Normal Operation and Fault Conditions
The engine cooling system is a closed system providing for coolant expansion and contraction as well as changes in pressure as coolant warms and cools with engine operation. Various gaskets, seals, hoses and clamps contain coolant within the cooling system and keep other fluids and contaminants from entering the cooling system.
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.
Engine coolant flows primarily from the engine to the radiator circuit and back to the electric coolant pump. Coolant is sent from the electric coolant pump through the engine block and cylinder heads. A separate circuit from the engine also feeds the heater core with coolant. The electric coolant pump circulates the coolant. The coolant thermostat is a control valve actuated by coolant temperature. When the thermostat is closed, coolant flow bypasses the radiator circuit and returns to the electric coolant pump. When the thermostat is opened, coolant flows through the radiator circuit to transfer engine-generated heat to the outside air.
Engine overheating generally occurs when there is a disruption in the ability to control either coolant flow at the correct rate, the inability to transfer heat from the engine through the coolant (including low coolant) or an inability to transfer engine-generated heat to the outside air through the radiator.
The engine cooling system maintains 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.
Engine coolant flows primarily from the engine to the radiator circuit and back to the electric coolant pump. Coolant is sent from the electric coolant pump through the engine block and cylinder heads. A separate circuit from the engine also feeds the heater core with coolant. The electric coolant pump circulates the coolant. The coolant thermostat is a control valve actuated by coolant temperature. When the thermostat is closed, coolant flow bypasses the radiator circuit and returns to the electric coolant pump. When the thermostat is opened, coolant flows through the radiator circuit in order to transfer engine generated heat to the outside air.
Concerns of engine inability to reach normal operating temperature typically occur when the rate of coolant flow through some coolant circuits (radiator, heater core) is more than expected given the conditions. Heat is not allowed to build in the engine because a heat exchanger is removing too much heat, including the radiator, heater core and oil cooler. In addition, perceived concerns that the engine does not reach normal operating temperature can be related to a low coolant level or trapped air which does not allow for hot coolant to be available at the heater core, an inoperative climate control system, or for concerns perceived or related to an incorrect engine temperature gauge indication.
REFER to: ENGINE COOLING - SYSTEM OPERATION AND COMPONENT DESCRIPTION .
- Fuses
- Wiring, terminals or connectors
- Electric coolant pump
- PCM
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| P26CA | Engine Coolant Pump Control Circuit Open | When the electric coolant pump module senses no power in the control circuit, it sends a message to the PCM via the LIN. The PCM sets this DTC when the fault is communicated for a predetermined amount of time. |
| P26D0 | Engine Coolant Pump Control Module System Voltage Low | The engine coolant pump control module communicates the control module voltage to the PCM via the LIN . The PCM sets this DTC when the voltage is less than PCM battery voltage minus 4 volts for a predetermined amount of time. |
| P26D1 | Engine Coolant Pump Control Module System Voltage High | The engine coolant pump control module communicates the control module voltage to the PCM via the LIN . The PCM sets this DTC when the voltage is greater than PCM battery voltage plus 4 volts for a predetermined amount of time. |
| P26D3 | Engine Coolant Pump Supply Voltage Circuit | The engine coolant pump control module does not communicate the power and ground circuit status to the PCM . If either of these lines is faulted, the coolant pump will not run and there will be no LIN communication between the engine coolant pump control module and the PCM . The PCM first check for a fault on the LIN . The PCM sets this DTC when the LIN is faulted and the ECT increases more than 10°C (18°F). |
| U019F | Lost Communication With Engine Coolant Pump Control Module | When the PCM does not receive communication from the engine coolant pump control module for a predetermined amount of time, the PCM sets this DTC . |
DTC FAULT TRIGGER CONDITIONS
See also:
• COOLING FAN
• JACKING AND LIFTING - OVERVIEW