NHTSA ID Number: 10146323
Manufacturer Communication Number: 0502-18
TSB/Document Date: 2018-10-29
Summary
0502-18 Symptom Diagnostics - Low Engine Coolant Temperature
05 02-18
1
05 02-18
SUBJECT
DATE
Symptom Diagnostics - Low Engine Coolant Temperature
May 2018
Additions, Revisions, or Updates
Publication Number / Title
DDC-SVC-MAN-0084
DDC-SVC-MAN-0191
Platform
Section Title
Change
DD13,
DD15,
DD16
Low Engine Coolant
Temperature
Added clarification to complaint verification and added link to
remove the thermostat prior to inspecting the thermostat.
DD5, DD8
Low Engine Coolant
Temperature
Added clarification to complaint verification, added link to remove
the thermostat prior to inspecting the thermostat and updated
temperature specifications.
DDC-SVC-MAN-0193
DDC-SVC-MAN-0200
DiagnosticLink users: Please update the troubleshooting guides in DiagnosticLink with this newest version. To update the
tool troubleshooting guide, open DiagnosticLink and from the Help – Troubleshooting Guides menu, select the appropriate
troubleshooting manual, then click Update.
All information subject to change without notice.
05 02-18
Copyright © 2018 DETROIT DIESEL CORPORATION
3
2 Low Engine Coolant Temperature
2
Low Engine Coolant Temperature
WARNING: PERSONAL INJURY
Diesel engine exhaust and some of its constituents are known to the State of California to cause
cancer, birth defects, and other reproductive harm.
• Always start and operate an engine in a well ventilated area.
• If operating an engine in an enclosed area, vent the exhaust to the outside.
• Do not modify or tamper with the exhaust system or emission control system.
WARNING: PERSONAL INJURY
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level
surface, parking brake is set, and the wheels are blocked.
Check as follows:
NOTE: In extremely cold ambient temperatures, it may take longer than 20 minutes of driving to reach operating
temperature. In these cases, performing a Parked Regeneration is preferred.
NOTE: Use DiagnosticLink ® to monitor engine coolant temperature.
1. Verify the complaint by driving the vehicle for 20 minutes or performing a Parked Regeneration. Does the engine
coolant temperature reach and maintain a minimum of 85°C (185°F)?
a. Yes; the vehicle is performing as intended; no further troubleshooting is required. Shut down the engine.
b. No; shut down the engine. Go to step 2.
NOTE: If there is no heat in the cab but the engine temperature does rise to normal operating temperature,
diagnose the Heating Ventilation and Air Conditioning (HVAC) system.
2. Check engine coolant fan operation. Does the fan function and cycle correctly?
a. Yes; Go to step 3.
b. No; diagnose the engine fan operation.
3. Inspect the vehicle for aftermarket cooling system components plumbed into the engine cooling system. Are any
aftermarket cooling system components present?
a. Yes; Go to step 4.
b. No; Go to step 5.
NOTE: Use DiagnosticLink ® to monitor engine coolant temperature.
4. Bypass the aftermarket cooling system component and verify the complaint by driving the vehicle for 20 minutes or
performing a Parked Regeneration. Does the engine coolant temperature reach and maintain a minimum of 85°C
(185°F)?
a. Yes; no further engine troubleshooting is required. Shut down the engine. Troubleshoot the aftermarket cooling
system component.
b. No; Go to step 5.
5. Remove the thermostat. Refer to section "Removal of the Engine Coolant Thermostat and Seal".
6. Inspect the thermostat. Refer to section "Inspection of the Coolant Thermostat and Seal". Is the thermostat faulty or
damaged?
a. Yes; replace the thermostat. Refer to section "Removal of the Engine Coolant Thermostat and Seal". Verify
repair.
4
All information subject to change without notice.
Copyright © 2018 DETROIT DIESEL CORPORATION 05 02-18
05 02-18
b. No; review the results of the above troubleshooting steps to see if all results are consistent and accurate.
Replace the thermostat. Refer to section "Removal of the Engine Coolant Thermostat and Seal". Verify repair.
All information subject to change without notice.
05 02-18
Copyright © 2018 DETROIT DIESEL CORPORATION
5
3 Low Engine Coolant Temperature
3
Low Engine Coolant Temperature
WARNING: PERSONAL INJURY
Diesel engine exhaust and some of its constituents are known to the State of California to cause
cancer, birth defects, and other reproductive harm.
• Always start and operate an engine in a well ventilated area.
• If operating an engine in an enclosed area, vent the exhaust to the outside.
• Do not modify or tamper with the exhaust system or emission control system.
WARNING: PERSONAL INJURY
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level
surface, parking brake is set, and the wheels are blocked.
Check as follows:
NOTE: In extremely cold ambient temperatures, it may take longer than 20 minutes of driving to reach operating
temperature. In these cases, performing a Parked Regeneration is preferred.
NOTE: Use DiagnosticLink ® to monitor engine coolant temperature.
1. Verify the complaint by driving the vehicle for 20 minutes or performing a Parked Regeneration. Does the engine
coolant temperature reach and maintain a minimum of 85°C (185°F)?
a. Yes; the vehicle is performing as intended; no further troubleshooting is required. Shut down the engine.
b. No; shut down the engine. Go to step 2.
NOTE: If there is no heat in the cab but the engine temperature does rise to normal operating temperature,
diagnose the Heating Ventilation and Air Conditioning (HVAC) system.
2. Check engine coolant fan operation. Does the fan function and cycle correctly?
a. Yes; Go to step 3.
b. No; diagnose the engine fan operation.
3. Inspect the vehicle for aftermarket cooling system components plumbed into the engine cooling system. Are any
aftermarket cooling system components present?
a. Yes; Go to step 4.
b. No; Go to step 5.
NOTE: Use DiagnosticLink ® to monitor engine coolant temperature.
4. Bypass the aftermarket cooling system component and verify the complaint by driving the vehicle for 20 minutes or
performing a Parked Regeneration. Does the engine coolant temperature reach and maintain a minimum of 85°C
(185°F)?
a. Yes; no further engine troubleshooting is required. Shut down the engine. Troubleshoot the aftermarket cooling
system component.
b. No; Go to step 5.
5. Remove the thermostat. Refer to section "Removal of the Engine Coolant Thermostat and Seal".
6. Inspect the thermostat. Refer to section "Inspection of the Coolant Thermostat and Seal". Is the thermostat faulty or
damaged?
a. Yes; replace the thermostat. Refer to section "Removal of the Engine Coolant Thermostat and Seal". Verify
repair.
6
All information subject to change without notice.
Copyright © 2018 DETROIT DIESEL CORPORATION 05 02-18
05 02-18
b. No; review the results of the above troubleshooting steps to see if all results are consistent and accurate.
Replace the thermostat. Refer to section "Removal of the Engine Coolant Thermostat and Seal". Verify repair.
All information subject to change without notice.
05 02-18
Copyright © 2018 DETROIT DIESEL CORPORATION
7
4 Low Engine Coolant Temperature
4
Low Engine Coolant Temperature
WARNING: PERSONAL INJURY
Diesel engine exhaust and some of its constituents are known to the State of California to cause
cancer, birth defects, and other reproductive harm.
• Always start and operate an engine in a well ventilated area.
• If operating an engine in an enclosed area, vent the exhaust to the outside.
• Do not modify or tamper with the exhaust system or emission control system.
WARNING: PERSONAL INJURY
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level
surface, parking brake is set, and the wheels are blocked.
Check as follows:
NOTE: In extremely cold ambient temperatures, it may take longer than 20 minutes of driving to reach operating
temperature. In these cases, performing a Parked Regeneration is preferred.
NOTE: Use DiagnosticLink ® to monitor engine coolant temperature.
1. Verify the complaint by driving the vehicle for 20 minutes or performing a Parked Regeneration. Does the engine
coolant temperature reach and maintain a minimum of 83°C (181°F)?
a. Yes; the vehicle is performing as intended, no further troubleshooting is required. Shut down the engine.
b. No; shut down the engine. Go to step 2.
NOTE: If there is no heat in the cab but the engine temperature does rise to normal operating temperature,
diagnose the Heating Ventilation and Air Conditioning (HVAC) system.
2. Check engine coolant fan operation. Does the fan function and cycle correctly?
a. Yes; Go to step 3.
b. No; diagnose the engine fan operation.
3. Inspect the vehicle for aftermarket cooling system components plumbed into the engine cooling system. Are any
aftermarket cooling system components present?
a. Yes; Go to step 4.
b. No; Go to step 5.
NOTE: Use DiagnosticLink ® to monitor engine coolant temperature.
4. Bypass the aftermarket cooling system component and verify the complaint by driving the vehicle for 20 minutes or
performing a Parked Regeneration. Does the engine coolant temperature reach and maintain a minimum of 83°C
(181°F)?
a. Yes; no further engine troubleshooting is required. Shut down the engine. Troubleshoot the aftermarket cooling
system component.
b. No; Go to step 5.
5. Remove the thermostat. Refer to section "Removal of the Coolant Thermostat".
6. Inspect the thermostat. Refer to section "Inspection of the Coolant Thermostat". Is the thermostat faulty or damaged?
a. Yes; replace the thermostat. Refer to section "Removal of the Coolant Thermostat". Verify repair.
b. No; review the results of the above troubleshooting steps to see if all results are consistent and accurate.
Replace the thermostat. Refer to section "Removal of the Coolant Thermostat". Verify repair.
8
All information subject to change without notice.
Copyright © 2018 DETROIT DIESEL CORPORATION 05 02-18
05 02-18
5
Low Engine Coolant Temperature
WARNING: PERSONAL INJURY
Diesel engine exhaust and some of its constituents are known to the State of California to cause
cancer, birth defects, and other reproductive harm.
• Always start and operate an engine in a well ventilated area.
• If operating an engine in an enclosed area, vent the exhaust to the outside.
• Do not modify or tamper with the exhaust system or emission control system.
WARNING: PERSONAL INJURY
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level
surface, parking brake is set, and the wheels are blocked.
Check as follows:
NOTE: In extremely cold ambient temperatures, it may take longer than 20 minutes of driving to reach operating
temperature. In these cases, performing a Parked Regeneration is preferred.
NOTE: Use DiagnosticLink ® to monitor engine coolant temperature.
1. Verify the complaint by driving the vehicle for 20 minutes or performing a Parked Regeneration. Does the engine
coolant temperature reach and maintain a minimum of 83°C (181°F)?
a. Yes; the vehicle is performing as intended, no further troubleshooting is required. Shut down the engine.
b. No; shut down the engine. Go to step 2.
NOTE: If there is no heat in the cab but the engine temperature does rise to normal operating temperature,
diagnose the Heating Ventilation and Air Conditioning (HVAC) system.
2. Check engine coolant fan operation. Does the fan function and cycle correctly?
a. Yes; Go to step 3.
b. No; diagnose the engine fan operation.
3. Inspect the vehicle for aftermarket cooling system components plumbed into the engine cooling system. Are any
aftermarket cooling system components present?
a. Yes; Go to step 4.
b. No; Go to step 5.
NOTE: Use DiagnosticLink ® to monitor engine coolant temperature.
4. Bypass the aftermarket cooling system component and verify the complaint by driving the vehicle for 20 minutes or
performing a Parked Regeneration. Does the engine coolant temperature reach and maintain a minimum of 83°C
(181°F)?
a. Yes; no further troubleshooting is required. Shut down the engine. Troubleshoot the aftermarket cooling system
component.
b. No; Go to step 5.
5. Remove the thermostat. Refer to section "Removal of the Coolant Thermostat".
6. Inspect thermostat for correct operation. Refer to section "Inspection of the Coolant Thermostat". Is the thermostat
faulty or damaged?
a. Yes; replace the thermostat. Refer to section "Removal of the Coolant Thermostat". Verify repair.
All information subject to change without notice.
05 02-18
Copyright © 2018 DETROIT DIESEL CORPORATION
9
5 Low Engine Coolant Temperature
b. No; review the results of the above troubleshooting steps to see if all results are consistent and accurate.
Replace the thermostat. Refer to section "Removal of the Coolant Thermostat". Verify repair.
10
All information subject to change without notice.
Copyright © 2018 DETROIT DIESEL CORPORATION
05 02-18
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TSB/Document ID: 0502-18
Replacement Service Bulletin Number:
MFR Communication Date: 2018-05-02
MFR Internal Campaign ID/Software Version:
Communication Type: Service Bulletin/Repair Instructions
NHTSA Components: ENGINE AND ENGINE COOLING
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