C-10, C-12, C-15 and C-16 Industrial Engines – Coolant Level Sensor Circuit – Test

System Operation Description:

The coolant level sensor provides a means of monitoring the engine coolant level in order to warn the operator in the event that the coolant level is low. The coolant level sensor is usually located in the top tank of the radiator. The sensor should be immersed in coolant at all times.

Verify that the coolant level has been programmed to “Enabled” on the configuration screen for the Caterpillar Electronic Technician (ET). If the coolant level is not programmed, Cat ET will display “Unavailable” on Cat ET.

Illustration 1	g02044940
Schematic for coolant level sensor

Illustration 2	g02046313
P1 ECM connector (P1-4) 8 V Sensor supply (P1-5) Digital sensor return (P1-46) Coolant level sensor

Illustration 3	g02046255
Terminal locations for the analog sensors at the machine interface connector (16 and 20 cylinder engines) (8) 8 V Supply (9) Digital return (36) Coolant level sensor

Test Step 1. Inspect Electrical Connectors and Wiring

1. Place the engine control in the OFF/RESET mode.

2. Thoroughly inspect the ECM connector, the customer connector, and the connector for the coolant level sensor that is in the circuit. Refer to Troubleshooting, “Electrical Connectors – Inspect” for details.

3. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector, the customer connector, and the sensor connector that is associated with the circuit for the coolant level sensor.

4. Check the ECM Connector (allen head screw) for the proper torque. Refer to Troubleshooting, “Electrical Connectors – Inspect” for details.

5. Check the customer connector (allen head screw) for the proper torque. Refer to Troubleshooting, “Electrical Connectors – Inspect” for details.

Expected Result:

All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion, and of pinch points.

Results:

• OK – The connectors and wiring are OK. Proceed to Test Step 2.

• Not OK – There is a problem with the connectors and/or with the wiring.

  Repair: Repair the wiring and connectors or replace the wiring or the connectors. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem.Verify that the repair eliminates the problem.

  STOP

Test Step 2. Verify that the Coolant Level Sensor is Installed

1. Locate the coolant level sensor on the engine. Verify that a coolant level sensor is installed on the engine.

Expected Result:

The coolant level sensor is installed.

Results:

• OK – The coolant level sensor is installed. Proceed to Test Step 3.

• Not OK – The coolant level sensor is not installed.

  Repair: Change the parameter for the coolant level sensor to “Not Installed”. Verify that the repair eliminates the problem.

  STOP

Test Step 3. Check the Coolant Level

Pressurized System: Hot coolant can cause serious burns. To open the cooling system filler cap, stop the engine and wait until the cooling system components are cool. Loosen the cooling system pressure cap slowly in order to relieve the pressure.



1. Stop the engine.

2. After allowing the engine to cool, check the coolant level. Refer to the Operation and Maintenance Manual for the proper procedure to check the coolant level.

Expected Result:

The coolant is at the proper level.

Results:

• OK – The coolant is at the proper level. Proceed to Test Step 4.

• Not OK – The coolant level is low.

  Repair: Add coolant according to the procedure in the Operation and Maintenance Manual.Verify that the repair eliminates the problem. Identify the source of the coolant leak and fix the problem.

  STOP

Test Step 4. Monitor the Status of “Coolant Level” on Cat ET

1. Connect Cat ET to the service tool connector.

2. Place the engine control in the ON mode and monitor the status of “Coolant Level” on Cat ET.

3. Place the engine control in the OFF/RESET mode.

Expected Result:

The status is “OK”.

Results:

• OK – The status is “OK”. Proceed to Test Step 5.

• Not OK – The status is “Low”. Proceed to Test Step 6.

Test Step 5. Disconnect the Coolant Level Sensor and Monitor the Status of “Coolant Level” on Cat ET

1. Disconnect the J800/P800 coolant level sensor connector.

2. Place the engine control in the ON mode and monitor the status of “Coolant Level” on Cat ET.

3. Place the engine control in the OFF/RESET mode.

Expected Result:

The status indicates “Low” when the sensor is disconnected.

Results:

• OK – The status is “Low” when the sensor is disconnected.

  Repair: If a diagnostic code is active for the coolant level sensor, replace the coolant level sensor.Verify that the repair eliminates the problem.

  STOP

• Not OK – The status is “OK” when the sensor is disconnected. Proceed to Test Step 7.

Test Step 6. Jumper the Harness and Monitor the Status of “Coolant Level” on Cat ET

1. Disconnect the J800/P800 coolant level sensor connector.

2. Install a jumper wire between P800-B (Analog Sensor Return) and P800-C (Signal).

   Refer to Illustration 1 for terminal locations.

3. Place the engine control in the ON mode and monitor the status of “Coolant Level” on Cat ET.

4. Place the engine control in the OFF/RESET mode.

5. Remove the jumper wire.

Expected Result:

The status indicates “OK” when the jumper wire is installed.

Results:

• OK – The ECM and the wiring to the coolant level sensor are OK.

  Repair: Replace the coolant level sensor.Verify that the repair eliminates the problem.

  STOP

• Not OK – Shorting the circuit does not affect the status on Cat ET. Proceed to Test Step 7.

Test Step 7. Check for Opens in the Wiring

1. Ensure that the engine control is in the OFF/RESET mode.

2. Disconnect the J1/P1 (ECM connector) and disconnect the J61/P61 (Customer connector). The J800/P800 (coolant level sensor connector) should already be disconnected.

3. Measure the resistance between the following terminals:

   Refer to Illustrations 2 and 3 for terminal locations.

   • P1-4 to J61-8

   • P1-5 to J61-9

   • P1-46 to J61-36

   • P61-8 to P800-A

   • P61-9 to P800-B

   • P61-36 to P800-C

Expected Result:

The resistance is less than 5 Ohms for each measurement.

Results:

• OK – The resistance is less than five Ohms for each measurement. Proceed to Test Step 8.

• Not OK – The resistance is more than five Ohms for a measurement. There is an open circuit or excessive resistance in the harness or the connectors.

  Repair: Repair the circuit.Verify that the repair eliminates the problem.

  STOP

Test Step 8. Check for Shorts in the Wiring

1. Reconnect the customer connector J61/P61.

2. The following connectors should already be disconnected and the engine control should be in the OFF mode.
   • J1/P1 (ECM connector)

   • J800/P800 (coolant level sensor connector)

3. Measure the resistance between the following terminals and every pin on ECM connector P1. Measure the resistance between the following terminals and every pin on ECM connector P1.

   Refer to Illustrations 2 and 3 for terminal locations.

   • P1-4

   • P1-5

   • P1-46

Expected Result:

The resistance is greater than 20,000 Ohms for each measurement.

Results:

• OK – The resistance is greater than 20,000 Ohms for each measurement. There are no short circuits in the harness. Proceed to Test Step 9.

• Not OK – The resistance is less than 20,000 Ohms for a measurement. There is a short circuit in the harness.

  Repair: Repair the circuit.Verify that the repair eliminates the problem.

  STOP

Test Step 9. Short the Signal at the ECM

1. The J800/P800 coolant level sensor connector should already be disconnected.

2. Disconnect ECM connector P1. Remove wire E452-WH from ECM connector P1-46. Install a wire jumper into the socket P1-46.

3. Install a jumper wire between the wire jumper in P1-46 (coolant level sensor signal) and engine ground.

   Refer to Illustration 2 for terminal locations.

4. Reconnect ECM connector P1.

5. Place the engine control in the ON mode and monitor the status of “Coolant Level” on Cat ET.

6. Monitor the status of “Coolant Level” on Cat ET while the jumper wire is installed.

7. Monitor the status of “Coolant Level” on Cat ET while the jumper wire is not installed.

Expected Result:

The status of the switch is “Low” when the jumper wire is not grounded. The status of the switch is “OK” when the jumper wire is connected to ground.

Results:

• OK – The ECM is properly reading the switch input.

  Repair: Refer to Troubleshooting, “Electrical Connectors – Inspect” if the problem is intermittent.

  STOP

• Not OK – The ECM is not reading the switch input.

  Repair: Verify your results.Temporarily replace the ECM. If the new ECM fixes the problem, permanently install the new ECM.

  STOP