness connector.
STOP
Test Step 5. CHECK FOR AN OPEN HARNESS.
- Turn the ECS to OFF/RESET.
- Disconnect the sensor from the engine harness. The sensor remains fastened to the engine.
- Disconnect the harness connector from the GSC+P.
- Measure the resistance of the ground circuit. The ground circuit is from pin "B" of the sensor harness connector to pin "31" of the GSC+P harness connector.
- Measure the resistance of the signal circuit. The signal circuit is from pin "C" of the sensor harness connector to pin "13" of the GSC+P harness connector.
- Measure the resistance of the sensor voltage supply circuit. The sensor voltage supply circuit is from pin "A" of the sensor harness connector to pin "9" of the GSC+P harness connector.
Expected Result:
For each measurement, the resistance should be 5 ohms or less.
Results:
- OK - For each measurement, the resistance is 5 ohms or less. The harness functions properly. Proceed to Step 6.
- NOT OK - The harness wiring with the incorrect resistance measurement is open.
Repair: The harness wiring has failed. Troubleshoot and repair the failed harness wiring between the sensor connector and the GSC+P harness connector.
STOP
Test Step 6. CHECK THE ELECTRICAL CONNECTORS.
- Check the electrical connectors, terminals and wiring. Refer 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. STOP
- NOT OK - Repair the area with the problem.
Repair: Start the engine. If the CID 111 FMI 3 is still showing, the GSC+P may have failed. It is unlikely that the GSC+P has failed. Exit this procedure and perform this entire procedure again. If the problem remains, replace the GSC+P. Refer to Testing And Adjusting, "EMCP Electronic Control (Generator Set) - Replace".
STOP