Pinpoint Test C: The Engine Does Not Reach Normal Operating Temperature

Powertrain Secondary Cooling System

Pinpoint Tests

Pinpoint Test C: The Engine Does Not Reach Normal Operating Temperature

Normal Operation

The secondary cooling system maintains temperatures in the Charge Air Cooler (CAC), the fuel cooler, the transmission cooler and the EGR cooler during operation. Correct coolant flow through the radiator and the remaining components of the system is essential to maintaining correct temperatures.

Coolant flows primarily from the coolant pump to the radiator circuit and then to the transmission fluid cooler and EGR cooler from the high temperature thermostat and the CAC and the fuel cooler from the low temperature thermostat. The coolant flows from each component to the degas bottle and then back to the coolant pump. The coolant pump is operated by engine rotation through a pulley which is driven by the accessory drive belt to circulate the coolant. The coolant thermostats are control valves actuated by coolant temperature. When the thermostats are closed, coolant flow bypasses the radiator circuit and flows to the 4 cooling components. When the thermostats are opened, coolant is allowed to flow through the radiator circuit in order to transfer component-generated heat to the outside air.

Concerns of an inability to reach normal operating temperature typically occur when the rate of coolant flow through the radiator is more than expected given the conditions. Heat is not allowed to build in the system because a heat exchanger is removing too much heat, including the radiator, CAC, fuel cooler, EGR cooler or transmission fluid cooler.

- DTC P007C ( CACT Sensor Circuit Low) - Indicates a lower than expected air temperature as the air flows out of the CAC.
- DTC P2184 (Engine Coolant Temperature (ECT) Sensor 2 Circuit Low) - Indicates lower than expected coolant temperature as the coolant flows into the EGR cooler.

This pinpoint test is intended to diagnose the following:
- Low coolant level
- Thermostat

PINPOINT TEST C: THE SECONDARY COOLING SYSTEM DOES NOT REACH NORMAL OPERATING TEMPERATURE

WARNING: Always allow the engine to cool before opening the cooling system. Do not unscrew the coolant pressure relief cap when the engine is operating or the cooling system is hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions may result in serious personal injury.

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C1 CARRY OUT INSPECTION AND VERIFICATION

- Carry out the Inspection and Verification procedure. Inspection and Verification
- Were any concerns found?

Yes
REPAIR as needed. TEST the system for normal operation.

No
GO to C2 .

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C2 CHECK FOR DTCs P007C or P2184

- Check for DTCs P007C or P2184.
- Is DTC P007C or P2184 present?

Yes
GO to C3 .

No
The cooling system is operational.

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C3 CHECK THE COOLANT LEVEL

- NOTE: Allow the engine to cool before checking the coolant level.

- Visually check the coolant level in the degas bottle.
- Is the coolant level within specification?

Yes
INSTALL a new low temperature thermostat and a new high temperature thermostat. REFER to Thermostat - Low Temperature Powertrain Secondary Cooling System - Thermostat - Low Temperature and Thermostat - High Temperature Powertrain Secondary Cooling System - Thermostat - High Temperature. TEST the system for normal operation.

No
GO to Pinpoint Test A to diagnose a coolant leak. Pinpoint Test A: Loss of Coolant

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