3516B and 3516C Engines For MT4400D AC Off-Highway Trucks Caterpillar

Use this procedure in order to troubleshoot a low coolant temperature. Or, use this procedure if one of the following event codes is active.

Table 1

Event Codes
Code and Description	Conditions which Generate this Code	System Response
110-17 Engine Coolant Temperature : Low - least severe (1)	The temperature of the engine coolant has fallen below the trip point for the programmed delay time.	The code is logged. The ECM may derate the engine or shutdown the engine.
110-18 Engine Coolant Temperature : Low - moderate severity (2)
110-1 Engine Coolant Temperature : Low - most severe (3)
E199(1) Low Coolant Temperature - least severe	The temperature of the engine coolant has fallen below the trip point for the programmed delay time.	The code is logged. The ECM may derate the engine or shutdown the engine.
E199(2) Low Coolant Temperature - moderate severity
E199(3) Low Coolant Temperature - most severe

Probable Causes

• Ambient temperatures (if applicable)

• Loads (if applicable)

• Engine speed

• Cooling fan

• Water temperature regulator

• Temperature sensor

Recommended Actions

Note: The procedures have been listed in order of probability. Complete the procedures in the order of the listed test steps.

Table 2

Troubleshooting Test Steps	Values	Results
1. Extreme Ambient Temperatures (if applicable) A. Extreme ambient temperature can cause overcooling.	Extreme ambient temperatures	Result: Ambient temperatures are extreme. Repair: Install winter covers. Verify that the repair eliminates the problem. Result: Ambient temperatures are not extreme. Proceed to Test Step 2.
2. Load Factor (if applicable) A. Light loads can cause overcooling. This overcooling is caused by the low heat input of the engine.	Light loads	Result: Engine is operating under a light load. Repair: Increase load factor if possible. Verify that the repair eliminates the problem. Result: Engine is not operating under a light load. Proceed to Test Step 3.
3. Low Engine Speed A. Low engine speed can cause overcooling.	Low engine speed	Result: Engine is running at a low speed. Repair: Increase engine speed if possible. Verify that the repair eliminates the problem. Result Engine is not running at a low speed. Proceed to Test Step 4.
4. The Cooling Fan is Always On A. If the cooling fan is always on, overcooling can occur.	Fan always on	Result The cooling fan is always on. Repair: Resolve the issue. Verify that the repair eliminates the problem. Result The cooling fan is not always on. Proceed to Test Step 5.
5. Water Temperature Regulator A regulator that is stuck open can cause overcooling. A. Test the water temperature regulator according to Testing and Adjusting, "Water Temperature Regulator - Test". B. Make sure that the proper water temperature regulator is installed. Refer to the Specifications manual for the correct water temperature regulator.	Water temperature regulator	Result The regulator is stuck open or not installed. Repair: Replace the regulator. Verify that the repair eliminates the problem. Result The regulator not is stuck open is installed. Proceed to Test Step 6.
6. Faulty Coolant Temperature Sensor and/or Circuit A. Check the reading of the coolant temperature on the Cat ET. The temperature should rise steadily as the engine is warmed. Ensure that the temperature is reasonable.	Faulty sensor or circuit	Result The coolant temperature is not reasonable. Repair: Troubleshoot the circuit and the coolant temperature sensor. Refer to Troubleshooting, "Sensor Signal (Analog, Passive) - Test". Verify that the repair eliminates the problem. Result The coolant temperature is reasonable. STOP

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).