LOCK 6B4977 - Caterpillar

Use this procedure to troubleshoot a high coolant temperature. Also, use this procedure if one of the following event codes is active or logged.
Table 1
J1939 Code and Description CDL Code and Description Comments
110-0
Engine Coolant Temperature : High - most severe (3) E361(3)
High Engine Coolant Temperature The engine coolant temperature has exceeded the trip point and the delay time has expired.
Engine power is derated.
The code is logged.
110-15
Engine Coolant Temperature : High - least severe (1) E361(1)
High Engine Coolant Temperature The engine coolant temperature has exceeded the trip point and delay time has expired.
The code is logged.
110-16
Engine Coolant Temperature : High - moderate severity (2) E361(2)
High Engine Coolant Temperature The engine coolant temperature has exceeded the trip point and the delay time has expired.
The code is logged. Probable Causes
Codes
Ambient conditions
Coolant level
Sensor
Connectors and wiring
NOx Reduction System (NRS) Cooler
Relief valve
Temperature regulators
Radiator
Engine cooling fan (if equipped)
Water pump
Personal injury can result from hot coolant, steam and alkali.At operating temperature, engine coolant is hot and under pressure. The radiator and all lines to heaters or the engine contain hot coolant or steam. Any contact can cause severe burns.Remove filler cap slowly to relieve pressure only when engine is stopped and radiator cap is cool enough to touch with your bare hand.Cooling System Conditioner contains alkali. Avoid contact with skin and eyes.
Recommended Actions
Table 2
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Look for active codes that are associated with the system for the event code.
Codes
Result: An associated code is active.
Repair: Troubleshoot any associated codes before continuing with this test.
Result: A code is active or logged.
Proceed to Test Step 2.
2. Verify that the Engine is not Operating in Extreme Ambient Conditions
Ambient Conditions
Result: The engine is not operating in extreme conditions.
Proceed to Test Step 3.
Result: The engine is operating in extreme conditions.
Refer to Operation within the safety section of the Operation and Maintenance Manual (OMM) for the safe operating temperature range.
If the problem is not resolved, proceed to Test Step 3.
3. Check the Coolant Level
Coolant Level
Result: The coolant level is OK. There is no foam or aeration.
Proceed to Test Step 4.
Result: The coolant level is NOT OK.
Repair: Check the cooling system for leaks. Refer to Troubleshooting, "Coolant Level is Low" for additional information. Repair any leaks immediately.
Result: The engine coolant contains foam or aeration.
Repair: Repair the condition that is causing the foam or aeration. Refer to Test and Adjust, "Testing the Cooling System"
If the problem is not resolved, proceed to Test Step 4.
4. Check the Coolant Temperature Sensor
Note: The sensor may be indicating an incorrect temperature that is within the normal range of the sensor.
A. Connect Cat ET.
B. Use Cat ET to monitor the following temperature:
- Coolant temperature
Note: The temperature should rise steadily as the engine is warmed.
C. Ensure that the temperature is reasonable.
D. Reference the reading to another temperature indicator when possible. Refer to Testing and Adjusting, "Testing the Cooling System" for additional information.
Sensor
Result: The temperature sensor is OK.
Proceed to Test Step 6.
Result: The temperature sensor is