C175 Tier 4 Final Engines for Off-Highway Trucks Caterpillar

Coolant Temperature Is Low

Usage:

793F D3T

Use this procedure to troubleshoot a low engine coolant temperature or use this procedure if the following event code is active.

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Table 1
J1939 Code and Description	CDL Code and Description	System Response
110-1 Engine Coolant Temperature : Low - most severe (3)	E199(1) Low Coolant Temperature	The engine coolant temperature is below the trip point temperature for the programmed delay time. The code is logged.
110-17 Engine Coolant Temperature : Low - least severe (1)	E199 (1) Low Coolant Temperature	The coolant temperature did not rise above a temperature threshold after an extended period of operation under load.
110-18 Engine Coolant Temperature : Low - moderate severity (2)	E199 (2) Low Coolant Temperature	The coolant temperature did not rise above a temperature threshold after an extended period of operation under load.

Probable Causes

Diagnostic codes and event codes
Light loads
Temperature Control Module (TCM)

Recommended Actions

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Connect Cat^® Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Download the "Product Status Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes. C. Determine if the diagnostic trouble code that directed to this procedure is present. D. Look for active diagnostic codes that are associated with the system for the event code that directed to this procedure.	E199	Result: An associated code is present. Repair: Troubleshoot any associated codes before continuing with this test. Result: An E199 code is present. Proceed to the next step. Result: No active codes STOP
2. Check for Light Loads A. Consult the operator to determine the usual load factor.	Load	Result: The load factor is OK. Proceed to the next step. Result: The load factor is less than 50% NOT OK. Note: This overcooling is caused by the reduced amount of heat that is produced by the engine during light loads. Repair: Operate the engine at a load that is greater than 50%. If the problem is not resolved, proceed to the next step.

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Illustration 1	g01320751
Connector locations for the temperature control module (1) 8-pin connector for the motor assembly and the communications device (2) 12-pin connector for the engine harness

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Illustration 2	g02554619
Removing the inspection cover from the motor assembly (3) Main shaft extension (4) Plug and O-ring seal

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Illustration 3	g01321224

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Table 3
Troubleshooting Test Steps	Values	Results
3. Check the Temperature Control Module A. Perform the following procedure: 1. Visually inspect the wiring from the temperature control module to the coolant temperature sensor and from the temperature control module to the power supply. Visually inspect the 12-pin connector and the 8-pin connector at the temperature control module. Check for a tight connection at the connectors. B. Check for proper operation of the temperature control module: 1. Ensure that the keyswitch is in the OFF position. Turn the electrical disconnect to the OFF position. 2. Remove plug (4) from the motor assembly. Remove the inspection cover from the motor. 3. Use the appropriate wrench to rotate the main shaft extension. Ensure that the shaft rotates freely. Rotate the shaft to ensure that the piston is not positioned at one of the end stops of the valve. 4. Visually inspect main shaft extension (3) for rotation while you establish power to the ECM and to the keyswitch circuit. The shaft will rotate several times during the powerup sequence. 5. During the powerup sequence, listen for the valve to travel to the end stop. Listen for the piston to hammer the end stop to establish the valve position. 6. With the keyswitch and the electrical disconnect in the ON position, disconnect the engine harness connector (12-pin connector) at the controller. Diagnostic codes will become active for the valve. 7. Use a wrench to rotate the main shaft extension to position the valve piston away from the end stop of the valve. 8. Connect the connector and observe the motor assembly. The valve will repeat the power-up sequence when the engine harness (power) is connected. While you connect the connector, check the main shaft extension for rotation. The valve will hammer at the end stop. 9. Turn the keyswitch and electrical disconnect to the OFF position. Replace the inspection cover and connect all connectors. C. Disconnect the engine harness connector (12-pin connector) at the temperature control module. D. Measure the battery voltage between terminal 1 (+Battery) and terminal 5 (return) on the harness side of the 12-pin connector. The supply voltage for the control module must be between 18 VDC and 32 VDC. E. Restore the wiring to the original configuration.	The Connectors and Wiring, Operation of TCM, and 18 V - 32 V	Result: The connectors and wiring are OK. Continue with this step. Result: The connectors and wiring are NOT OK. Repair: Or replace as necessary. Continue with this step. Result: The TCM is OK. Continue with this step. Result: The TCM is NOT OK. Repair: If the piston binds during travel, disassemble and inspect the motor mount to determine the cause of the binding. Do not apply excessive force to the main shaft extension. Extensive damage to the shaft bearings may occur. Refer to Disassembly and Assembly, "Thermostatic Valve - Disassemble" for disassembly instructions. Note: The TCM may be operated in a manual mode by disconnecting the 8-pin connector for the motor assembly from the TCM. The valve may be manually positioned by using a wrench on the main shaft extension. This method could be used to diagnose problems with other cooling system components. Disconnecting the connector for the motor assembly will not activate diagnostic codes for the TCM. Result: The supply voltage for the TCM is between 18 VDC and 32 VDC. Result: The supply voltage for the TCM is not between 18 VDC and 32 VDC. Repair: Or replace as necessary. If the problem has not been resolved, consult your technical communicator (TC) for further instructions.