EDGE AS 4326786 - Caterpillar

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.
Drain the coolant below the level of the coolant level sensor.
Restore electrical power to the ECM.
Monitor the status of the appropriate "Coolant Level" on Cat ET.Note: Wait at least 30 seconds for activation of the status indicator.
Remove electrical power from the ECM.If the status of the "Coolant Level" is "OK", replace the sensor.If the status for the coolant level is "LOW", the circuit for the coolant level sensor is OK. There may be an intermittent problem in the harness or in a connector. Fill the cooling system according to the procedure in the Operation and Maintenance Manual. Return the engine to service. If an intermittent electrical problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect" for troubleshooting information.STOP
Not OK - Shorting the harness does not affect the status on Cat ET. The problem is between the ECM and the harness connector. There may be a problem with the ECM. Proceed to Test Step 7.Test Step 7. Check the Wiring Harness for an Open CircuitNote: This is a continuity test for the signal wire of the sensor circuit in question. This will be done by measuring the resistance of the suspected wire. You will fabricate a jumper wire that will essentially extend the meter lead of the measuring device. This test covers the coolant level sensors for both the engine coolant and the aftercooler coolant. Refer to figures 2 and 3 for the appropriate wire numbers and terminal locations.
Remove electrical power from the ECM.
Disconnect the J2/P2 ECM connector and the connector for the appropriate coolant level sensor.
Fabricate a jumper wire that is long enough to provide a test circuit between the ECM connector and the sensor connector. Crimp a connector pin to one end of the jumper wire.
Install the jumper wire's connector pin into terminal C on the harness side of the connector for the appropriate coolant level sensor.
Measure the resistance between the loose end of the jumper wire and the appropriate P2 connector terminal for the wire under test.Remove the jumper wire. Leave the sensor connector disconnected.Expected Result:The measurement indicates a short circuit.Results:
OK - The measurement indicated a short circuit. There is not an open circuit in the harness wire for the sensor signal. Proceed to Test Step 8.
Not OK - The measurement did not indicate a short circuit.Repair: There is an open circuit or excessive resistance in the harness or the connectors. Repair the wire and/or the connector, when possible. Replace damaged parts, if necessary.STOPTest Step 8. Check the Harness Wiring for a Short Circuit
Remove electrical power from the ECM.
Disconnect the J1/P1 and the J2/P2 ECM connectors. Also, disconnect the connector for the suspect coolant level sensor.
Measure the resistance between the terminal of the appropriate sensor in the first column of Table 1 and the terminals in