Engine Cooling System Chevrolet Aveo I рестайлинг

Fastener Tightening Specifications

Scheme 1

Scheme 2

Scheme 3

DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Diagnostic Starting Point - Engine Cooling

Begin diagnosis with the Diagnostic System Check - Vehicle . The Diagnostic System Check will provide the following information

1. The identification of the control modules which command the system
2. The ability of the control modules to communicate through the serial data circuit
3. The identification of any stored diagnostic trouble codes (DTCs) and their status

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

Typical Scan Tool Data

RCT Sensor

Circuit/System Description

The radiator coolant temperature (RCT) sensor is a variable resistor that measures the temperature of the engine coolant in the radiator. The engine control module (ECM) supplies 5 volts to the RCT signal circuit and supplies a ground to the low reference circuit.

The following table illustrates the difference between temperature, resistance, and voltage

Conditions for Running the DTC

P00B3

1. DTCs P0112 or P0113 are not set.
2. The engine run time is greater than 10 seconds.
3. The intake air temperature (IAT) is less than 70°C (158°F).
4. The DTC runs continuously when either of the above conditions are met.

P00B4

1. DTCs P0112 or P0113 are not set.
2. The engine run time is greater than 60 seconds.
3. The intake air temperature (IAT) is warmer than -7°C (19°F).
4. The DTC runs continuously when either of the above conditions are met.

P00B3

The ECM detects that the RCT sensor is greater than 149°C (300°F).

P0118

The ECM detects that the RCT sensor is colder than -59°C (-74°F).

Action Taken When the DTC Sets

1. DTC P00B3 and P00B4 are Type B DTCs.
2. The cooling fans will be commanded ON by the ECM.

Conditions for Clearing the MIL/DTC

DTC P00B3 and P00B4 are Type B DTCs.

Diagnostic Aids

1. After starting the engine, the RCT sensor temperature should rise steadily, then stabilize after the thermostat opens.
2. Test the RCT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor.
3. If the vehicle has set overnight, the RCT sensor and the ECT sensor values should display within 3°C (5°F).

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-inline-harness-connector-end-views-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-service-repair-connector-and-terminal-repairs__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-testing-diagnosis-2-of-2__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-fuses-circuit-breakers-and-wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Engine idling, observe the DTC information with a scan tool. DTCs P00B3 or P00B4 should not set.
2. 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.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the RCT sensor.
2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal B and ground. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
3. Ignition ON, verify the scan tool RCT sensor parameter is at -40°C (-40°F). If greater than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
4. Ignition ON, clear the DTC information with a scan tool.
5. Install a 1A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the RCT sensor parameter is greater than 128°C (262°F). If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
6. If all circuits test normal, test or replace the RCT sensor.

Component Testing

1. Ignition OFF, disconnect the harness connector at the RCT sensor.
2. Test the RCT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the table and verify that the resistance is within 5 percent of the specification. If not within the specified range, replace the RCT sensor.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

RCT Sensor

Circuit Description

The radiator coolant temperature (RCT) sensor is a variable resistor that measures the temperature of the engine coolant in the radiator. The engine control module (ECM) supplies 5 volts to the RCT signal circuit and supplies a ground to the low reference circuit.

The following table illustrates the difference between temperature, resistance, and voltage

1. DTCs P00B3, P00B4, P0112, P0113, P0117, P0118, P0502, or P0503 are not set.
2. The ignition has been off for greater than 8 hours before vehicle is started.
3. The ignition is ON, or the engine is running.
4. The intake air temperature (IAT) is greater than -7°C (19°F).
5. The fuel level is greater than 10 percent.
6. The engine block heater (if equipped) is not detected.
7. The DTC runs once per ignition cycle when the above conditions are met.

Conditions for Setting the DTC

The ECM detects the RCT sensor is 20°C (68°F) warmer than the ECT sensor at engine start-up for 5 seconds.

DTC P00B6 is a Type B DTC.

DTC P00B6 is a Type B DTC.

1. If the vehicle has set overnight, the RCT sensor and the ECT sensor values should display within 3°C (5°F).
2. After starting the engine, the RCT sensor temperature should rise steadily, then stabilize after the thermostat opens.
3. Test the RCT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor.
4. Inspect for the correct operation of the engine cooling system and verify the correct coolant level.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-inline-harness-connector-end-views-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-service-repair-connector-and-terminal-repairs__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-testing-diagnosis-2-of-2__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-fuses-circuit-breakers-and-wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Engine running, observe the DTC information with a scan tool. Verify that DTC P0112, P0113, P0117, P0118, or P0128 is not set. If any of the DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-trouble-code-dtc-list) .
2. 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.

1. Ignition OFF, disconnect the harness connector at the RCT sensor.
2. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal B and ground. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
3. Ignition ON, verify the scan tool RCT sensor parameter is at -40°C (-40°F). If greater than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
4. Ignition ON, clear the DTC information with a scan tool.
5. Install a 1A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool RCT sensor parameter is greater than 128°C (262°F). If less than specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
6. If all circuits test normal, test or replace the RCT sensor.

1. Ignition OFF, disconnect the harness connector at the RCT sensor.
2. Test the RCT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the table and verify that the resistance is within 5 percent of the specification. If not within the specified range, replace the RCT sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) monitors the temperature of the engine radiator coolant. The thermostat is controlled by the ECM. The ECM controls the thermostat with a pulse width modulated (PWM) signal. The ECM compares the radiator coolant temperature to the engine coolant temperature in order to regulate coolant flow through the radiator.

1. DTCs P00B3, P00B4, P00B6, P0116, P0117, and P0118 are not set.
2. The engine run time is greater than 300 seconds. OR
3. The engine coolant temperature is greater than 106°C (223°F).
4. The DTC runs continuously when the above conditions are met.

The ECM detects the difference between the RCT sensor and the ECT sensor is greater than 30°C (68°F) when the ECT sensor is warmer than 117°C (242°F).

DTC P00B7 is a Type B DTC.

DTC P00B7 is a Type B DTC.

If the customer's concern is that the engine does not reach operating temperature or that the heater output is low, refer to Thermostat Diagnosis .

Schematic Reference

Engine Cooling Schematics

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-inline-harness-connector-end-views-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-service-repair-connector-and-terminal-repairs__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-testing-diagnosis-2-of-2__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-fuses-circuit-breakers-and-wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Perform the «Loss of Coolant»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant) to verify correct fluid level.
2. Perform the «Thermostat Diagnosis»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__thermostat-diagnosis) to verify correct normal operating temperature.
3. Engine idling, observe the DTC information with a scan tool. Verify that DTCs P0116, P0117, P0118, P00B3, P00B4, P00B6, P0597, P0598, or P0599 are not set. If any of the listed DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-trouble-code-dtc-list) for further diagnosis.
4. 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.

1. Ignition ON, clear the DTC information with a scan tool.
2. Ignition OFF, disconnect the harness connector at the RCT sensor.
3. Test for less than 5 ohms between the low reference circuit terminal B and ground. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
4. Ignition ON, verify the scan tool RCT sensor parameter is at -40°C (-40°F). If greater than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
5. Ignition ON, clear the DTC information with a scan tool.
6. Install a 1A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool RCT sensor parameter is greater than 128°C (262°F). If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
7. If all circuits test normal, test or replace the RCT sensor.

1. Ignition OFF, disconnect the harness connector at the RCT sensor.
2. Test the RCT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the table and verify that the resistance is within 5 percent of the specification. If not within the specified range, replace the RCT sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming

Diagnostic Instructions (w/single fan)

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information (w/single fan)

Circuit/System Description (w/single fan)

The engine control module (ECM) commands the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, the fan is turned ON at a reduced speed. High speed the fan is turned ON at full speed.

In low speed operation, the ECM applies ground to the coil side of the low speed fan relay. This energizes the coil and applies voltage directly to the cooling fan through the switch side of the low relay. The fan is connected in series to the cooling fan resistor causing the fan to operate at low speed.

In high speed operation, the ECM applies a ground to the coil side of the fan high or fan control relay. When energized, the fan high or control relay applies voltage directly to the cooling fan through the switch side of the relay. Because the low speed fan relay is de-energized the cooling fan receives full voltage and operates at high speed.

Conditions for Running the DTC (w/single fan)

1. The ignition is ON, or the engine is running.
2. The DTCs run continuously once the above conditions are met.

P0480

The ECM detects an open or a short on the low speed cooling fan relay control circuit for more than 1 second.

P0481

The ECM detects an open or a short on the high speed cooling fan relay control circuit for more than 1 second.

Action Taken When the DTC Sets (w/single fan)

DTC P0480 and P0481 are Type B DTCs.

Conditions for Clearing the MIL/DTC (w/single fan)

DTC P0480 and P0481 are Type B DTCs.

Reference Information (w/single fan)

Schematic Reference

Engine Cooling Schematics

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-inline-harness-connector-end-views-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-service-repair-connector-and-terminal-repairs__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-testing-diagnosis-2-of-2__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-fuses-circuit-breakers-and-wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification (w/single fan)

1. Ignition ON, command the appropriate fan relay ON and OFF with a scan tool. Listen or feel the relay click.
2. 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.

Circuit/System Testing (w/single fan)

1. Ignition OFF, disconnect the cooling fan relays.
2. Ignition ON, verify that a test lamp illuminates between ground and the relay coil ignition circuit terminal 85. If the test lamp does not illuminate, test the relay coil ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay coil ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.
3. Test for less than 0.1 volt between ground and the relay coil control circuit terminal 86. If greater than the specified range, test the relay coil control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Connect a test lamp between the relay coil control circuit terminal 86 and the relay coil ignition circuit terminal 85.
5. Command the fan relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the relay coil control circuit for a short to ground. If the circuit tests normal, replace the ECM. If the test lamp is always OFF, test the relay coil control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
6. If all circuits test normal, test or replace the relay.

Component Testing (w/single fan)

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 70-110 ohms between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified range, replace the relay.
4. Install a 20A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the relay.

Repair Procedures (w/single fan)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(/chevrolet/aveo/i-2006-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
2. «Control Module References»(/chevrolet/aveo/i-2006-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

Diagnostic Instructions (w/dual fan)

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information (w/dual fan)

Circuit/System Description (w/dual fan)

The engine control module (ECM) commands the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.

In low speed operation, the ECM applies ground to the coil side of the low speed fan relay. This energizes the coil and applies voltage directly to the main cooling fan through the switch side of the low relay. The main fan is connected in series to the auxiliary cooling fan through the de-energized series/parallel fan control relay. The series circuit operates both fans at low speed.

In high speed operation, the ECM applies a ground to the coil side of the low speed fan relay, the fan control relay, and the high speed fan relay. When energized, the high speed fan relay applies voltage directly to the auxiliary cooling fan through the switch side of the relay. Simultaneously, the low speed fan relay and the fan control relay provide ignition voltage and a direct path to ground for the main cooling fan. With both fans connected in a parallel circuit, each fan receives full voltage and operates at high speed.

Conditions for Running the DTC (w/dual fan)

1. The ignition is ON, or the engine is running.
2. The DTCs run continuously once the above conditions are met.

The ECM detects an open or a short on the low speed cooling fan relay control circuit for more than 1 second.

The ECM detects an open or a short on the high speed cooling fan relay control circuit for more than 1 second.

Action Taken When the DTC Sets (w/dual fan)

DTC P0480 and P0481 are Type B DTCs.

Conditions for Clearing the MIL/DTC (w/dual fan)

DTC P0480 and P0481 are Type B DTCs.

Reference Information (w/dual fan)

Schematic Reference

Engine Cooling Schematics

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-inline-harness-connector-end-views-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-service-repair-connector-and-terminal-repairs__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-testing-diagnosis-2-of-2__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-fuses-circuit-breakers-and-wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification (w/dual fan)

1. Ignition ON, command the appropriate fan relay ON and OFF with a scan tool. Listen or feel the relay click.
2. 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.

Circuit/System Testing (w/dual fan)

1. Ignition OFF, disconnect all three cooling fan relays.
2. Ignition ON, verify that a test lamp illuminates between ground and the relay coil ignition circuit terminal 85. If the test lamp does not illuminate, test the relay coil ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay coil ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.
3. Test for less than 0.1 volt between ground and the relay coil control circuit terminal 86. If greater than the specified range, test the relay coil control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Connect a test lamp between the relay coil control circuit terminal 86 and the relay coil ignition circuit terminal 85.
5. Command the fan relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the relay coil control circuit for a short to ground. If the circuit tests normal, replace the ECM. If the test lamp is always OFF, test the relay coil control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
6. If all circuits test normal, test or replace the relay.

Component Testing (w/dual fan)

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 70-110 ohms between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified range, replace the relay. If greater than the specified range, replace the relay.
4. Install a 20A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the relay.

Repair Procedures (w/dual fan)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(/chevrolet/aveo/i-2006-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
2. «Control Module References»(/chevrolet/aveo/i-2006-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) controls the pulse width modulated (PWM) thermostat. The thermostat controls coolant flow and regulates the engine operating temperature. Ignition voltage is supplied directly to the thermostat. The ECM controls the thermostat by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

Conditions for Running the DTCs

1. The ignition is ON, or the engine is running.
2. The DTCs run continuously once the above condition is met

The ECM detects the engine coolant thermostat heater control circuit is open, shorted to ground, or shorted to a voltage.

DTCs P0597, P0598, and P0599 are Type B DTCs.

Conditions for Clearing the DTC

DTCs P0597, P0598, and P0599 are Type B DTCs.

Schematic Reference

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-inline-harness-connector-end-views-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-service-repair-connector-and-terminal-repairs__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-testing-diagnosis-2-of-2__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-fuses-circuit-breakers-and-wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the DTC information with a scan tool. DTC P0689 and P1682 should not be set. If a DTC is set, refer to «DTC P0685, P0689, or P0690»(ref-318492-S29331511532009061700000) .
2. Ignition ON, observe the following scan tool control circuit status parameters. Each parameter should display OK or Not Run. Eng Clnt Therm Htr Ckt Short Gnd Test Status Eng Clnt Therm Htr Ckt Open Test Status Eng Clnt Therm Htr Ckt Short Volts Test Status
3. 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.

1. Ignition OFF, disconnect the harness connector at the engine coolant thermostat heater.
2. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 2 and ground. If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test all the components connected to the ignition circuit and replace as necessary.
3. Connect a DMM, set on the diode setting, between the control circuit terminal 1 and ground. The DMM reading should not display OL. If not the specified range, test the control circuit for a short to voltage or open/high resistance. If the circuits test normal, replace the ECM.
4. Command the engine coolant thermostat heater to 10 percent with a scan tool. The DMM reading should be greater than 2.5 volts. If less than the specified value, test the control circuit for a short to ground. If the circuits test normal, replace the ECM.
5. If all circuits test normal, test or replace the engine coolant thermostat heater.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Engine Coolant Thermostat Replacement (1.4L LDT/1.6 LXV)»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Control Module References»(/chevrolet/aveo/i-2006-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

Symptoms - Engine Cooling

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) before using the Symptom Tables in order to verify that all of the following are true: There are no DTCs set. The control module(s) can communicate via the serial data link.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to «Cooling System Description and Operation»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-description-and-operation) .

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the system.
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions.

Symptom List

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

1. «Cooling Fan Always On»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Cooling Fan Inoperative (w/single fan)»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling Fan Inoperative (w/dual fans)»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system)
3. «Engine Overheating»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__engine-overheating)
4. «Loss of Coolant»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant)
5. «Thermostat Diagnosis»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__thermostat-diagnosis)
6. «Coolant Heater Inoperative»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__coolant-heater-inoperative)
7. «Engine Fails To Reach Normal Operating Temperature»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__engine-fails-to-reach-normal-operating)

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) controls cooling fan operation in either high speed or low speed mode, depending on cooling requirements. To activate a fan, the ECM applies ground to the coil side of the applicable fan relay. This energizes the coil and applies voltage directly to the cooling fan through the switch side of the relay.

Schematic Reference

Engine Cooling Schematics

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-inline-harness-connector-end-views-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-service-repair-connector-and-terminal-repairs__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-testing-diagnosis-2-of-2__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-fuses-circuit-breakers-and-wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Verify that DTCs P0480 and P0481 are not set. If any DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-trouble-code-dtc-list) .
2. Ignition ON, verify with a scan tool that the ECM is not commanding the fan ON. If the fan is commanded ON, refer to «DTC P0480 or P0481 (w/single fan)»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «DTC P0480 or P0481 (w/dual fan)»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Ignition ON, observe that the fan is not ON.

1. Ignition OFF, disconnect each cooling fan relay one at a time.
2. Ignition ON, observe that the cooling fans are not ON. If the fans are ON, test for a short to voltage in the relay controlled output circuit terminal 87. If the fans are not ON, test for a short to ground in the relay coil control circuit terminal 86.
3. If all circuits test normal, test or replace the cooling fan relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Relay Replacement (Within an Electrical Center)

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) commands the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, the fan is turned ON at a reduced speed. High speed the fan is turned ON at full speed.

In low speed operation, the ECM applies ground to the coil side of the low speed fan relay. This energizes the coil and applies voltage directly to the cooling fan through the switch side of the low relay. The fan is connected in series to the cooling fan resistor causing the fan to operate at low speed.

In high speed operation, the ECM applies a ground to the coil side of the fan high or fan control relay. When energized, the fan high or control relay applies voltage directly to the cooling fan through the switch side of the relay. Because the low speed fan relay is de-energized the cooling fan receives full voltage and operates at high speed.

Schematic Reference

Engine Cooling Schematics

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-inline-harness-connector-end-views-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-service-repair-connector-and-terminal-repairs__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-testing-diagnosis-2-of-2__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-fuses-circuit-breakers-and-wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Verify that DTCs P0480 and P0481 are not set. If any DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-trouble-code-dtc-list) .
2. Ignition ON, command the fan relays ON and OFF with a scan tool. You should hear or feel each relay click. If any fan relay does not click, refer to «DTC P0480 or P0481 (w/single fan)»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «DTC P0480 or P0481 (w/dual fan)»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Ignition ON, command the appropriate fan relay ON and OFF with a scan tool. Verify that the fan turns ON and OFF when changing between the commanded states.

1. Ignition OFF, disconnect the cooling fan relays.
2. Ignition ON, verify that a test lamp illuminates between the relay switch B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the relay switch B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay switch B+ circuit fuse is open, test the relay controlled output circuit for a short to ground. If the circuit tests normal, test or replace the relay.
3. Connect a 20A fused jumper between the relay switch B+ circuit terminal 30 and the relay controlled output circuit terminal 87 of the fan low relay. Verify the fan is ON at low speed If the fan is ON at high speed, test the cooling fan resistor for a short circuit. If the fan is not ON, test the relay controlled output circuit for a short to ground or an open/high resistance. If the circuit tests normal, test the fan ground circuit for an open/high resistance. If the circuit tests normal, replace the fan.
4. Connect a 30A fused jumper between the relay switch B+ circuit terminal 30 and the relay controlled output circuit terminal 87 of the fan high or fan control relay. Verify the fan is ON. If the fan is not ON, test the relay controlled output circuit for a short to ground or an open/high resistance.
5. If all circuits test normal, test or replace the relay.

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 70-110 ohms of resistance between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified range, replace the relay.
4. Install a 20A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms of resistance between terminals 30 and 87. If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(/chevrolet/aveo/i-2006-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
2. «Engine Coolant Fan Replacement»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system)

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) commands the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.

In low speed operation, the ECM applies ground to the coil side of the low speed fan relay. This energizes the coil and applies voltage directly to the main cooling fan through the switch side of the low relay. The main fan is connected in series to the auxiliary cooling fan through the de-energized series/parallel fan control relay. The series circuit operates both fans at low speed.

In high speed operation, the ECM applies a ground to the coil side of the low speed fan relay, the fan control relay, and the high speed fan relay. When energized, the high speed fan relay applies voltage directly to the auxiliary cooling fan through the switch side of the relay. Simultaneously, the low speed fan relay and the fan control relay provide ignition voltage and a direct path to ground for the main cooling fan. With both fans connected in a parallel circuit, each fan receives full voltage and operates at high speed.

Schematic Reference

Engine Cooling Schematics

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-inline-harness-connector-end-views-diagnosis__circuit-testing)
2. «Connector Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-service-repair-connector-and-terminal-repairs__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-testing-diagnosis-2-of-2__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/chevrolet/aveo/i-2006-2012/remont/body-electrical/#wiring-systems-and-power-management-fuses-circuit-breakers-and-wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Verify that DTCs P0480 and P0481 are not set. If any DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/chevrolet/aveo/i-2006-2012/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-trouble-code-dtc-list) .
2. Ignition ON, command the fan relays ON and OFF with a scan tool. You should hear or feel each relay click. If any fan relay does not click, refer to «DTC P0480 or P0481 (w/single fan)»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system) or «DTC P0480 or P0481 (w/dual fan)»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Ignition ON, command the appropriate fan relay ON and OFF with a scan tool. Verify that the fans turn ON and OFF when changing between the commanded states.

1. Ignition OFF, disconnect the cooling fan relays.
2. Connect a 30A fused jumper between the relay switch circuit terminal 30 and the ground circuit terminal 87 at the series/parallel fan control relay connector. This will complete the main fan ground circuit. Leave this jumper in place for the remainder of this procedure.
3. Ignition ON, verify that a test lamp illuminates between the relay switch B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the appropriate relay switch B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay switch B+ circuit fuse is open, test the relay controlled output circuit for a short to ground. If the circuit tests normal, test or replace the relay.
4. Connect a 30A fused jumper between the relay switch B+ circuit terminal 30 and the relay controlled output circuit terminal 87. Verify the appropriate fan is ON. If the appropriate fan is not ON, test the relay controlled output circuit for a short to ground or an open/high resistance. If the circuit tests normal, test the fan ground circuit for an open/high resistance. If the circuit tests normal, replace the fan.
5. Install the fan control relay. Verify both fans are ON at low speed. If both fans are not ON, test the relay controlled output circuit terminal 87A of the fan control relay for a short to ground or an open/high resistance.
6. If all circuits test normal, test or replace the relay.

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 70-110 ohms of resistance between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified range, replace the relay.
4. Test for less than 2 ohms of resistance between terminals 30 and 87A. If greater than the specified range, replace the relay.
5. Install a 20A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms of resistance between terminals 30 and 87. If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(/chevrolet/aveo/i-2006-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
2. «Engine Coolant Fan Replacement»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system)

Engine Overheating

Loss of Coolant

Thermostat Diagnosis

Coolant Heater Inoperative

Engine Fails To Reach Normal Operating Temperature

Tools Required

J-36649 Cooling System Pressure Test Adapter. See Special Tools .

The surge tank cap maintains proper pressure, protects the system from high pressure by opening a pressure valve, and protects the coolant hoses from collapsing because of a vacuum.

1. Wash any sludge from the surge tank cap and the valve seat of the vacuum pressure valve for the surge tank cap.
2. Check for any damage or deformity to the vacuum pressure valve for the surge tank cap. If any damage or deformity is found, replace the cap.
3. Install a suitable cooling system pressure tester to the cap using the J-36649 . See «Special Tools»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__special-tools) .
4. Pull the vacuum pressure valve open. If the surge tank cap does not seal properly, replace the surge tank cap.
5. Pressurize the cap to 120-160 kPa (17-23 psi).
6. Wait 10 seconds and check the pressure held by the tank cap tester.
7. If the pressure held by the cooling system pressure tester falls below 80 kPa (16 psi), replace the surge tank cap.

Cooling System Draining and Filling

1. Place a pan below the vehicle to catch the draining coolant.
2. Remove the surge tank cap.
3. Unplug the drain cock.
4. Catch the escaping fluid in a drain pan.
5. Remove all sludge and dirt from inside the surge tank. Refer to «Radiator Surge Tank Replacement (1.4L/1.5L/1.6L)»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Plug the drain cock.
7. Add clean water to the surge tank.
8. Fill the tank slowly so that the upper reservoir hose remains above the water line. This allows the air inside the cooling system to escape.
9. Start the engine.
10. Run the engine until the thermostat opens. You can tell the thermostat is open when both radiator hoses are hot to the touch.
11. Stop the engine.
12. Repeat steps 1-9 until the drained water is clear and free of coolant and rust.
13. Fill the cooling system through the surge tank with a mixture of ethylene glycol antifreeze and water. The mixture must be at least 50 percent antifreeze, but not more than 60 percent antifreeze for cold weather operation.
14. Fill the surge tank to the specified MAX fill mark on the outside of the tank.

Removal Procedure

1. Drain the engine cooling system to a level below the thermostat housing. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
2. Remove the timing belt rear hood. Refer to TIMING BELT COVER REPLACEMENT.
3. Remove the coolant pump mounting bolts.
4. Remove the coolant pump from the cylinder block.
5. Remove the ring seal from the coolant pump.

Coolant Pump Cleaning and Inspection

1. Inspect the coolant pump body for cracks and leaks.
2. Inspect the coolant pump bearing for play or abnormal noise.
3. Inspect the coolant pump pulley for excessive wear. If the coolant pump is defective, replace the coolant pump as a unit.
4. Clean the mating surfaces of the coolant pump and cylinder block.

Installation Procedure

1. Install a new ring seal to the coolant pump.
2. Coat the sealing surface of the ring seal with Lubriplate®.
3. Install the coolant pump to the engine block.
4. Secure the coolant pump to the engine block with the mounting bolts. Tighten: Tighten the coolant pump mounting bolts to 10 N.m (89 lb in).
5. Install the rear timing belt rear hood. Refer to TIMING BELT COVER REPLACEMENT.
6. Refill the engine cooling system. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .

1. Drain the coolant. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
2. Remove the accessory belt. Refer to Drive Belt Replacement.
3. Remove the generator. Refer to Generator Replacement (1.2L ).
4. Remove the water pump retaining nuts, bolts (1).
5. Remove the water pump (2).
6. Remove the ring seal from the water pump.
7. Inspect the water pump for cracks, leaks or abnormal noises.
8. Cleaning the mating surfaces of the water pump and the cylinder head.

1. Install the new ring seal to the water pump.
2. Install the water pump (2) to the engine block. Tighten: Tighten the water pump retaining bolts (1) and nuts to 10 N.m (89 lb in).
3. Install the generator. Refer to Generator Replacement (1.2L ).
4. Install the accessory belt. Refer to Drive Belt Replacement.
5. Refill the engine cooling system. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .

Coolant Pump Replacement (1.4L LDT/1.6 LXV)

Special Tools

1. EN-48356 Engine Fixture
2. EN-49201 Water Pump Pulley Remover/Installer

1. Drain the coolant. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
2. Remove the air cleaner assembly. Refer to «AIR CLEANER ASSEMBLY REPLACEMENT»(ref-318492-S06742919042009061700000) .
3. Remove the RH head lamp assembly. Refer to «Headlamp Replacement (Notchback)»(/chevrolet/aveo/i-2006-2012/remont/exterior-lights/#lighting-systems) or «Headlamp Replacement (Hatchback)»(/chevrolet/aveo/i-2006-2012/remont/exterior-lights/#lighting-systems) .
4. Disconnect the A/C pipe retainer and move the A/C pipe.
5. Remove the water pump pulley retaining bolts using EN-48356: fixture.
6. Remove the accessory belt. Refer to «DRIVE BELT REPLACEMENT»(ref-318523-S01147363072009061700000) .
7. Fix the engine using EN-48356: fixture.
8. Remove the engine mount.
9. Remove the water pump pulley.
10. Remove the water pump retaining bolts (1).
11. Remove the water pump (2).
12. Remove the ring seal from the water pump.
13. Inspect the water pump for cracks, leaks or abnormal noise.
14. Cleaning the mating surfaces of the water pump and the cylinder head.

1. Install a new ring seal to the water pump.
2. Install the water pump (2) to the engine front cover. Tighten: Tighten the water pump retaining bolts (1) to 10 N.m (89 lb in).
3. Install the water pump pulley.
4. Install the engine mount.
5. Install the accessory belt. Refer to «DRIVE BELT REPLACEMENT»(ref-318523-S01147363072009061700000) .
6. Connect the A/C pipe retainer and fix the A/C pipe.
7. Install the RH head lamp assembly. Refer to «Headlamp Replacement (Notchback)»(/chevrolet/aveo/i-2006-2012/remont/exterior-lights/#lighting-systems) or «Headlamp Replacement (Hatchback)»(/chevrolet/aveo/i-2006-2012/remont/exterior-lights/#lighting-systems) .
8. Install the air cleaner assembly. Refer to «AIR CLEANER ASSEMBLY REPLACEMENT»(ref-318492-S06742919042009061700000)
9. Refill the engine cooling system. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .

1. Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection
2. Drain the coolant. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
3. Remove the rear timing belt cover. Refer to Timing Belt Cover Replacement for the 1.4L DOHC engine, or Timing Belt Cover Replacement for the 1.6L (L91) engine.
4. Remove the coolant pump mounting bolts.
5. Remove the coolant pump.
6. Remove the seal ring from the coolant pump.

1. Install a new seal ring to the coolant pump.
2. Coat the sealing surface of the seal ring with Lubriplater®.
3. Install the coolant pump to the engine block with the flange aligned with the recess of the rear timing belt cover. CAUTION: Refer to Fastener Caution.
4. Install the coolant pump mounting bolts and tighten to 10 N.m (89 lb in).
5. Install the rear timing belt cover. Refer to Timing Belt Cover Replacement for the 1.4 DOHC engine, or Timing Belt Cover Replacement for the 1.6L (L91) engine.
6. Fill the engine cooling system. Refer to Cooling System Draining and Filling.
7. Connect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection

1. Drain the engine coolant to below the level of the surge tank.
2. Loosen the overflow hose clamps and disconnect the overflow hose from the top of the surge tank.
3. Disconnect the coolant temperature sensor connector.
4. Remove the EGR valve and pipe.
5. Remove the tank attaching nuts.
6. Remove the tank from the vehicle.
7. Clean the inside and the outside of the surge tank and the surge tank cap with soap and water.
8. Rinse the surge tank and the cap thoroughly.

1. Install the surge tank to the vehicle.
2. Secure the surge tank with the attaching nuts. Tighten: Tighten the surge tank attaching nuts to 20 N.m (178 lb in).
3. Install the EGR valve and pipe.
4. Connect the coolant temperature sensor connector.
5. Connect the overflow hose to the surge tank.
6. Secure the overflow hose to the surge tank with the hose clamps.
7. Fill the surge tank with the coolant to the center ridge or to the MAX mark.

1. Drain the engine coolant to below the level of the surge tank.
2. Loosen the overflow hose clamps and disconnect the overflow hose from the top of the surge tank.
3. Remove the tank attaching nuts.
4. Remove the tank from the vehicle.
5. Clean the inside and the outside of the surge tank and the surge tank cap with soap and water.
6. Rinse the surge tank and the cap thoroughly.

1. Install the surge tank to the vehicle.
2. Secure the surge tank with the attaching nuts and tighten to 10 N.m (89 lb in).
3. Connect the overflow hose to the surge tank.
4. Secure the overflow hose to the surge tank with the hose clamps.
5. Fill the surge tank with the coolant to the center ridge, or to the MAX mark.

Scheme 4

1. Drain the engine coolant. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
2. Drain the engine oil. Refer to «Engine Oil and Oil Filter Replacement»(ref-318523-S38469995562009061700000) .
3. Remove the exhaust manifold.
4. Remove the coolant pipe bolts from the engine coolant distributor case (1).
5. Remove the coolant pipe bolts from the engine front cover (2).
6. Remove the oil cooler tightening bolts (3). Remove the heat exchanger with the gasket.

1. Install the heat exchanger with the gasket to the oil cooler housing. Tighten: Tighten the heat exchanger bolts to 8 N.m(70.8 lb in).
2. Insert the coolant pipes to the oil cooler housing with the gasket.
3. Install the oil cooler tightening bolts (3). Tighten: Tighten the oil cooler tightening bolts to 25 N.m (18.4 lb ft).
4. Install the coolant pipe bolts to the engine front cover (2). Tighten: Tighten the coolant pipe bolts to 8 N.m (70.8 lb in).
5. Install the coolant pipe bolts to the engine coolant distributor case (1). Tighten: Tighten the coolant pipe bolts to 8 N.m (70.8 lb in).
6. Remove the exhaust manifold.

1. Disconnect the negative battery cable.
2. Disconnect the cooling fan electrical connector(s).
3. Remove the electric cooling fan mounting bolts.
4. Remove the electric cooling fan.

1. Install the electric cooling fan.
2. Install the electric cooling fan mounting bolts and tighten to 4 N.m (35 lb in).
3. Connect the cooling fan electrical connector.

1. Drain the coolant. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
2. Remove the timing belt rear hood. Refer to TIMING BELT COVER REPLACEMENT.
3. Loosen the hose clamp on the upper radiator hose at the thermostat housing.
4. Disconnect the upper radiator hose from the thermostat housing.
5. Remove the mounting bolts that hold the thermostat housing to the cylinder head.
6. Remove the thermostat housing from the cylinder head.
7. Remove the thermostat from its recess in the cylinder head.
8. Inspect the valve seat for foreign matter that could prevent the valve from sealing properly.
9. Clean the thermostat housing and the cylinder head mating surfaces.

1. Install the thermostat into the cylinder head recess.
2. Install the thermostat housing.
3. Secure the thermostat housing to the cylinder head with the mounting bolts. Tighten: Tighten the thermostat housing mounting bolts to 20 N.m (15 lb ft).
4. Install the timing belt rear hood. Refer to TIMING BELT COVER REPLACEMENT.
5. Connect the upper radiator hose to the thermostat housing.
6. Secure the upper radiator hose to the thermostat housing with a hose clamp.
7. Refill the engine cooling system. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .

1. Drain the coolant. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
2. Remove the thermostat housing retaining bolts.
3. Remove the thermostat housing.
4. Remove the thermostat.
5. Inspect the thermostat for proper operation. Refer to «Thermostat Diagnosis»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__thermostat-diagnosis) .
6. Clean the thermostat housing and the cylinder head mating surfaces.

1. Install the thermostat into the cylinder head recess.
2. Install the thermostat housing. Tighten: Tighten the thermostat housing retaining bolts to 10 N.m (89 lb in).
3. Refill the engine cooling system. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .

1. Disconnect the battery negative cable. Refer to «Battery Negative Cable Disconnection and Connection»(/chevrolet/aveo/i-2006-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
2. Drain the coolant. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
3. Remove the upper radiator hose from the thermostat housing.
4. Disconnect the thermostat wiring harness plug.
5. Remove the thermostat housing retaining bolts.
6. Remove the thermostat housing.
7. Inspect the thermostat for proper operation. Refer to «Thermostat Diagnosis»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__thermostat-diagnosis) .
8. Clean the thermostat housing and the cylinder head mating surfaces.

1. Fit the thermostat housing to the coolant distributor and use the NEW gasket.
2. Install the thermostat housing. Tighten: Tighten the thermostat housing retaining bolt to 8 N.m (5.9 lb ft).
3. Connect the thermostat wiring harness plug.
4. Install the upper radiator hose from the thermostat housing.
5. Refill the engine cooling system. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
6. Connect the battery negative cable. Refer to «Battery Negative Cable Disconnection and Connection»(/chevrolet/aveo/i-2006-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

1. Drain the coolant. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
2. Disconnect the upper radiator hose from the thermostat housing.
3. Disconnect the throttle body coolant inlet hose from the thermostat housing.
4. Remove the thermostat bolts.
5. Remove the thermostat housing.
6. Remove the thermostat with the gasket.
7. Inspect the gasket for cracks or other damage.
8. Inspect the valve seat for foreign matter that could prevent the valve from seating properly.
9. Clean the thermostat housing and mating surface.

1. Install the thermostat with the bolts and the thermostat housing and tighten to 20 N.m (15 lb ft).
2. Secure the upper radiator hose to the thermostat housing with a hose clamp.
3. Connect the throttle body coolant inlet hose to the thermostat housing.
4. Refill the engine cooling system. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .

1. Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection.
2. Remove the power steering oil tank. Refer to POWER STEERING FLUID RESERVOIR REPLACEMENT.
3. Drain the coolant. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
4. Remove the electric cooling fans. Refer to «Engine Coolant Fan Replacement»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Disconnect the upper cooling fan hose from the radiator.
6. Disconnect the lower radiator hose from the radiator.
7. Remove the return hose from the surge tank at the radiator.
8. Remove the left upper radiator retaining bracket.
9. Remove the right upper radiator retaining bracket.
10. Remove the A/C gas. Refer to REFRIGERANT RECOVERY AND RECHARGING
11. Remove the high pressure pipe bolt from both sides of the A/C condenser. Refer to HEATING, VENTILATION, AND AIR CONDITIONING.
12. Remove up the radiator from the vehicle with the A/C condenser.
13. Remove the A/C condenser from the radiator.

1. Install the A/C condenser to the radiator.
2. Install the radiator with the A/C condenser.
3. Install the high pressure pipe bolt from both sides of the A/C condenser.
4. Refill the A/C gas. Refer to REFRIGERANT RECOVERY AND RECHARGING.
5. Install the right upper radiator retaining bracket. Tighten: Tighten the upper right radiator retaining bracket bolt to 10 N.m (89 lb in).
6. Install the left upper radiator retaining bracket. Tighten: Tighten the left radiator retaining bracket to 10 N.m (89 lb in).
7. Install the return hose from the surge tank at the radiator.
8. Connect the lower radiator hose from the radiator.
9. Connect the upper cooling fan hose from the radiator.
10. Install the electric cooling fan. Refer to «Engine Coolant Fan Replacement»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
11. Refill the engine cooling system. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
12. Install the power steering oil tank. Refer to POWER STEERING FLUID RESERVOIR REPLACEMENT.
13. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection.

1. Disconnect the battery negative cable. Refer to «Battery Negative Cable Disconnection and Connection»(/chevrolet/aveo/i-2006-2012/remont/charging-system/#battery-charging-system-and-starting-system) .
2. Drain the engine cooling system. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
3. Remove the electric cooling fans. Refer to «Engine Coolant Fan Replacement»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Remove the upper radiator hose clamp.
5. Disconnect the upper radiator hose from the radiator.
6. Disconnect the lower radiator hose from the radiator.
7. Remove the lower radiator hose clamp.
8. Remove the hose clamp from the surge tank hose at the radiator.
9. Disconnect the surge tank hose from the radiator.
10. Remove the left upper radiator retaining bolt.
11. Remove the left upper radiator retaining bracket.
12. Remove the right upper radiator retaining bolt.
13. Remove the right upper radiator retaining bracket.
14. Remove the radiator from the vehicle.

1. Set the radiator into place in the vehicle with the radiator bottom posts in the rubber shock bumpers.
2. Position the radiator retainers in place.
3. Install the upper right radiator retaining bracket.
4. Install the upper right radiator retaining bolt and tighten to 7 N.m (62 lb in).
5. Install the upper left radiator retaining bracket.
6. Install the upper left radiator retaining bolt and tighten to 7 N.m (62 lb in).
7. Connect the surge tank hose to the radiator.
8. Secure the surge tank hose with a hose clamp.
9. Connect the upper radiator hose and the lower radiator hose to the radiator.
10. Secure each hose with a hose clamp.
11. Install the electric cooling fans. Refer to «Engine Coolant Fan Replacement»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system) .
12. Refill the engine cooling system. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
13. Connect the battery negative cable. Refer to «Battery Negative Cable Disconnection and Connection»(/chevrolet/aveo/i-2006-2012/remont/charging-system/#battery-charging-system-and-starting-system) .

1. Drain the cooling system. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .
2. Disconnect the coolant heater power supply cord from the coolant heater.
3. Remove the coolant heater and seal from the engine block.

1. Install the seal to the coolant heater.
2. Install the coolant heater in to the engine block and tighten to 60 N.m (44 lb ft).
3. Connect the coolant heater power supply cord to the coolant heater.
4. Fill the cooling system. Refer to «Cooling System Draining and Filling»(/chevrolet/aveo/i-2006-2012/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling) .

1. Disconnect the coolant heater power supply cord from the coolant heater (2).
2. Disconnect the coolant heater cord clip (1) from the engine lift bracket.
3. Disconnect the coolant heater cord from between the washer bottle and the coolant reservoir (1).
4. Remove the coolant heater cord from the vehicle.

1. Connect the coolant heater cord to the coolant heater (2).
2. Secure the coolant heater cord clip (1) to the engine lift bracket.
3. Route the coolant heater cord along the battery (2).
4. Secure the coiled power cord between the washer fluid bottle and the coolant reservoir (1).

Single Fan

The engine cooling fan system consists of an electric cooling fan, two fan relays and a fan resistor.

The engine control module (ECM) controls cooling fan operation in either high speed or low speed mode, depending on cooling requirements. To activate the fan, the ECM applies ground to the coil side of the applicable fan relay. This energizes the coil and pulls the switch side of the relay closed.

In low speed operation, the ECM applies ground to the coil side of the low speed FAN LOW relay. This energizes the coil and applies voltage directly to the engine cooling fan resistor through the switch side of the FAN LOW relay. The cooling fan resistor is connected in series to the engine cooling fan. The series circuit operates the fan at low speed.

In high speed operation, the ECM applies a ground to the coil side of the high speed FAN HI relay. When energized, the FAN HI relay supplies voltage directly to the cooling fan through the switch side of the relay. With a direct voltage supply and path to ground the fan operates at high speed.

The cooling fan will always operate anytime the A/C system is operating. First at low speed, and then at high speed when engine coolant temperature exceeds a specified value.

Dual Fans

The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series parallel (S/P) configuration that allows the engine control module (ECM) to operate both fans together at low or high speeds, depending on cooling requirements. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block.

In low speed operation, the ECM applies ground to the coil side of the low speed FAN LOW relay. This energizes the coil and applies voltage directly to the auxiliary cooling fan through the switch side of the FAN LOW relay. The fan is connected in series to the main cooling fan through the de-energized S/P FAN CNTRL relay. The series circuit operates both fans at low speed.

In high speed operation, the ECM applies a ground to the coil side of the FAN LOW relay, the S/P FAN CNTRL relay, and the high speed FAN HI relay. When energized, the FAN HI relay applies voltage directly to the main cooling fan through the switch side of the relay. Simultaneously, the FAN LOW relay and the S/P FAN CNTRL relay provide ignition voltage and a direct path to ground for the auxiliary cooling fan. With both fans connected in a parallel circuit, each fan receives full voltage and operates at high speed.

The cooling fans will always operate anytime the A/C system is operating. First at low speed, and then at high speed when engine coolant temperature exceeds a specified value.

Cooling System Description and Operation

The cooling system maintains the engine temperature at an efficient level during all engine operating conditions. When the engine is cold, the cooling system cools the engine slowly or not at all. This slow cooling of the engine allows the engine to warm up quickly.

The cooling system includes a radiator and recovery subsystem, cooling fans, a thermostat and housing, a coolant pump, and a coolant pump drive belt. The timing belt drives the coolant pump.

All components must function properly in order for the cooling system to operate. The coolant pump draws the coolant from the radiator. The coolant then circulates through water jackets in the engine block, the intake manifold, and the cylinder head. When the coolant reaches the operating temperature of the thermostat, the thermostat opens. The coolant then goes back to the radiator where it cools.

This system directs some coolant through the hoses to the heater core. This provides for heating and defrosting. The surge tank is connected to the radiator to recover the coolant displaced by expansion from the high temperatures. The surge tank maintains the correct coolant level.

The cooling system for this vehicle has no radiator cap or filler neck. The coolant is added to the cooling system through the surge tank.

Radiator

This vehicle has a lightweight tube-and-fin aluminum radiator. Two models of radiators are available: small, standard, and heavy duty. The 2 models vary only by capacity. Plastic tanks are mounted on the right and the left sides of the radiator core.

On vehicles equipped with automatic transaxles, the transaxle fluid cooler lines run through the left radiator tank. A radiator drain cock is on this radiator.

To drain the cooling system, open the drain cock.

Surge Tank

The surge tank is a transparent plastic reservoir, similar to the windshield washer reservoir.

The surge tank is connected to the radiator by a hose and to the engine cooling system by another hose. As the vehicle is driven, the engine coolant heats and expands. The portion of the engine coolant displaced by this expansion flows from the radiator and the engine into the surge tank. The air trapped in the radiator and the engine is degassed into the surge tank.

When the engine stops, the engine coolant cools and contracts. The displaced engine coolant is then drawn back into the radiator and the engine. This keeps the radiator filled with coolant to the desired level at all times and increases the cooling efficiency.

Maintain the coolant level between the MIN and the MAX marks on the surge tank when the system is cold.

Coolant Pump

The belt-driven centrifugal coolant pump consists of an impeller, a drive shaft, and a belt pulley. The coolant pump is mounted on the front of the transverse-mounted engine, and is driven by the timing belt.

The impeller is supported by a completely sealed bearing.

The coolant pump is serviced as an assembly and, therefore, cannot be disassembled.

Thermostat

A wax pellet-type thermostat controls the flow of the engine coolant through the engine cooling system. The thermostat is mounted in the thermostat housing to the front of the cylinder head.

The thermostat stops the flow of the engine coolant from the engine to the radiator to provide faster warm-up, and to regulate the coolant temperature. The thermostat remains closed while the engine coolant is cold, preventing circulation of the engine coolant through the radiator. At this point, the engine coolant is allowed to circulate only throughout the heater core to warm it quickly and evenly.

As the engine warms, the thermostat opens. This allows the engine coolant to flow through the radiator where the heat is dissipated through the radiator. This opening and closing of the thermostat permits enough engine coolant to enter the radiator to keep the engine within proper engine temperature operating limits.

The wax pellet in the thermostat is hermetically sealed in a metal case. The wax element of the thermostat expands when it is heated and contracts when it is cooled.

As the vehicle is driven and the engine warms, the engine coolant temperature increases. When the engine coolant reaches a specified temperature, the wax pellet element in the thermostat expands and exerts pressure against the metal case, forcing the valve open. This allows the engine coolant to flow through the engine cooling system and cool the engine.

As the wax pellet cools, the contraction allows a spring to close the valve.

The thermostat begins to open at 87°C (189°F) and is fully open at 102°C (216°F). The thermostat closes at 86°C (187°F).

Engine Coolant Temperature (ECT) Sensor

The engine coolant temperature (ECT) sensor uses a thermistor to control the signal voltage to the engine control module (ECM) and controls the instrument panel temperature indicator. The ECT sensor is located on the cylinder head. Refer to the appropriate engine controls section for diagnosis and replacement of the sensor.

Engine Block Heater

The vehicle is designed to accept an engine block heater. The engine block heater helps to warm the engine for improved cold weather starting. It can also help reduce fuel consumption when a cold engine is warming up.

The engine block heater utilizes an existing expansion plug for installation and is located in the engine block in an existing freeze plug port.

Contact your General Motors dealer for further information or installation.

Special Tools

Illustration Tool Number/ Description J-36649 Cooling System Pressure Test Adapter

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Component Connector End Views
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Powertrain Diagnostic Trouble Code (DTC) Type Definitions
• Control Module References
• Diagnostic Repair Verification
• Diagnostic Trouble Code (DTC) List - Vehicle
• Relay Replacement (Within an Electrical Center)
• Diagnostic Starting Point - Heating, Ventilation and Air Conditioning
• Headlamp Replacement (Notchback)
• Fastener Caution
• Radiator Cap Removal Warning
• Electric Coolant Fan Warning
• Battery Disconnect Warning
• Battery Negative Cable Disconnection and Connection
• DTC P00B3 or P00B4
• Thermostat Diagnosis
• Loss of Coolant
• Cooling System Description and Operation
• Engine Overheating
• Coolant Heater Inoperative
• Engine Fails To Reach Normal Operating Temperature
• Cooling System Draining and Filling
• Special Tools