Pinpoint Test B: The Engine Overheats

Normal Operation and Fault Conditions

The engine cooling system maintains the engine temperature during operation. Correct coolant flow through the engine, radiator and remainder of cooling system passages and components is essential to maintaining a correct engine temperature.

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
PCM P26D2:00	Engine Coolant Pump Control Module Over Temperature: No Sub Type Information	Sets in the PCM when an engine overheat condition was sensed by the CHT sensor.
PCM P1299:00	Cylinder Head Overtemperature Protection Active: No Sub Type Information	Sets in the PCM when an engine overheat condition was sensed by the CHT sensor.
PCM P0217:00	Engine Coolant Overtemperature Condition: No Sub Type Information	Sets in the PCM when an engine overheat condition was sensed by the CHT sensor.

Possible Sources

Low coolant level
External engine coolant leak
Airlock in system
Pressure relief cap installation
Restricted airflow through A/C condenser/radiator
Internal engine coolant leak
Coolant condition/concentration
Non-OEM engine enhancement components
Electric cooling fan
CHT sensor
Radiator
Thermostat
Coolant pump
Coolant flow restriction
Active grill shutter assembly

B1 CARRY OUT INSPECTION AND VERIFICATION
- Carry out the Inspection and Verification procedure in this service information.
Are any concerns present?

Yes REPAIR as needed.

No GO to B2

B2 CHECK FOR PCM (POWERTRAIN CONTROL MODULE) DTCS

Ignition ON.

Using a scan tool, perform PCM self-test.

Is DTC P0217 and/or P1299 present?

Yes

GO to B4

No	Actual engine overheating has not been verified. CHECK the engine coolant temperature gauge operation. REFER to: Instrumentation, Message Center and Warning Chimes . If any other PCM DTCs are retrieved, REFER to: Electronic Engine Controls .

B3 CHECK FOR ACTIVE GRILL SHUTTER DTCS
- Review the PCM DTCs.
Are any active grill shutter DTCs present?

Yes REFER to: Active Grille Shutter .

No GO to B4

B4 CHECK FOR AN AIRFLOW OBSTRUCTION AND MISSING AIR DEFLECTORS

NOTE: Verify no vehicle front end damage is present.
- Check the radiator or A/C condenser for an external obstruction such as leaves or cardboard and verify all air deflectors are present.
Is an airflow obstruction present or air deflectors missing?

Yes REPAIR as necessary.

No GO to B5

B5 CHECK THE ENGINE COOLANT LEVEL AND PRESSURE TEST THE COOLING SYSTEM
- Ignition OFF.
- Visually check the engine coolant level in the coolant expansion tank and adjust as necessary. Pressure test the cooling system.
Does the engine cooling system leak externally?

Yes REPAIR or INSTALL new components.

No GO to B6

B6 CHECK THE ENGINE COOLANT FOR AN INTERNAL LEAK
- Inspect the engine coolant in the coolant expansion tank for signs of engine oil.
Is engine oil evident in the coolant?

Yes REFER to: Engine .

No GO to B7

B7 CHECK THE ENGINE OIL FOR COOLANT
- Remove the oil level indicator from the engine.
Is coolant evident in the oil?

Yes REFER to: Engine .

No GO to B8

B8 CHECK THE ENGINE COOLANT FOR TRANSMISSION FLUID

Check the engine coolant in the degas bottle for signs of transmission fluid.

Is transmission fluid evident in the engine coolant?

Yes	INSTALL a new transmission fluid cooler. REFER to: Transmission Fluid Cooler . REPAIR the transmission as necessary. REFER to: Automatic Transmission TEST the system for normal operation.

GO to B9

B9 CHECK THE TRANSMISSION FLUID FOR ENGINE COOLANT

Remove the transmission oil leveling plug.

Check the transmission fluid for engine coolant.

Is engine coolant evident in the transmission fluid?

Yes	INSTALL a new transmission fluid cooler. REFER to: Transmission Fluid Cooler . REPAIR the transmission as necessary. REFER to: Automatic Transmission TEST the system for normal operation.

GO to B10

B10 CHECK THE COOLING SYSTEM FOR COMBUSTION GASES

NOTE: Use UView® Combustion Leak Tester part number UVU560000-R or equivalent.
- Using a cooling system combustion gas leak tester, following the instructions supplied with the tester, check the coolant for combustion gases.
Are combustion gases present?

Yes REFER to: Engine .

No GO to B11

B11 CHECK COOLANT CONDITION
- Check the coolant for dirt, rust or contamination and check the coolant concentration.
Is the coolant condition OK?

Yes GO to B12

No FLUSH the engine cooling system. REFER to: Engine Cooling System Flushing .

B12 CHECK THE ELECTRIC COOLING FAN OPERATION
- Start the engine.
- Place the climate control function selector in the MAX A/C position and the blower motor switch in the HI position.
Did the electric cooling fan operate?

Yes GO to B13

No DIAGNOSE the electric cooling fan operation. REFER to: Cooling Fan Control .

B13 CHECK THE COOLANT PUMP OPERATION
- Start the engine.
- Allow the engine to run for 30 minutes. Place the climate control function selector in the MAX HEAT position. Feel the heater outlet hose.
Is the heater outlet hose hot?

Yes GO to B14

No INSTALL a new coolant pump. REFER to: Coolant Pump .

B14 CHECK THE THERMOSTAT OPERATION

NOTE: This cooling system uses a cold side thermostat. The coolant in the radiator must reach full operating temperature for the thermostat to remain in an open state.
- Start the engine.
- Allow the engine to run for 30 minutes. Place the climate control function selector in the MAX HEAT position. Feel the lower radiator hose.
Is the lower radiator hose hot?

Yes CHECK the temperature gauge operation. REFER to: Instrumentation, Message Center and Warning Chimes .

No GO to B15

B15 VISUALLY INSPECT THE THERMOSTAT

Carry out the Thermostat Visual Inspection in Thermostat .

Is the thermostat damaged?

Yes	INSTALL a new thermostat. REFER to: Thermostat Housing .

No	INSTALL a new thermostat. REFER to: Thermostat Housing . If the engine still overheats, INSTALL a new radiator. REFER to: Radiator .