Chevrolet Trax: DTC P2181 (2H0 OR LUJ): Engine cooling system performance

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P2181

Engine Cooling System Performance

Circuit/System Description

The engine control module (ECM) monitors temperature difference between the engine coolant temperature (ECT) sensor and the radiator coolant temperature (RCT) sensor during a cold start-up. The purpose of this diagnostic is to analyze the engine coolant thermostat for being stuck open.

Conditions for Running the DTC

• DTCs P00B3, P00B4, P00B6, P0101, P0102, P0103, P0111, P0112, P0113, P0114, P0116, P0117, or P0118 are not set.
• The engine run time is between 70 s and 30 min.
• The engine coolant temperature (ECT) sensor at start-up is between -10ºC to +59ºC (14ºF to 138ºF).
• The intake air temperature (IAT) sensor is between -7ºC to +60ºC (-4ºF to +140ºF).
• The airflow into the engine is between 1 to 100 g/s.
• The DTC runs once per ignition cycle when the above conditions are met.

Conditions for Setting the DTC

The ECM detects the engine coolant thermostat is stuck open for at least 2.5 min.

Action Taken When the DTC Sets

DTC P2181 is a Type B DTC

Conditions for Clearing the DTC

DTC P2181 is a Type B DTC

Diagnostic Aids

• Insufficient vehicle interior heating is an indication of improper thermostat operation.
• The scan tool Desired ECT Sensor and the ECT Sensor parameters should be within 5ºC (9ºF) when the engine is at operating temperature.
• A resistance condition in the ECT sensor circuits may cause this DTC. This condition results in a greater voltage on the ECT sensor signal circuit, which is interpreted by the ECM as a colder ECT

Reference Information

Schematic Reference

Engine Heating/Cooling Schematics (Encore), Engine Heating/Cooling Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Engine running, observe the DTC information with a scan tool. DTC P00B3, P00B4, P00B6, P0117, or P0118 should not be set.

• If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

2. Verify the coolant in the radiator surge tank is at the correct level and there are no engine coolant leaks.

   Refer to Cooling System Draining and Filling, and Loss of Coolant.

NOTE: Depending on ambient temperature, it may take up to 4 min for the temperature to increase greater than the specified value.

3. Engine idling for 15 min with the A/C OFF. Verify the engine cooling fan is not ON at all times.
4. Command the Engine Coolant Thermostat Heater to 0 % with a scan tool. Increase the engine speed to 3,000 RPM. Observe the scan tool ECT sensor parameter. The temperature should increase to greater than 102ºC (215ºF).

• If less than the specified value, replace the E41 engine coolant thermostat heater.

5. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Engine Coolant Thermostat Replacement (2H0, LDE, LFH), Engine Coolant Thermostat Replacement (LUV, LUJ)

SYMPTOMS - ENGINE COOLING

Important Preliminary Inspections Before Starting

Before using the Symptom diagnosis, perform the following:

• Perform Diagnostic System Check - Vehicle and verify all of the following items:

• Engine control module (ECM) and malfunction indicator lamp (MIL) are operating correctly.
• There are no diagnostic trouble codes (DTCs) stored.
• Scan tool data is within a normal operating range.

• Verify the customer concern.
• Perform the Visual/Physical Inspection in this section. The visual/physical inspection is extremely important, and can lead to correcting a condition without additional testing. It may also help reveal the cause of an intermittent condition.
• Locate the correct symptom. Perform the tests and inspections associated with the symptom.

Review the entire cooling system operation in order to familiarize yourself with the system functions. Refer to Cooling Fan Description and Operation (LUJ or LUV), Cooling Fan Description and Operation (2H0), and Cooling System Description and Operation.

Visual/Physical Inspection

CAUTION: Use the connector test adapter kit EL-35616-F for any test that requires probing the following items:

• The control module harness connectors
• The electrical center fuse/relay cavities
• The component terminals
• The component harness connector

Using this kit will prevent damage caused by the improper probing of connector terminals.

Several of the symptom procedures call for a careful visual and physical inspection. This can lead to correcting a condition without further tests and can save time. This inspection should include the following:

• Ensure that the control module grounds are clean, tight, and correctly located.
• Inspect cooling system hoses and pipes for splits, kinks, and improper connections. Inspect thoroughly for any type of leak or restriction.
• Inspect for a dirty or restricted radiator or HVAC condenser.
• Inspect for aftermarket devices which could affect the operation of the cooling system.
• Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
• Inspect the coolant recovery reservoir for proper coolant level.

Identifying Intermittent Conditions

Many intermittent conditions occur with harness or connector movement due to engine torque, rough pavement, vibration or physical movement of a component. Refer to the following for a list to help isolate an intermittent condition:

• Water intrusion in connectors, terminals, or components
• Poor connector mating
• Terminal contact
• High circuit or component resistance-High resistance can include any resistance, regardless of the amount, which can interrupt the operation of the component.
• Harness' that are routed too tight, or chaffed circuits
• High or low ambient temperatures
• High or low engine coolant temperatures
• High underhood temperatures
• Heat build up in components or circuits due to circuit resistance, poor terminal contact, or high electrical load
• High or low system voltage
• High vehicle load conditions
• Rough road surface
• Electro-magnetic interference (EMI)/circuit interference from relays, solenoids or other electrical surge
• Incorrect installation of non-factory, aftermarket, or after factory add on accessories

If an intermittent fault is detected, refer to Testing for Intermittent Conditions and Poor Connections for specific strategies in diagnosing intermittent conditions.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

• Cooling Fan Always On (LUJ or LUV), Cooling Fan Always On (2H0)
• Cooling Fan Inoperative (LUJ or LUV), Cooling Fan Inoperative (2H0)
• Engine Overheating
• Loss of Coolant
• Thermostat Diagnosis
• Engine Fails To Reach Normal Operating Temperature

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