BREATHER GP 2429946 - Caterpillar

Remove electrical power from the ECM.Note: Allow the engine to cool prior to removal of the cooling system pressure cap.
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 5.
Not OK - The coolant level is low.Repair: Add coolant according to the procedure in the Operation and Maintenance Manual.There may be a leak in the cooling system. Identify the source of the coolant leak. Repair the leak.STOPTest Step 5. Disconnect the Coolant Level Sensor and Monitor the Status for "Coolant Level"
Disconnect the harness connector for the coolant level sensor.
Restore electrical power to the ECM.
Monitor the status of "Coolant Level" on Cat ET.Note: Wait at least 30 seconds for activation of the status indicator.
Remove electrical power from the ECM.Expected Result:The status changes from "OK" to "LOW" when the sensor is disconnected.Results:
OK - The status is "LOW" when the sensor is disconnected. There may be a problem with the coolant level sensor. Proceed to Test Step 6.
Not OK - The status is "OK" when the sensor is disconnected. 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 6. Short the Signal Wire to Ground and Monitor the Status for "Coolant Level"
Fabricate a jumper wire that is long enough to create a short circuit between two terminals at the coolant level sensor's harness connector. Crimp connector pins to each end of the jumper wire.
Install the jumper wire between terminals B (sensor return) and C (sensor signal) on the harness side of the connector for the coolant level sensor.
Restore electrical power to the ECM.
Monitor the status of "Coolant Level" on Cat ET while the jumper wire is installed.Note: Wait at least 30 seconds for activation of the status indicator.
Remove electrical power from the ECM.
Remove the jumper wire. Connect the harness connector for the coolant level sensor.Expected Result:The status changes from "LOW" to "OK" when the jumper wire is installed.Results:
OK - The status changes from "LOW" to "OK" when the jumper wire is installed. The ECM and the wiring harness to the coolant level sensor are OK.Repair: Perform the following procedure:
Restore electrical power to the ECM.
Monitor the status of "Coolant Level" on Cat ET.Note: Wait at least 30 seconds for activation of the status indicator.If the status of the "Coolant Level" is "OK", continue with this procedure.If the status for the coolant level is "LOW", there may be an intermittent problem in the harness or in a connector. If an intermittent electrical problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect" for troubleshooting information. If there is no problem in the harness, replace the coolant level sensor.
Remove electrical power from the ECM.
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.