SPN 110 - FMI 15 (Event Codes: High Engine Coolant Temperature Warning)

SPN 110 FMI 15

SPN110 FMI15

Status Flags: High Engine Coolant Temp Warning

Figure 1.1 - Eng Cool Temp High (SPN 110 - FMI 15)

Coolant Temperature is High

Use this procedure to troubleshoot High Coolant Temperature or if one of the codes is active.

• E361 (3) = Engine Coolant Temperature High - Most Severe (3). The Engine Coolant Temperature has exceeded the trip point and the delay time has expired. Engine power is derated. The code is logged.
• E361 (2) = Engine Coolant Temperature High - Moderate Severe (2). The Engine Coolant Temperature has exceeded the trip point and delay time has expired. The code is logged.
• E361 (1) = Engine Coolant Temperature High - Least Severe (1). The Engine Coolant Temperature has exceeded the trip point and delay time has expired. The code is logged.

Figure 1.2 - E361 (1) Logged Events

#Probable Causes

• Low Coolant Level and/or Coolant Leakage

• Coolant Temperature Sensor

• Water Temperature Regulator and/or Pressure Relief Valve

• Radiator

• Heat Exchanger

• Engine Cooling Fan (if equipped)

• Coolant Pump

• Cylinder Head Gasket

#Troubleshooting Test Steps:

1). Test Step 1 - Inspect the Engine Coolant Level, and check the Cooling System for leaks. If OK, proceed to Test Step 2.

2). Test Step 2 - Check the Coolant Temperature Sensor and/or the circuit. 

(a). Check the reading of the Coolant Temperature on CAT ET. Read More: How to Connecting Caterpillar ET Software to the ECM. 

(b). The temperature should rise steadily as the engine is warmed. Ensure that the temperature is within operating specifications.

Figure 1.3 - High Engine Coolant Temp Warning (Status Flags)

(c). In this case, the Engine is running about 30 minutes only, then we got a warning: Engine Coolant Temp is High (refer to Figure 1.1 above).

(d). Troubleshoot the circuit and the Coolant Temperature Sensor:

→Disconnect the Coolant Temperature Sensor at the sensor connector (keyswitch: ON position).

→Measure the voltage between terminal 1 (sensor signal) and terminal 2 (sensor return) at the sensor connector. In this case, pull-up voltage is OK (the voltage is 5.5 ± 0.5 VDC). Read More: PULL-UP Voltage and How the ECM Uses it to Determine Diagnostic Conditions. Also, check for active Diagnostic Codes -03 (110-3), or Voltage Above Normal.

Figure 1.4 - Voltage Above Normal (110-3)

(e). Create a Short at the Engine Coolant Temperature Sensor connector (keyswitch: ON position).

→Check for active Diagnostic Codes -04 (110-4), or Voltage Below Normal. In this case, the engine harness and the ECM are OK. Read More: Sensor Diagnostics on Electronic Engines.

Figure 1.5 - Voltage Below Normal (110-4)

(f). Measuring the resistance of the sensor (50 ohms only). Replace the Engine Coolant Temperature Sensor, with CAT P/N: 234-5012. If the temperature sensor is OK, proceed to Test Step 3.

3). Test Step 3 - Check the Water Temperature Regulator and/or Pressure Relief Valve.

(a). Pressure-test the cooling system.

(b). Check that the seating surfaces of the pressure relief valve and the radiator cap are clean and undamaged.

(c). Check operation of the pressure relief valve and/or the water temperature regulator.

→Clean the components and/or replace the components.

→If the problem is not resolved, proceed to Test Step 4.

4). Test Step 4 - Inspect the Radiator.

(a). Check the radiator fins for dirt, debris, and/or damage.

(b). Check for collapsed hoses and/or other restrictions.

(c). Check the radiator for internal blockage.

→Remove any dirt and/or debris and straighten any bent fins.

→If the problem is not resolved, proceed to Test Step 5.

5). Test Step 5 - Check the Heat Exchanger for Sufficient Flow.

(a). Check for sufficient flow and temperature of the cooling water through the heat exchanger.

→Determine the location of the obstruction. If the temperature of the cooling water is too high, determine the cause. Ensure that the size of the heat exchanger is sufficient. Make the necessary repairs.

→If the problem is not resolved, proceed to Test Step 6.

6). Test Step 6 - Faulty Engine Cooling Fan (if equipped).

(a). If the fan is belt driven, check for loose drive belts.

(b). Check the fan clutch, if equipped.

→A loose fan drive belt will cause a reduction in the air flow across the radiator.

→Adjust the tension of the fan drive belt, if necessary.

→If the problem is not resolved, proceed to Test Step 7.

7). Test Step 7 - Inspection of the Coolant Pump.

(a). Inspect the impeller of the coolant pump for damage and/or erosion.

(b). Make sure that the drive gear is not loose on the drive shaft of the coolant pump.

→If necessary, replace the coolant pump.

→If the problem is not resolved, proceed to Test Step 8.

8). Test Step 8 - Inspect the Cylinder Head Gasket.

(a). Remove the cylinder head.

(b). Check the cylinder liner projection.

(c). Pressure test the head for leaks.

(d). Install a new cylinder head gasket and new water seals in the spacer plate.

#Trip points for the Monitoring System

The Monitoring System determines the level of action that is taken by the Electronic Control Module

(ECM) in response to a condition that can damage the Engine. When any of these conditions occur,

the appropriate Event Code will trip.

Figure 1.6 - High Engine Coolant Temperature (Monitoring System)

Read More:

Speed Control on Caterpillar Engines

CAN Bus Failure on Engine's Display

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