Engine Cooling System Buick LaCrosse II рестайлинг

Fastener Tightening Specifications

Fastener Tightening Specifications

Adhesives, Fluids, Lubricants, and Sealers

Adhesives, Fluids, Lubricants, and Sealers

Scheme 1

Scheme 2

Scheme 3

Diagnostic Code Index

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

KR20C Cooling Fan Low Speed Relay

KR20D Cooling Fan High Speed Relay

KR20E Cooling Fan Speed Control Relay

KR20F Cooling Fan Relay

Circuit/System Description

The engine cooling fan system is composed of two fans, 7 relays, the engine control module (ECM), and the associated wiring. Each fan assembly includes one resistor, which enables the ECM to operate the engine cooling fans at 3 speeds using two control circuits. The ECM activates the applicable relay by grounding the control circuit with a solid state device called a driver. Each 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. The cooling fan and fan relays receive battery voltage from the underhood fuse block. The ground path for the operation of the cooling fan is provided at G106.

Conditions for Running the DTC

1. The ignition voltage is greater than 11 volts.
2. The ECM driver transitions from ON to OFF or from OFF to ON.
3. DTCs P0480, P0481, P0691, P0692, P0693, and P0694 run continuously when the conditions above are met.

Conditions for Setting the DTC

The commanded state of the ECM driver and the actual state of the control circuit do not match for greater than 5 seconds.

Action Taken When the DTC Sets

DTCs P0480, P0481, P0691, P0692, P0693, P0694 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0480, P0481, P0691, P0692, P0693, P0694 are Type B DTCs.

Diagnostic Aids

1. The ECM has the capability of providing command to the fan relays even when a scan tool output control is being used. Always refer to the fan control command parameters on the scan tool to know which fans are being commanded ON by the ECM.
2. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates both fans at a medium speed Cooling Fan Relays 2 and 3 operates both fans at a low speed Cooling Fan Relays 1, 2 and 3 operates both fans at a high speed
3. When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.
4. A condition with the powertrain relay may set DTC P0481 or P0693.

Reference Information

Schematic Reference

Engine Heating/Cooling Schematics

Connector End View Reference

1. «COMPONENT CONNECTOR END VIEWS - INDEX»(/buick/lacrosse/ii-2013-2016/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index)
2. «Electrical Center Identification Views»(/buick/lacrosse/ii-2013-2016/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-electrical-center-identification-views)

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__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. Ignition ON, verify an audible click is heard or felt from each cooling fan relay when commanding the cooling fans ON and OFF with a scan tool.
2. Engine operating, observe the DTC information with a scan tool. DTC P0480, P0481, P0691, P0692, P0693, or P0694 should not set.
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.

Circuit/System Testing

1. Ignition OFF, disconnect the KR20 Cooling Fan Relays listed below: KR20F Cooling Fan Relay KR20C Cooling Fan Low Speed Relay KR20D Cooling Fan High Speed Relay
2. Ignition ON, connect a test lamp between ground and the relay coil ignition voltage circuit terminal listed below. The test lamp should illuminate. KR20F Cooling Fan Relay terminal 85 KR20C Cooling Fan Low Speed Relay terminal 86 If the test lamp does not illuminate and the fuse is good Ignition OFF, and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Remove the test lamp. Test for less than 2 ohms in the ignition circuit of the appropriate relay, end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF, and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Remove the test lamp. Test for infinite resistance between the relay coil ignition circuits listed below and ground. KR20F Cooling Fan Relay terminal 85 KR20C Cooling Fan Low Speed terminal 86 If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance test all the appropriate cooling fan relays for a shorted condition and replace as necessary. If the test lamp illuminates
3. Connect a DMM, set on the diode setting, between ground and a relay control circuit terminal listed below: KR20F Cooling Fan Relay terminal 86 KR20C Cooling Fan Low Speed Relay terminal 85 KR20D Cooling Fan High Speed Relay terminal 85
4. Verify the DMM reading is greater than 2.5 V or displays O.L with the cooling fan relays commanded OFF with a scan tool. If 2.5 V or less Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module. Test for infinite resistance between the appropriate relay coil control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K20 Engine Control Module. If greater than 2.5 V or displays O.L.
5. Verify the DMM reading is less than 1 V when commanding the cooling fan relays ON with a scan tool. If 1 V or greater Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module, ignition ON. Test for less than 1 V between the appropriate cooling fan relay control circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V. Ignition OFF, and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 2 ohms in the appropriate cooling fan relay control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If less than 1 V
6. Test or replace the appropriate cooling fan relay.

Component Testing

1. Ignition OFF, disconnect a KR20 Cooling Fan Relay.
2. Test for 70-110 ohms between terminals 85 and 86, 95-135 ohms for the KR20F Cooling Fan Relay. If less than 70 ohms or greater than 110 ohms Replace the KR20 Cooling Fan Relay. If between 70-110 ohms
3. Test for infinite resistance between the terminals listed below. 30 and 86 30 and 87 30 and 85 85 and 87 If less than infinite resistance Replace the KR20 Cooling Fan Relay. If infinite resistance
4. Test for less than 2 ohms between terminals 3 and 4. If greater than 2 ohms Replace the KR20L Cooling Fan Speed Control 2 Relay. If less than 2 ohms
5. Connect a 20 A fused jumper wire between relay terminal 85 and B+. Connect a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than 2 ohms replace the KR20 Cooling Fan Relay.

KR20 Relay with Single Digit Terminal ID

1. Ignition OFF, disconnect the KR20 cooling fan relay.
2. Test for 70-110 ohms between terminals 1 and 2, 95-135 ohms for the KR20F Cooling Fan Relay. If less than 70 ohms or greater than 135 ohms Replace the KR20 Cooling Fan Relay. If between 70-135 ohms
3. Test for infinite resistance between the terminals listed below. 3 and 1 3 and 5 3 and 2 2 and 5 If less than infinite resistance Replace the KR20 Cooling Fan Relay. If infinite resistance
4. Test for less than 2 ohms between terminals 3 and 4. If greater than 2 ohms Replace the KR20L Cooling Fan Speed Control 2 Relay. If less than 2 ohms
5. Connect a 20 A fused jumper wire between relay terminal 2 and B+. Connect a jumper wire between relay terminal 1 and ground. Test for less than 2 ohms between terminals 3 and 5. If greater than 2 ohms replace the KR20 Cooling Fan Relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) , «Relay Replacement (Attached to Wire Harness)»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
2. «Control Module References»(/buick/lacrosse/ii-2013-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine cooling fan system consists of a cooling fan assembly containing two electric cooling fans. The engine control module (ECM) uses two fan control circuits and a series of three relays to command the fans ON in either high speed or low speed, depending on cooling requirements. The ECM activates the applicable relay by grounding the control circuit with a solid state device called a driver. Each 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. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.

1. The ignition voltage is greater than 11 volts.
2. The ECM driver transitions from ON to OFF or from OFF to ON.
3. DTCs P0480, P0481, P0691, P0692, P0693, and P0694 run continuously when the conditions above are met.

The commanded state of the ECM driver and the actual state of the control circuit do not match for greater than 5 seconds.

DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.

DTCs P0480, P0481, P0691, P0692, P0693, and P0694 are Type B DTCs.

1. The ECM has the capability of providing command to the fan relays even when a scan tool output control is being used. Always refer to the fan control command parameters on the scan tool to know which fans are being commanded ON by the ECM.
2. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates both fans at a low speed Cooling Fan Relays 2 and 3 operates one fan at a high speed Cooling Fan Relays 1, 2 and 3 operates both fans at a high speed

Schematic Reference

Engine Heating/Cooling Schematics

Connector End View Reference

1. «COMPONENT CONNECTOR END VIEWS - INDEX»(/buick/lacrosse/ii-2013-2016/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index)
2. «Electrical Center Identification Views»(/buick/lacrosse/ii-2013-2016/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-electrical-center-identification-views)

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__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.
2. Verify an audible click is heard or felt from each cooling fan relay when commanding the cooling fans ON and OFF with a scan tool. If a click is not heard or felt at one or more of the relays Refer to Circuit/System Testing (below). If a click is heard or felt at each of the relays
3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
4. Verify the DTC does not set. If the DTC sets Refer to Circuit/System Testing (below). If the DTC does not set
5. All OK.

1. Ignition OFF, disconnect all of the cooling fan relays. Ignition ON.
2. Verify that a test lamp illuminates between ground and a relay coil ignition circuit terminal listed below: KR20C Cooling Fan Low Speed Relay terminal 85/2 KR20D Cooling Fan High Speed Relay terminal 86/1 KR20E Cooling Fan Speed Control Relay terminal 86/1 If the test lamp does not illuminate Ignition OFF, and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Remove the test lamp. Test for less than 2 ohms in the ignition circuit of the appropriate cooling fan relay, end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF, and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Remove the test lamp. Test for infinite resistance between the appropriate cooling fan relay ignition circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance test or replace the appropriate cooling fan relay. If the test lamp illuminates
3. Ignition ON.
4. Connect a DMM, set on the diode setting, between ground and a relay control circuit terminal listed below: KR20C cooling fan low speed relay terminal 86/1 KR20D cooling fan high speed relay terminal 85/2 KR20E cooling fan speed control relay terminal 85/2
5. Verify the DMM reading is greater than 2.5 V or displays O.L with the cooling fan relays commanded OFF with a scan tool. If 2.5 V or less Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module. Test for infinite resistance between the appropriate relay coil control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K20 Engine Control Module. If greater than 2.5 V or displays O.L.
6. Verify the DMM reading is less than 1 V when commanding the cooling fan relays ON with a scan tool. If 1 V or greater Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module, ignition ON. Test for less than 1 V between the appropriate cooling fan relay control circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V. Ignition OFF, and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 2 ohms in the appropriate cooling fan relay control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If less than 1 V
7. Test or replace the appropriate cooling fan relay.

1. Ignition OFF.
2. Disconnect a cooling fan relay.
3. Test for 70-110 ohms between terminals 85/2 and 86/1. If less than 70 ohms or greater than 110 ohms Replace the cooling fan relay. If between 70-110 ohms
4. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 OR 3 and 2 3 and 5 3 and 1 1 and 5 If less than infinite resistance Replace the cooling fan relay. If infinite resistance
5. Test for less than 2 ohms between KR20E Cooling Fan Speed Control Relay terminals 30/3 and 87A/4. If 2 ohms or greater Replace the KR20E Cooling Fan Speed Control Relay. If less than 2 ohms
6. Install a 20 A fused jumper wire between relay terminal 85 or 2 and 12 V.
7. Install a jumper wire between relay terminal 86 or 1 and ground.
8. Test for less than 2 ohms between terminals 3/30 and 5/87. If 2 ohms or greater Replace the cooling fan relay. If less than 2 ohms
9. All OK.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) , «Relay Replacement (Attached to Wire Harness)»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
2. «Control Module References»(/buick/lacrosse/ii-2013-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) uses the engine coolant temperature sensor to monitor the engine for an over-temperature condition. This condition occurs when the coolant temperature is above a calibrated value. The ECM will alternately disable 2 groups of cylinders by turning OFF the fuel injectors. By switching between the 2 groups of cylinders, the ECM is able to reduce the temperature of the coolant.

1. The engine is operating for greater than 30 seconds.
2. DTC P1258 runs continuously once the conditions above have been met.

The ECM detects that engine coolant temperature is warmer than 131°C (268°F) for greater than 2 seconds.

1. DTC P1258 is a Type A DTC.
2. The engine will operate in the Overheated Engine Protection Operating Mode.
3. The IP will illuminate the coolant temperature indicator lamp and the driver information center (DIC), if equipped, may display a message.
4. If the protection mode is active and an ECT sensor DTC sets, the protection mode will remain active at the start of the next drive cycle until the ECT sensor DTC runs and passes.

DTC P1258 is a Type A DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

1. «Cooling Fan Description and Operation»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system__cooling-fan-description-and-operation)
2. «Instrument Cluster Description and Operation»(/buick/lacrosse/ii-2013-2016/remont/gauges-instrument-panels/#instrument-panel-system-displays-and-gauges)
3. «Indicator/Warning Message Description and Operation»(/buick/lacrosse/ii-2013-2016/remont/gauges-instrument-panels/#instrument-panel-system-displays-and-gauges)

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Wiring Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

K20 Engine Control Module: Scan Tool Information for scan tool information

Note. If DTC P0480, P0481, P0691, P0692, P0693, or P0694 is set, diagnose that DTC first.

1. Observe the engine coolant level. The engine coolant level should be within the operating range. Refer to «Cooling System Draining and Filling (Static Fill)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Ensure that the vehicle has the correct engine coolant with correct concentration and is not old, contaminated, or contains additives. Refer to «Cooling System Draining and Filling (Static Fill)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Inspect the cooling system for the following: Leaks Kinked or pinched hoses, especially at the radiator Loose, missing, or damaged radiator air seals or deflectors Air flow obstructions or bent fins at the radiator or the A/C condenser-Refer to «Symptoms - Engine Cooling»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Command the cooling fans ON and OFF, low and high speed. The engine cooling fans should turn ON and OFF with each command. If the cooling fans do not function as indicated, refer to «Cooling Fan Inoperative (LHU)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling Fan Inoperative (LUK or LFX)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Test the thermostat for correct operation. Refer to «Thermostat Diagnosis»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system__thermostat-diagnosis) .
2. Test the engine cooling system for overheating. Refer to «Engine Overheating»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system__engine-overheating) .
3. Inspect the water pump and coolant flow for correct operation. Refer to «Water Pump Cleaning and Inspection»(/buick/lacrosse/ii-2013-2016/remont/mechanical/#engine-mechanical-36l-lfx-repair-instructions-off-vehicle) .
4. Inspect the engine mechanical for worn, leaking, cracked cylinder heads or engine block. Refer to «Coolant in Engine Oil»(/buick/lacrosse/ii-2013-2016/remont/mechanical/#engine-mechanical-36l-lfx-diagnostic-information-and-procedures__coolant-in-engine-oil) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Important Preliminary Inspections Before Starting

Before using the Symptom diagnosis, perform the following

1. Perform «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) 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.
2. Verify the customer concern.
3. 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.
4. 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 , and Cooling System Description and Operation .

Visual/Physical Inspection

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

1. Ensure that the control module grounds are clean, tight, and correctly located.
2. Inspect cooling system hoses and pipes for splits, kinks, and improper connections. Inspect thoroughly for any type of leak or restriction.
3. Inspect for a dirty or restricted radiator or HVAC condenser.
4. Inspect for aftermarket devices which could affect the operation of the cooling system.
5. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
6. 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

1. Water intrusion in connectors, terminals, or components
2. Poor connector mating
3. Terminal contact
4. High circuit or component resistance-High resistance can include any resistance, regardless of the amount, which can interrupt the operation of the component.
5. Harness' that are routed too tight, or chaffed circuits
6. High or low ambient temperatures
7. High or low engine coolant temperatures
8. High underhood temperatures
9. Heat build up in components or circuits due to circuit resistance, poor terminal contact, or high electrical load
10. High or low system voltage
11. High vehicle load conditions
12. Rough road surface
13. Electro-magnetic interference (EMI)/circuit interference from relays, solenoids or other electrical surge
14. 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

1. «Cooling Fan Always On (LHU)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling Fan Always On (LUK or LFX)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Cooling Fan Inoperative (LHU)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling Fan Inoperative (LUK or LFX)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system)
3. «Engine Overheating»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system__engine-overheating)
4. «Loss of Coolant»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant)
5. «Thermostat Diagnosis»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system__thermostat-diagnosis)
6. «Engine Fails To Reach Normal Operating Temperature»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system)

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of the diagnostic category.

The engine cooling fan system is composed of two fans, 7 relays, the engine control module (ECM), and the associated wiring. Each fan assembly includes one resistor, which enables the ECM to operate the engine cooling fans at 3 speeds using two control circuits. The ECM activates the applicable relay by grounding the control circuit with a solid state device called a driver. Each 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. The cooling fan and fan relays receive battery voltage from the underhood fuse block. The ground path for the operation of the cooling fan is provided at G106.

1. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates both fans at a medium speed Cooling Fan Relay 2 and 3 operates both fans at a low speed Cooling Fan Relay 1, 2 and 3 operates both fans at a high speed
2. When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.

Schematic Reference

1. «Engine Heating/Cooling Schematics»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Electrical Center Identification Views»(/buick/lacrosse/ii-2013-2016/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-electrical-center-identification-views)

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the DTC information with a scan tool. Verify that DTCs P0480, P0481, P0691, P0692, P0693 or P0694 are not set. If any of the DTCs are set refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
2. Ignition ON, observe the scan tool Cooling Fan Relay 1 and Cooling Fan Relays 2 and 3 Command parameters. The parameters should display OFF.
3. Ignition ON, observe that the fans are not ON.

Both Fans ON

1. Ignition OFF, disconnect the KR20F cooling fan relay.
2. Ignition ON, verify that the cooling fans are not ON. If the cooling fans are OFF Test or replace KR20F relay. If the cooling fans are ON
3. Ignition OFF, disconnect the KR20C cooling fan low speed relay.
4. Ignition ON, verify that the cooling fans are not ON. If the cooling fans are OFF Test or replace KR20C relay. If the cooling fans are ON
5. Ignition OFF, disconnect the KR20M cooling fan left medium speed relay. If the cooling fans are OFF Test or replace KR20M relay. If the cooling fans are ON
6. Test for infinite resistance between ground and KR20F Cooling Fan Relay terminal 87. If less than infinite resistance repair the short to ground in the circuit If less than 1 V
7. Test for less than 1 V between ground and the relay terminals listed below KR20C Cooling Fan Low Speed Relay terminal 30 KR20M Cooling Fan Left Medium Speed Relay terminal 8 If greater than 1 V, repair the short to voltage on the appropriate circuit If less than 1 V
8. If all circuits test normal, test or replace the KR20M relay.

One Fan ON

1. Ignition OFF, disconnect the KR20D cooling fan high speed relay.
2. Ignition ON, verify that the cooling fan is not ON. If the cooling fans are OFF If the fan is OFF, test or replace KR20D relay. If the cooling fans are ON
3. Ignition OFF, disconnect the KR20N cooling fan right medium speed relay.
4. Ignition ON, verify that the cooling fan is not ON. If the cooling fans are OFF Test or replace KR20M relay. If the cooling fans are ON Test for less than 1 V between the relay circuit terminals listed below KR20D Cooling Fan High Speed Relay terminal 30 KR20N Cooling fan Right Medium Speed Relay terminal 8 If 1 V or greater repair the short to voltage on the circuit If the cooling fans are OFF
5. If all circuits test normal, test or replace the KR20N relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Relay Replacement (Within an Electrical Center) , Relay Replacement (Attached to Wire Harness)

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine cooling fan system consists of a cooling fan assembly containing two electric cooling fans. The engine control module (ECM) uses two fan control circuits and a series of three relays to command the fans ON in either high speed or low speed, depending on cooling requirements. The ECM activates the applicable relay by grounding the control circuit with a solid state device called a driver. Each 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. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.

1. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates both fans at a low speed Cooling Fan Relays 2 and 3 operates one fan at a high speed Cooling Fan Relays 1, 2 and 3 operates both fans at a high speed
2. Certain resistance conditions with IAT or ECT sensors may cause unwarranted cooling fan activation. If the ECM is commanding the cooling fans ON for no apparent reason and without any component or system DTCs set, the IAT or ECT sensor may be skewed. If this condition is suspected, refer to the temperature versus resistance tables in the appropriate Engine Controls subsection.

Schematic Reference

Engine Heating/Cooling Schematics

Connector End View Reference

1. «COMPONENT CONNECTOR END VIEWS - INDEX»(/buick/lacrosse/ii-2013-2016/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index)
2. «Electrical Center Identification Views»(/buick/lacrosse/ii-2013-2016/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-electrical-center-identification-views)

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON.
2. Verify that DTC P0480, P0481, P0691, P0692, P0693, or P0694 is not set. If a DTC is set Refer to «DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LHU)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LUK or LFX)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) . If no DTC is set
3. Verify the scan tool parameters listed below display OFF: Cooling Fan Relay 1 Command Cooling Fan Relays 2 and 3 Command If a scan tool parameter displays ON Refer to Diagnostic Aids and «Symptoms - Engine Cooling»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) for further diagnosis. If both scan tool parameters display OFF
4. Verify that the fans are not activated. If a fan is operating Refer to Circuit/System Testing (below). If both fans are OFF
5. All OK

Both Cooling Fans Always ON

1. Ignition OFF, disconnect KR20C Cooling Fan Low Speed Relay, ignition ON.
2. Verify that both cooling fans are OFF. If the cooling fans are ON Ignition OFF, disconnect the harness connector at the G10R Cooling Fan Motor-Right, ignition ON. Test for less than 1 V between KR20C Cooling Fan Low Speed Relay terminal 87/5 and ground. If 1 V or greater, repair the short to voltage in the relay controlled output circuit. If the cooling fans are OFF
3. Test or replace the KR20C Cooling Fan Low Speed Relay.

One Cooling Fan Always ON

1. Ignition OFF, disconnect the KR20D Cooling Fan High Speed Relay, ignition ON.
2. Verify the cooling fan is OFF. If the cooling fan is ON Ignition OFF, disconnect the harness connector at the G10L Cooling Fan Motor-Left, ignition ON. Test for less than 1 V between KR20D Cooling Fan High Speed Relay terminal 30/3 and ground. If 1 V or greater, repair the short to voltage in the relay controlled output circuit. If the cooling fan is OFF
3. Test or replace the KR20D Cooling Fan High Speed Relay.

1. Ignition OFF.
2. Disconnect a KR20 Cooling Fan Relay.
3. Test for 70-110 ohms between terminals 85/2 and 86/1. If less than 70 ohms or greater than 110 ohms Replace the KR20 cooling fan relay. If between 70-110 ohms
4. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 OR 3 and 2 3 and 5 3 and 1 1 and 5 If less than infinite resistance Replace the KR20 Cooling Fan Relay. If infinite resistance
5. Test for less than 2 ohms between KR20E Cooling Fan Speed Control Relay terminals 30/3 and 87A/4. If 2 ohms or greater Replace the KR20E Cooling Fan Speed Control Relay. If less than 2 ohms
6. Install a 20 A fused jumper wire between relay terminal 85 or 2 and 12 V.
7. Install a jumper wire between relay terminal 86 or 1 and ground.
8. Test for less than 2 ohms between terminals 3/30 and 5/87. If 2 ohms or greater Replace the KR20 Cooling Fan Relay. If less than 2 ohms
9. All OK.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Relay Replacement (Within an Electrical Center) , Relay Replacement (Attached to Wire Harness)

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine cooling fan system is composed of two fans, 7 relays, the engine control module (ECM), and the associated wiring. Each fan assembly includes one resistor, which enables the ECM to operate the engine cooling fans at 3 speeds using two control circuits. The ECM activates the applicable relay by grounding the control circuit with a solid state device called a driver. Each 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. The cooling fan and fan relays receive battery voltage from the underhood fuse block. The ground path for the operation of the cooling fan is provided at G106.

1. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates both fans at a medium speed Cooling Fan Relay 2 and 3 operates both fans at a low speed Cooling Fan Relay 1, 2 and 3 operates both fans at a high speed
2. When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.

Schematic Reference

Engine Heating/Cooling Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the DTC information with a scan tool. DTC P0480 or P0481, P0691, P0692, P0693, or P0694 should not set. If a DTC is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
2. Command the cooling fans ON and OFF at low, medium, and high speed with a scan tool. Both cooling fans should turn ON and OFF in each of the commanded states. Refer to «Diagnostic Aids»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Ignition OFF, disconnect the harness connectors, or remove the following components: KR20F Cooling Fan Relay KR20E Cooling Fan Speed Control Relay KR20L Cooling Fan Speed Control 2 Relay G10L Cooling Fan Motor-Left G10R Cooling Fan Motor-Right
2. Verify a test lamp illuminates between B+ and circuit terminal of the component listed below G10R Cooling Fan ground circuit terminal 3 KR20L Relay switched output circuit terminal 8 If the test lamp does not illuminate Test for less than 2 ohms in the appropriate ground circuit end to end. If less greater than 2 ohms, repair the open/high resistance in the circuit. If less than 2 ohms, repair the ground connection in the circuit. If the test lamp illuminates
3. Ignition ON, verify a test lamp illuminates between ground and the KR20 relay terminals listed below: KR20F relay terminal 85 KR20E relay terminal 86 and 30 If the test lamp does not illuminate and the fuse is good Ignition OFF, Disconnect the appropriate fuse. Test for less than 2 ohms between the fuse and the appropriate relay B+ end to end If greater than 2 ohms, repair the open/high resistance in the circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the fuse is open Ignition OFF, Disconnect the appropriate fuse. Test for infinite resistance between the appropriate relay terminal and ground If less than infinite resistance, repair the short to ground. If infinite resistance, test or replace the KR20L Cooling Fan Speed Control 2 Relay. If the test lamp illuminates
4. Ignition OFF, install the KR20F relay.
5. Connect a test lamp between B+ and the KR20E relay coil control circuit terminal 85.
6. Ignition ON, command the cooling fans ON at medium speed with a scan tool. The test lamp should illuminate. If the test lamp does not illuminate Test for less than 2 ohms between the Cooling Fan Relay terminals listed below: KR20F Cooling Fan Relay terminal 87 KR20E Cooling Fan Speed Control Relay terminal 85 If greater than 2 ohms, repair the open/high resistance in the circuit. If less than 2 ohms, Test or replace the KR20F Cooling Fan Relay If the test lamp illuminates
7. Ignition OFF, install the KR20E relay.
8. Remove the KR20D Cooling Fan High Speed Relay.
9. Connect a test lamp between ground and the KR20D relay coil ignition circuit terminal 86.
10. Ignition ON, command the cooling fans ON at medium speed with a scan tool. The test lamp should illuminate. If the test lamp does not illuminate Test for less than 2 ohms between the Cooling Fan Relay terminals listed below: KR20D Cooling Fan High Speed Relay terminal 86 KR20E Cooling Fan Speed Control Relay terminal 87 If greater than 2 ohms, repair the open/high resistance in the circuit. If less than 2 ohms, Test or replace the KR20E Cooling Fan High Speed Relay. If the test lamp illuminates
11. Ignition OFF, install the KR20D relay.
12. Ignition ON, Connect a test lamp between ground and the G10 cooling fan harness connector terminal listed below. Command the cooling fans ON at high speed with a scan tool. The test lamp should illuminate at each terminal as commanded. G10L Cooling Fan Motor-Left terminal 1 G10R Cooling Fan Motor-Right terminal 1 If the test lamp does not illuminate and the fuse is good Ignition OFF, test for less than 2 ohms in the B+ circuit of the appropriate G10 Cooling Fan Motor end to end. If greater than 2 ohms, repair the open/high resistance in the circuit If less than 2 ohms, test or replace the appropriate KR20 Cooling Fan Relay. If the test lamp does not illuminate and the fuse is open Ignition OFF, Test for infinite resistance between the appropriate G10 Cooling Fan terminal 1 and ground. If less than infinite resistance, repair the short to ground. If infinite resistance, test or replace the appropriate G10 Cooling Fan. If the test lamp illuminates
13. Ignition OFF, remove the following relays from the underhood relay block X70: KR20M Cooling Fan Left Medium Speed Relay KR20N Cooling Fan Right Medium Speed Relay
14. Ignition ON, connect a test lamp between ground and harness terminal 4 of each relay listed below. The test lamp should illuminate at each terminal. KR20M Cooling Fan Left Medium Speed Relay KR20N Cooling Fan Right Medium Speed Relay KR20L Cooling Fan Speed Control 2 Relay If the test lamp does not illuminate. Test for less than 2 ohms between the B+ fuse and terminal 4 of the appropriate Cooling Fan Relay If greater than 2 ohms, repair the open/high resistance in the circuit. If the test lamp illuminates
15. Connect a test lamp between B+ and harness terminal 6 of each relay listed below. Command the cooling fans ON at medium speed. The test lamp should illuminate at each terminal as commanded. KR20M Cooling Fan Left Medium Speed Relay KR20N Cooling Fan Right Medium Speed Relay KR20L Cooling Fan Speed Control 2 Relay If the test lamp does not illuminate. Test for less than 2 ohms between KR20F Cooling Fan Relay terminal 87 and the appropriate relay terminal listed below: KR20M Cooling Fan Left Medium Speed Relay terminal 6 KR20N Cooling Fan Right Medium Speed Relay terminal 6 KR20L Cooling Fan Speed Control 2 Relay terminal 6 If greater than 2 ohms, repair the open/high resistance in the circuit. If less than 2 ohms, test or replace the KR20F Cooling Fan Relay If the test lamp illuminates
16. Ignition OFF, install the following relays: KR20M Cooling Fan Left Medium Speed Relay KR20N Cooling Fan Right Medium Speed Relay
17. Ignition ON, Connect a test lamp between ground and the G10 cooling fan harness connector terminal listed below. Command the cooling fans ON at medium speed with a scan tool. The test lamp should illuminate at each terminal as commanded. G10L Cooling Fan Motor-Left terminal 2 G10R Cooling Fan Motor-Right terminal 2 If the test lamp does not illuminate Test for less than 2 ohms in the appropriate relay switched output circuit end to end. If greater than 2 ohms, repair the open/high resistance in the circuit. If less than 2 ohms, test or replace the KR20M or KR20N Cooling Fan Relay as appropriate. If the test lamp illuminates
18. Ignition OFF, Connect the harness connectors to the G10 cooling fans.
19. Connect a 40 A fused jumper wire between terminal 2 and terminal 8 of the KR20L Speed Control 2 Relay harness connector.
20. Ignition ON, command the cooling fans ON at high speed with a scan tool. Both fans should operate at full speed. If the left cooling fan does not operate. Test for less than 2 ohms between the circuit terminals listed below: G10L Cooling Fan Motor Left terminal 3 KR20L Cooling Fan Speed Control 2 Relay terminal 2 If greater than 2 ohms, repair the open/high resistance in the circuit. If less than 2 ohms, test or replace the G10L Cooling Fan Motor. If the right cooling fan does not operate Test or replace the G10R Cooling Fan Motor Right If both fans operate
21. Command the cooling fans ON at medium speed with a scan tool. Both fans should operate at a medium speed. If either fan does not operate Test or replace the appropriate G10 cooling fan motor.
22. Ignition OFF, remove the jumper wire and install the KR20L Speed Control 2 Relay.
23. Ignition ON, command the cooling fans ON at low speed with a scan tool. Both fans should operate at a reduced speed. If both fans are OFF Test or replace, the KR20L Cooling Fan Speed Control 2 Relay.
24. If all of the circuits test normal, test or replace the KR20L Speed Control 2 Relay.

1. Ignition OFF, disconnect a KR20 Cooling Fan Relay.
2. Test for 70-110 ohms between terminals 85 and 86, 95-135 ohms for the KR20F Cooling Fan Relay. If less than 70 ohms or greater than 110 ohms Replace the KR20 Cooling Fan Relay. If between 70-110 ohms
3. Test for infinite resistance between the terminals listed below. 30 and 86 30 and 87 30 and 85 85 and 87 If less than infinite resistance Replace the KR20 Cooling Fan Relay. If infinite resistance
4. Test for less than 2 ohms between terminals 3 and 4. If greater than 2 ohms Replace the KR20L Cooling Fan Speed Control 2 Relay. If less than 2 ohms
5. Connect a 20 A fused jumper wire between relay terminal 85 and B+. Connect a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than 2 ohms replace the KR20 Cooling Fan Relay.

G10 Engine Cooling Fan

1. Ignition OFF, disconnect the harness connector at the G10 engine cooling fan.
2. Connect a jumper wire between ground and the G10 ground circuit terminal 3.
3. Connect a 40 A fused jumper wire between B+ and the G10 fan B+ supply circuit terminal 1. The cooling fan should operate at a High speed. If the cooling fan does not operate Replace the G10 engine cooling fan. If the cooling fan operates
4. Connect a 40 A fused jumper wire between B+ and the G10 fan B+ supply circuit terminal 2. The cooling fan should operate at a reduced speed. If the cooling fan does not operate Replace the G10 engine cooling fan.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) , «Relay Replacement (Attached to Wire Harness)»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
2. «Engine Coolant Fan Motor Replacement»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system)

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine cooling fan system consists of a cooling fan assembly containing two electric cooling fans. The engine control module (ECM) uses two fan control circuits and a series of three relays to command 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.

1. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates both fans at a low speed Cooling Fan Relays 2 and 3 operates one fan at a high speed Cooling Fan Relays 1, 2 and 3 operates both fans at a high speed

Schematic Reference

Engine Heating/Cooling Schematics

Connector End View Reference

1. «COMPONENT CONNECTOR END VIEWS - INDEX»(/buick/lacrosse/ii-2013-2016/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index)
2. «Electrical Center Identification Views»(/buick/lacrosse/ii-2013-2016/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-electrical-center-identification-views)

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON.
2. Verify that DTC P0480, P0481, P0691, P0692, P0693, or P0694 is not set. If a DTC is set Refer to «DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LHU)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LUK or LFX)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) . If no DTCs is set
3. Verify that both cooling fans turn ON and OFF and operate at low and high speed, when commanding the appropriate cooling fan relays ON and OFF with a scan tool. If a cooling fan does not operate Refer to Circuit/System Testing (below). If both cooling fans operate
4. All OK.

1. Ignition OFF, disconnect all of the KR20 Cooling Fan Relays.
2. Verify a test lamp illuminates between ground and the B+ circuit terminals listed below: KR20C Cooling Fan Low Speed B+ circuit terminal 30/3 KR20D Cooling Fan High Speed B+ circuit terminal 87/5 If the test lamp does not illuminate and the circuit fuse is good Disconnect the appropriate cooling fan fuse. Test for less than 2 ohms between the fuse and the appropriate relay B+ circuit terminal, end to end. If 2 ohms or greater, repair the open/high resistance in the B+ circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Connect a DMM to the appropriate relay B+ circuit terminal. Test for infinite resistance between the B+ circuit and ground. If less than infinite resistance, repair the short to ground on the B+ circuit. If infinite resistance Disconnect the harness connector at the appropriate G10 Cooling Fan Motor. Test for infinite resistance between the appropriate relay controlled output circuit terminal 87/5 and ground. KR20C Cooling Fan Low Speed output circuit terminal 87/5 KR20D Cooling Fan High Speed output circuit terminal 30/3 If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, test or replace the appropriate G10 Cooling Fan Motor. If the test lamp illuminates
3. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the G10L Cooling Fan Motor-Left. It may take up to 2 minutes for all vehicle systems to power down.
4. Test for less than 5 ohms between the circuits listed below and ground: G10L Cooling Fan Motor-Left terminal A KR20E Cooling Fan Speed Control Relay terminal 87/5 If 5 ohms or greater Ignition OFF and all vehicle systems OFF, it may take up to 2 minutes for all vehicle systems to power down. Test for less than 2 ohms in the appropriate ground circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If less than 5 ohms
5. Connect the harness connector at the G10L Cooling Fan Motor-Left.
6. Connect a 50 A fused jumper between the KR20D Cooling Fan High Speed Relay terminals 30/3 and 87/5.
7. Verify the G10L Cooling Fan Motor-Left is activated at high speed. If the cooling fan does not activate Disconnect the harness connector at the G10L Cooling Fan Motor-Left. Test for less than 2 ohms in the circuit between KR20D Cooling Fan High Speed Relay terminal 30/3 and the G10L Cooling Fan Motor-Left terminal B. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the G10L Cooling Fan Motor-Left. If the cooling fan activates
8. Connect a fused jumper between the KR20E Cooling Fan Speed Control Relay switch circuit terminal 30/3 and the ground circuit terminal 87/5.
9. Connect a 40 A fused jumper between the KR20C Cooling Fan Low Speed Relay terminals 30/3 and 87/5.
10. Verify the G10R Cooling Fan Motor-Right is activated at high speed. If the cooling fan does not activate Disconnect the harness connector at the G10R Cooling Fan Motor-Right. Test for less than 2 ohms in the circuit between KR20C Cooling Fan Low Speed Relay terminal 87/5 and the G10R Cooling Fan Motor-Right terminal B. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms Test for less than 2 ohms in the circuit between KR20E Cooling Fan Speed Control Relay terminal 30/3 and the G10R Cooling Fan Motor-Right terminal A. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the G10R Cooling Fan Motor-Right. If the cooling fan activates
11. Install the KR20E Cooling Fan Speed Control Relay.
12. Verify both fan motors activate at low speed. If both cooling fans do not activate at low speed Disconnect both cooling fan motor harness connectors and the KR20E Cooling Fan Speed Control Relay. Test for less than 2 ohms in circuit between KR20E Cooling Fan Speed Control Relay terminal 87A/4 and the G10L Cooling Fan Motor-Left terminal B. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms Test for infinite resistance between KR20E Cooling Fan Speed Control Relay terminal listed below and ground. KR20E Cooling Fan Speed Control Relay terminal 30/3 KR20E Cooling Fan Speed Control Relay terminal 87A/4 If less than infinite, repair the short to ground in the circuit. If infinite, replace the KR20E cooling fan speed control relay. If both cooling fans activate
13. Test or replace the cooling fan relay listed below as appropriate: KR20C Cooling Fan Low Speed Relay KR20D Cooling Fan High Speed Relay

1. Ignition OFF.
2. Disconnect a KR20 Cooling Fan Relay.
3. Test for 70-110 ohms between terminals 85/2 and 86/1. If less than 70 ohms or greater than 110 ohms Replace the KR20 cooling fan relay. If between 70-110 ohms
4. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 OR 3 and 2 3 and 5 3 and 1 1 and 5 If less than infinite resistance Replace the KR20 Cooling Fan Relay. If infinite resistance
5. Test for less than 2 ohms between KR20E Cooling Fan Speed Control Relay terminals 30/3 and 87A/4. If 2 ohms or greater Replace the KR20E Cooling Fan Speed Control Relay. If less than 2 ohms
6. Install a 20 A fused jumper wire between relay terminal 85 or 2 and 12 V.
7. Install a jumper wire between relay terminal 86 or 1 and ground.
8. Test for less than 2 ohms between terminals 3/30 and 87/5. If 2 ohms or greater Replace the KR20 Cooling Fan Relay. If less than 2 ohms
9. All OK.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) , «Relay Replacement (Attached to Wire Harness)»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
2. «Engine Coolant Fan Shroud Replacement»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system__engine-coolant-fan-shroud-replacement)

Engine Overheating

Engine Overheating

Loss of Coolant

Loss of Coolant

Thermostat Diagnosis

Thermostat Diagnosis

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2013-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The coolant heater is a 300 watt heating element that mounts to the engine block. The coolant heater operates using 120 V AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather. The coolant heater also helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. There is an internal thermal switch in the coolant heater cord that prevents operation above -18°C (0°F). A weather shield on the cord is provided to protect the plug when not in use.

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2013-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Note. The coolant heater cord will read Open due to an internal thermal switch if the ambient temperature is above -18°C (0°F).

1. Ignition OFF, disconnect the coolant heater cord from the E19 Coolant Heater.
2. Test for 40-55 ohms between the terminals of the E19 Coolant Heater. If not within 40-55 ohms Replace the E19 Coolant Heater. If within 40-55 ohms
3. Test for infinite resistance between each terminal of the E19 Coolant Heater and ground. If less than infinite resistance Replace the E19 Coolant Heater. If infinite resistance
4. Test or replace the coolant heater cord.

Perform the Diagnostic Repair Verification after completing the diagnostic repair.

Special Tools

GE 24731 Tempil Stick

For equivalent regional tools, refer to Special Tools .

Use one of the following procedures in testing for a malfunctioning thermostat.

Thermostat Test Procedure Using Tempil Sticks

The coolant thermostat can be tested using a temperature (tempil) stick. The temperature stick is a pencil like device. It has a wax material containing certain chemicals which melt at a given temperature. Take a 87°C (188°F) tempil stick or a 97°C (206°F) tempil stick and rub it on the thermostat housing. Temperature sticks can be used to determine a thermostat's operating range.

1. Use a GE 24731 Tempil Stick in order to find the opening and the closing temperatures of the coolant thermostat. The 188 tempil stick melts at 87°C (188°F). The thermostat should begin to open. The 206 tempil stick melts at 97°C (206°F). The thermostat should be fully open.
2. Replace the coolant thermostat if it does not operate properly between this temperature range.

Thermostat Test Procedure Using Glycol

Inspect the operation of the thermostat by hanging the thermostat on a hook in a 50/50 percent solution of DEX-COOL® and clean drinkable water.

In order to inspect if the thermostat valve is opening properly, perform the following test

1. Completely submerge the thermostat in the glycol solution. The solution should be 11°C (22°F) above the temperature indicated on the thermostat valve.
2. Thoroughly agitate the solution. Under these conditions, the thermostat valve should open.

In order to inspect if the thermostat valve is closing properly, perform the following test

1. Completely submerge the thermostat in a glycol solution. The solution should be 6°C (10°F) below the temperature indicated on the thermostat valve.
2. Thoroughly agitate the solution. Under these conditions, the thermostat valve should close completely.

1. EN-24460-A Cooling System Pressure Tester
2. GE-42401-A Radiator Cap / Surge Tank Test Adapter

For equivalent regional tools, Refer to Special Tools

Pressure Cap Testing

1. Remove the pressure cap.
2. Wash the pressure cap sealing surface with water.
3. Use the EN-24460-A Cooling System Pressure Tester (1) with GE-42401-A Radiator Cap / Surge Tank Test Adapter (2) in order to test the pressure cap.
4. Test the pressure cap for the following conditions: Pressure release when the EN-24460-A Cooling System Pressure Tester exceeds the pressure rating of the pressure cap. Maintain the rated pressure for at least 10 seconds. Note the rate of pressure loss.
5. Replace the pressure cap under the following conditions: The pressure cap does not release pressure which exceeds the rated pressure of the cap. The pressure cap does not hold the rated pressure.

1. EN-24460-A Cooling System Pressure Tester
2. GE-42401-3 Radiator Cap / Surge Tank Test Adapter

For equivalent regional tools, Refer to Special Tools

Cooling System Leak Testing

1. Remove the pressure cap.
2. Test the operation of the pressure cap. Refer to «Pressure Cap Testing»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system__pressure-cap-testing) .
3. Wash the pressure cap mating surface with water.
4. Use the EN-24460-A Cooling System Pressure Tester (1) with GE-42401-3 Radiator Cap / Surge Tank Test Adapter (2) in order to apply pressure to the cooling system. Do not exceed the pressure cap rating.
5. The cooling system should hold the rated pressure for at least 2 minutes. Observe the gauge for any pressure loss.
6. Repair any leaks as required.

J 26568 Coolant and Battery Fluid Tester

Draining Procedure

1. Remove the coolant pressure cap from the radiator surge tank.
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/ii-2013-2016/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) .
3. Place a drain pan under the drain cock.
4. Loosen the radiator drain cock.
5. Drain the cooling system.
6. Lower the vehicle.
7. Inspect the coolant.
8. Follow the appropriate procedure based on the condition of the coolant. Normal in appearance-Follow the filling procedure. Discolored-Follow the flush procedure. Refer to «Flushing»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system__flushing) .

Filling Procedure

1. Raise and support the vehicle.
2. Tighten the radiator drain cock to 2 N.m (18 lb in).
3. Lower the vehicle.
4. Slowly fill the radiator with a 50/50 coolant mixture until the coolant level reaches the base of the radiator surge tank. Refer to «Approximate Fluid Capacities»(/buick/lacrosse/ii-2013-2016/remont/lubrication-system/#maintenance-and-lubrication__approximate-fluid-capacities) .
5. Allow 30 seconds for the coolant level to stabilize and continue to fill the coolant filler neck until the level stabilizes for at least 2 minutes.
6. Start the engine and allow to the engine to idle in PARK or NEUTRAL with the parking brake engaged.
7. Slowly fill the coolant mixture until the level stabilizes at the base of the radiator surge tank.
8. Install the coolant pressure cap.
9. Raise the engine RPM to 2500 rpm for 30-40 seconds.
10. Shut the engine OFF.
11. Allow the engine to cool, remove coolant fill cap and repeat steps 4-10 until the coolant level has completely stabilized within the radiator surge tank.
12. Inspect the concentration of the engine coolant using the J 26568 Coolant and Battery Fluid Tester
13. Inspect and if necessary, fill the coolant reservoir bottle as necessary.
14. Rinse away any excess coolant from the engine and the engine compartment
15. Inspect the cooling system for leaks.
16. Top off the radiator surge tank if necessary.

1. J 26568 Coolant and Battery Fluid Tester
2. J 42401 Radiator Cap and Surge Tank Test Adapter
3. GE-47716 Vac N Fill Coolant Refill Tool

1. Remove the coolant pressure cap.
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/ii-2013-2016/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) .
3. Place a drain pan under the drain cock.
4. Remove the radiator drain cock.
5. Drain the cooling system.
6. Lower the vehicle.
7. Inspect the coolant.
8. Follow the appropriate procedure based on the condition of the coolant. Normal in appearance-Follow the filling procedure. Discolored-Follow the flush procedure. Refer to «Flushing»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system__flushing) .

Vac-N-Fill Procedure

1. Install the J 42401 Radiator Cap and Surge Tank Test Adapter onto the coolant surge tank.
2. Attach the Vac N Fill cap to the J 42401 Radiator Cap and Surge Tank Test Adapter.
3. Attach the vacuum gauge assembly to the Vac N Fill cap.
4. Attach the fill hose to the barb fitting on the vacuum gauge assembly. Ensure that the valve is closed.
5. Pour the coolant mixture into the graduated reservoir.
6. Place the fill hose in the graduated reservoir.
7. Install the vacuum tank on the graduated reservoir with the fill hose routed through the cut-out area in the vacuum tank.
8. Attach the venturi assembly to the vacuum tank.
9. Attach a shop air hose to the venturi assembly. Ensure the valve on the venturi assembly is closed.
10. Attach the vacuum hose to the vacuum gauge assembly and the vacuum tank.
11. Open the valve on the venturi assembly. The vacuum gauge will begin to rise and a hissing noise will be present.
12. Continue to draw vacuum until the needle stops rising. This should be 610-660 mm Hg (24-26 in Hg). Cooling hoses may start to collapse. This is normal due to vacuum draw.
13. To aid in the fill process, position the graduated reservoir above the coolant fill port.
14. Slowly open the valve on the vacuum gauge assembly. When the coolant reaches the top of the fill hose, close the valve. This will eliminate air from the fill hose.
15. Close the valve on the venturi assembly.
16. If there is a suspected leak in the cooling system, allow the system to stabilize under vacuum and monitor for vacuum loss. If vacuum loss is observed, refer to «Loss of Coolant»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant) .
17. Open the valve on the vacuum gauge assembly. The vacuum gauge will drop as coolant is drawn into the system.
18. Once the vacuum gauge reaches zero, close the valve on the vacuum gauge assembly and repeat steps 11-17.
19. Detach the Vac N Fill cap from the J 42401 Radiator Cap and Surge Tank Test Adapter.
20. Remove the J 42401 Radiator Cap and Surge Tank Test Adapter from the coolant surge tank.
21. Add coolant to the system as necessary.
22. Inspect the concentration of the coolant mixture using J 26568 Coolant and Battery Fluid Tester.
23. Detach the vacuum hose from the vacuum gauge assembly.
24. Attach the extraction hose to the vacuum hose.
25. Open the valve on the venturi assembly to start a vacuum draw.
26. Use the extraction hose to draw out coolant to the proper level.
27. The vacuum tank has a drain valve on the bottom of the tank. Open the valve to drain coolant from the vacuum tank into a suitable container for disposal.
28. Install the surge tank cap.

Flushing

Note. Do not use a chemical flush. Store used coolant in the proper manner, such as in a used engine coolant holding tank. Do not pour used coolant down a drain. Ethylene glycol antifreeze is a very toxic chemical. Do not dispose of coolant into the sewer system or ground water. This is illegal and ecologically unsound. Various methods and equipment can be used to flush the cooling system. If special equipment is used, such as a back flusher, follow the manufacturer's instruction. Always remove the thermostat before flushing the cooling system.

When the cooling system becomes contaminated, the cooling system should be flushed thoroughly to remove the contaminants before the engine is seriously damaged.

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the radiator surge tank. Refer to «Radiator Surge Tank Replacement»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Clean and flush the radiator surge tank with clean, drinkable water.
4. Install the radiator surge tank. Refer to «Radiator Surge Tank Replacement»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Follow the drain and fill procedure using only clean, drinkable water. Refer to «Cooling System Draining and Filling (Static Fill)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
6. Run the engine for 20 minutes.
7. Stop the engine.
8. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system)
9. Repeat the procedure if necessary, until the fluid is nearly colorless.
10. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 4

Radiator Surge Tank Replacement

Scheme 5

Radiator Surge Tank Inlet Hose Replacement (LFX)

Scheme 6

Radiator Surge Tank Outlet Hose Replacement (LFX)

Scheme 7

Radiator Surge Tank Outlet Hose Replacement (LUK)

Scheme 8

Radiator Inlet Hose Replacement (LFX)

Scheme 9

Radiator Inlet Hose Replacement (LUK)

Scheme 10

Radiator Outlet Hose Replacement (LFX)

Scheme 11

Radiator Outlet Hose Replacement (LUK)

Repair Procedure

1. Pressure test the cooling system. Refer to «Cooling System Leak Testing»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-leak-testing) .
2. Grind the fracture surface (1) with a proper tool.
3. Drill a hole in the center of the fractured surface, using a 6 mm (0.24 in) drill.
4. Install the new radiator mounting pin (2). Install the nut (3). NOTE: The bolt should not be longer than 35 mm (1.38 in). Install the radiator mounting pin (2) with the bolt (1).
5. Tighten the bolt 5 N.m (45 lb in).

Scheme 12

Radiator Lower Mount Replacement

Scheme 13

Radiator Upper Mount Replacement

Scheme 14

Radiator Upper Bracket Replacement

Scheme 15

Engine Coolant Fan Motor Replacement

Scheme 16

Cooling Fan and Shroud Replacement

Removal Procedure

1. Remove the front exhaust pipe. Refer to «Exhaust Front Pipe Replacement (LFX)»(/buick/lacrosse/ii-2013-2016/remont/exhaust/#engine-exhaust-system) , «Exhaust Front Pipe Replacement (LUK)»(/buick/lacrosse/ii-2013-2016/remont/exhaust/#engine-exhaust-system) .
2. Remove the catalytic converter. Refer to «Catalytic Converter Replacement (LUK)»(/buick/lacrosse/ii-2013-2016/remont/exhaust/#engine-exhaust-system) .
3. Remove the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/buick/lacrosse/ii-2013-2016/remont/mechanical/#engine-mechanical-24l-luk) .
4. Disconnect the power brake booster vacuum pipe (1).
5. Detach the power brake booster vacuum pipe retainers (1).
6. Disconnect the EVAP canister vacuum pipe connector (1).
7. Remove the drive motor generator battery high voltage cable retainers (1) and reposition the high voltage cable (2).
8. Remove the heater outlet bracket.
9. Disconnect the camshaft position sensor and reposition the engine harness.
10. Disconnect the following hoses: Heater coolant pump hose (1) Heater inlet hose (2) Radiator outlet hose (3) Surge tank hose (4)
11. Disconnect the engine coolant temperature sensor (1).
12. Remove the engine coolant thermostat housing fasteners (2).
13. Discard the thermostat housing seal (4).
14. Remove the engine coolant thermostat housing with the outlet pipe from the water pump.

Installation Procedure

1. Clean the sealing surface.
2. Install NEW seals to the water pump outlet pipe and thermostat housing inlet pipe.
3. Install the engine coolant thermostat housing (2) to the engine block with a NEW seal (4).
4. Install the 3 fasteners (3) to the thermostat housing and tighten to 10 N.m (89 lb in).
5. Connect the electrical connector of the engine coolant temperature sensor (1).
6. Install the following hoses to the thermostat housing: Heater coolant pump hose (1) Heater inlet hose (2) Radiator outlet hose (3) Surge tank hose (4)
7. Attach the drive motor generator battery high voltage cable retainers (1) and reposition the high voltage cable (2).
8. Install the heater outlet bracket.
9. Connect the camshaft position sensor and reposition the engine harness.
10. Connect the power brake booster vacuum pipe (1).
11. Attach the power brake booster vacuum pipe retainers (1).
12. Connect the EVAP canister vacuum pipe connector (1).
13. Install the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/buick/lacrosse/ii-2013-2016/remont/mechanical/#engine-mechanical-24l-luk) .
14. Install the catalytic converter. Refer to «Catalytic Converter Replacement (LUK)»(/buick/lacrosse/ii-2013-2016/remont/exhaust/#engine-exhaust-system) .
15. Install the front exhaust pipe. Refer to «Exhaust Front Pipe Replacement (LFX)»(/buick/lacrosse/ii-2013-2016/remont/exhaust/#engine-exhaust-system) , «Exhaust Front Pipe Replacement (LUK)»(/buick/lacrosse/ii-2013-2016/remont/exhaust/#engine-exhaust-system) .

Scheme 17

Engine Coolant Thermostat Housing Replacement (LFX)

Scheme 18

Engine Coolant Thermostat Replacement (V6)

BO 38185 Hose Clamp Pliers

For equivalent regional tools refer to Special Tools .

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Reposition the engine control module.
3. Remove the surge tank hose (1) and the radiator outlet hose (2), from the water inlet housing (3).
4. Remove the water inlet fasteners (1) and remove the water inlet housing (2).
5. Remove the engine coolant thermostat (3) and discard the seal (4).
6. Carefully clean the water inlet sealing surfaces.

1. Install the thermostat (3) with a NEW seal (4).
2. Install the water inlet housing (2) and tighten the fasteners (1) to 10 N.m (89 lb in).
3. Install the radiator outlet hose (2) and the surge tank hose (1).
4. Reposition the engine control module on the battery tray.
5. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 19

Engine Coolant Air Bleed Pipe Replacement (V6)

Scheme 20

Water Outlet Replacement (V6)

EN-43651 Water Pump Holding Tool

For equivalent regional tools, refer to Special Tools .

1. Remove the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/buick/lacrosse/ii-2013-2016/remont/testing-diagnostics/#engine-controls-and-fuel-24l-luk-repair-instructions) .
2. Remove the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/buick/lacrosse/ii-2013-2016/remont/mechanical/#engine-mechanical-24l-luk) .
3. Remove the exhaust manifold heat shield. Refer to «Exhaust Manifold Heat Shield Replacement (LUK)»(/buick/lacrosse/ii-2013-2016/remont/exhaust/#engine-exhaust-system) .
4. If equipped, remove the coolant heater.
5. Remove the catalytic converter. Refer to «Catalytic Converter Replacement (LUK)»(/buick/lacrosse/ii-2013-2016/remont/exhaust/#engine-exhaust-system) .
6. Remove the engine coolant thermostat housing. Refer to «Engine Coolant Thermostat Housing Replacement (LUK)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Engine Coolant Thermostat Housing Replacement (LFX)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
7. Remove the water pump cover (2), fasteners (3) and gasket (1) from the engine front cover.
8. Drain the coolant from the water pump using the plug at the bottom of the pump. Install the plug when finished.
9. Align the EN-43651 water pump holding tool (1) with the threads on the water pump sprocket. Tighten the water pump holding tool fasteners (2).
10. Secure the water pump holding tool with the previously removed water pump cover fasteners (1) into the engine front cover.
11. Remove the water pump sprocket to water pump fasteners (1).
12. Remove the front water pump fasteners (1).
13. Remove the rear water pump fasteners (1).
14. Remove the water pump (1).
15. If replacing the water pump cover remove the water pump rear cover fasteners (4).
16. Separate the water pump cover (1) from the water pump (3).
17. Remove and discard the water pump O-ring seal (2).

1. If replacing the water pump cover (1), install a new O-ring (2) to the water pump (3) and tighten the fasteners (4) to 25 N.m (18 lb ft).
2. Using a guide pin (2), align the pin with the water pump holding tool.
3. Position the water pump (1) against the engine block and hand tighten the water pump fasteners (3).
4. Install 2 water pump sprocket to water pump fasteners (1). After the fasteners are snug, remove the guide pin (2) and install the 3rd fastener (3) and tighten to 10 N.m (89 lb in).
5. Install the water pump fasteners (1) at the front of the engine. Hand tighten at this time.
6. Tighten the water pump fasteners at the front and rear of the water pump to 25 N.m (18 lb ft).
7. Remove the water pump cover fasteners (1) from the engine front cover and water pump holding tool.
8. Remove the EN-43651 water pump holding tool (1) from the water pump sprocket.
9. Install the water pump access plate (2) gasket (1) and fasteners (3) and tighten to 10 N.m (89 lb in).
10. If equipped, Install the coolant heater.
11. Install the engine coolant thermostat housing. Refer to «Engine Coolant Thermostat Housing Replacement (LUK)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Engine Coolant Thermostat Housing Replacement (LFX)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
12. Install the catalytic converter. Refer to «Catalytic Converter Replacement (LUK)»(/buick/lacrosse/ii-2013-2016/remont/exhaust/#engine-exhaust-system) .
13. Install the exhaust manifold heat shield. Refer to «Exhaust Manifold Heat Shield Replacement (LUK)»(/buick/lacrosse/ii-2013-2016/remont/exhaust/#engine-exhaust-system) .
14. Install the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/buick/lacrosse/ii-2013-2016/remont/mechanical/#engine-mechanical-24l-luk) .
15. Install the air cleaner assembly. Refer to «Air Cleaner Assembly Replacement»(/buick/lacrosse/ii-2013-2016/remont/testing-diagnostics/#engine-controls-and-fuel-24l-luk-repair-instructions) .
16. Refill the coolant system. Refer to «Cooling System Draining and Filling (Static Fill)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .

EN 46104 Water Pump Pulley Holder

For equivalent regional tools refer to Special Tools

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the generator drive belt. Refer to «Drive Belt Replacement»(/buick/lacrosse/ii-2013-2016/remont/mechanical/#engine-mechanical-36l-lfx-repair-instructions-on-vehicle) .
3. Use the EN 46104 water pump pulley holder (1) to retain the pulley.
4. Remove the water pump pulley bolts and DISCARD the bolts.
5. Remove the water pump pulley.
6. Remove the water pump bolts and DISCARD the bolts.
7. Remove the water pump.
8. Remove and DISCARD the water pump seal.
9. Carefully clean the water pump sealing surfaces.

1. Install a NEW water pump seal.
2. Install the water pump.
3. Install the NEW water pump bolts and hand tighten the water pump bolts.
4. Tighten the water pump bolts in sequence. On the initial pass, tighten the bolts in sequence to 10 (89 lb in). On the second pass, tighten the bolts in sequence to 10 (89 lb in). On the final pass, tighten the bolts in sequence shown an additional 45 degrees.
5. Install the water pump pulley and the NEW water pump pulley bolts.
6. Use the EN 46104 water pump pulley holder (1) to hold the pulley.
7. Install the water pump pulley bolts and tighten to 12 (108 lb in).
8. Install the generator drive belt. Refer to «Drive Belt Replacement»(/buick/lacrosse/ii-2013-2016/remont/mechanical/#engine-mechanical-36l-lfx-repair-instructions-on-vehicle) .
9. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/buick/lacrosse/ii-2013-2016/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 21

Auxiliary Water Pump Replacement (LUK)

Scheme 22

Radiator Drain Cock Replacement

Engine Coolant Fan Shroud Replacement

Engine Coolant Fan Shroud Replacement

Scheme 23

Radiator Replacement (LFX, LUK)

Scheme 24

Radiator Support Bracket Replacement

Scheme 25

Radiator Air Side Baffle and Deflector Replacement (Left)

Scheme 26

Radiator Air Side Baffle and Deflector Replacement (Right)

Scheme 27

Radiator Air Upper Baffle and Deflector Replacement

Scheme 28

Engine Coolant Heater Replacement (LUK)

Scheme 29

Engine Coolant Heater Replacement (LFW)

Scheme 30

Coolant Heater Cord Replacement (LUK)

Scheme 31

Coolant Heater Cord Replacement (LFW)

Cooling Fan Description and Operation

System Overview

The engine cooling fan system consists of 2 electric cooling fans and 3 fan relays. The cooling fan relays are arranged in a series/parallel (S/P) configuration. This allows the engine control module (ECM) to operate both fans together at low or high speeds using 2 fan control circuits. The cooling fans receive positive voltage from the cooling fan relays, which receive battery positive voltage from the underhood fuse block. The cooling fans are supplied a ground at G101 and G106.

Low Speed Operation

The ECM supplies a ground to the coil side of the cooling fan low speed relay. This energizes the coil and applies voltage directly to the left cooling fan through the switch side of the low speed relay. The left cooling fan is connected in series to the right cooling fan through the de-energized cooling fan-left high speed relay. The result is a series circuit that operates both fans at low speed.

High Speed Operation

The ECM supplies a ground to the coil side of the cooling fan low speed relay, the cooling fan-left high speed relay, and the cooling fan-right high speed relay. When energized, the right high speed fan relay applies voltage directly to the right cooling fan through the switch side of the relay. Simultaneously, the low speed fan relay and the cooling fan-left high speed relay provide ignition voltage and a direct path to ground for the left cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans operating at high speed.

When the request for fan operation is withdrawn, the fans may not turn OFF until the ignition switch is moved to the OFF position, or the vehicle speed exceeds approximately 10 mph. This is to prevent the fans from cycling ON and OFF excessively at idle.

Cooling System Description and Operation

Engine Coolant Indicators

1. The instrument panel cluster (IPC) shows the engine temperature on the temperature gauge. The value is sent on the data communication line from engine control module (ECM). When the coolant temperature is more than 128°C (262°F) IPC receives a discrete input from ECM requesting illumination.
2. The IPC performs the display test at the start of each ignition cycle. The IPC illuminates the TEMP indicator.

Coolant Level Control

The engine cooling system contains an engine coolant level switch to alert the driver in the event of a low coolant level. When the engine coolant level in the surge tank falls below a certain level, the coolant level switch opens. When the body control module (BCM) detects an open or a high voltage level on the coolant level indicator control circuit, for at least 10 seconds, it will send a GM LAN message to the driver information center (DIC) requesting display of the low coolant level message. There is approximately a 10-second delay before the BCM sends the GM LAN message to prevent the message from being displayed, due to coolant sloshing in the surge tank.

Coolant Heater

The optional engine coolant heater operates using AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather. The coolant heater helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. A weather shield on the cord is provided to protect the plug when not in use.

Cooling System

The cooling system's function is to maintain an efficient engine operating temperature during all engine speeds and operating conditions. The cooling system is designed to remove approximately one-third of the heat produced by the burning of the air-fuel mixture. When the engine is cold, the coolant does not flow to the radiator until the thermostat opens. This allows the engine to warm quickly.

Cooling Cycle

Coolant flows from the radiator outlet and into the water pump inlet. Some coolant flows from the water pump, to the heater core, then back to the water pump. This provides the passenger compartment with heat and defrost capability as the coolant warms up.

Coolant also flows from the water pump outlet and into the engine block. In the engine block, the coolant circulates through the water jackets surrounding the cylinders where the coolant absorbs heat.

The coolant then flows through the cylinder head gasket openings and into the cylinder heads. In the cylinder heads, the coolant flows through the water jackets surrounding the combustion chambers and valve seats, where the coolant absorbs additional heat.

Coolant is also directed to the throttle body. There the coolant circulates through passages in the casting. During initial start up, the coolant assists in warming the throttle body.

From the cylinder heads, the coolant flows to the thermostat. The flow of coolant will either be stopped at the thermostat until the engine reaches normal operating temperature, or the coolant will flow through the thermostat and into the radiator where the coolant is cooled. At this point, the coolant flow cycle is completed.

Efficient operation of the cooling system requires proper functioning of all cooling system components. The cooling system consists of the following components.

Coolant

The engine coolant is a solution made up of a 50/50 mixture of drinking water and anti-freeze. The coolant solution carries excess heat away from the engine to the radiator, where the heat is dissipated to the atmosphere.

Radiator

The radiator is a heat exchanger consisting of a core and 2 tanks. The aluminum core is a tube and fin crossflow design that extends from the inlet tank to the outlet tank. Fins are placed around the outside of the tubes to improve heat transfer to the atmosphere.

The inlet and outlet tanks are a molded, high temperature, nylon reinforced plastic material. A high temperature rubber gasket seals the tank flange edge to the aluminum core. The tanks are clamped to the core with clinch tabs. The tabs are part of the aluminum header at each end of the core.

The radiator also has a drain cock located in the bottom of the left hand tank. The drain cock unit includes the drain cock and drain cock seal.

Heat is removed from the coolant as the coolant passes through the radiator. The fins on the core transfer heat from the coolant passing through the tubes. Air passing between the fins absorbs the heat and cools the coolant.

Pressure Cap

The pressure cap seals and pressurizes the cooling system. The cap contains a blow off, or pressure valve and a vacuum, or an atmospheric valve

1. The pressure valve is held against the seat by a spring that protects the radiator by relieving pressure that exceeds 15 psi.
2. The vacuum valve is held against the seat by a spring that permits opening of the valve to relieve vacuum created when the cooling system cools. The vacuum, if not relieved, might cause the radiator to collapse.

The pressure cap allows the cooling system pressure to build up when the temperature increases. As the pressure builds, the boiling point of the coolant increases. Therefore, the engine coolant can be safely run at a temperature much higher than the boiling point of the coolant at atmospheric pressure. The hotter the coolant becomes, the faster the heat transfers from the radiator into the cooler air.

The pressure in the cooling system can get too high. When the pressure exceeds the strength of the spring, the pressure valve rises, venting the excess pressure.

As the engine cools, the temperature of the coolant drops and a vacuum is created in the cooling system. This vacuum causes the vacuum valve to open. This equalizes the pressure in the cooling system with the atmospheric pressure, preventing the radiator from collapsing.

Coolant Recovery System

The coolant recovery system consists of a plastic coolant recovery reservoir and overflow tube. The recovery reservoir is also called a recovery tank or expansion tank. This tank is partially filled with coolant and is connected to the radiator fill neck with the overflow tube. Coolant can flow back and forth between the radiator and the reservoir.

In effect, a cooling system with a coolant recovery reservoir is a closed system. When the pressure within the cooling system gets too high, the pressure valve in the pressure cap will open. This allows the coolant, which has expanded due to heat, to flow through the overflow tube and into the recovery reservoir. As the engine cools down, the temperature of the coolant drops and a vacuum is created in the cooling system. This vacuum opens the vacuum valve in the pressure cap, allowing some of the coolant in the reservoir to be siphoned back into the radiator. Under normal operating conditions, no coolant is lost. Although the coolant level in the recovery reservoir goes up and down, the radiator and cooling system are kept full. An advantage to using a coolant recovery reservoir is the elimination of almost all air bubbles from the cooling system. Coolant without bubbles absorbs heat much better than coolant with bubbles.

Air Baffles and Seals

The cooling system uses deflectors, air baffles and air seals to increase cooling system capability. Deflectors are installed under the vehicle to redirect airflow beneath the vehicle and through the radiator to increase engine cooling. Air baffles are also used to direct airflow through the radiator and increase cooling capability. Air seals prevent air from bypassing the radiator and A/C condenser, and prevent recirculation of hot air for better hot weather cooling and A/C condenser performance.

Water Pump

The water pump is a centrifugal vane impeller type pump. The pump consists of a housing with coolant inlet and outlet passages and an impeller. The impeller is a flat plate mounted on the pump shaft with a series of flat or curved blades or vanes. When the impeller rotates, the coolant between the vanes is thrown outward by centrifugal force. The impeller shaft is supported by one or more sealed bearings, which never need to be lubricated. With a sealed bearing, grease cannot leak out, and dirt and water cannot get in.

The water pump circulates coolant throughout the cooling system. The pump is driven by the crankshaft from the drive belt.

Thermostat

The thermostat is a coolant flow control component, whose purpose is to regulate the operating temperature of the engine. The thermostat utilizes a temperature sensitive wax-pellet element, which connects to a valve through a piston. Heating is causing the element to expand and exert pressure against a rubber diaphragm. This pressure forces the valve to open. Cooling causes the element to contract. This contraction allows a spring to push the valve closed.

When the coolant temperature is below 91°C (195°F), the thermostat valve remains closed. This prevents circulation of the coolant to the radiator and allows the engine to warm up quickly. After the coolant temperature reaches 91°C (195°F), the thermostat valve will open. The switch point will differ a little depending on engine. The coolant is then allowed to circulate through the thermostat to the radiator where the engine heat is dissipated to the atmosphere. The thermostat also provides a restriction in the cooling system, even after opening. This restriction creates a pressure difference which prevents cavitations at the water pump and forces coolant to circulate through the engine block.

For some engines a solenoid thermostat controlled by the ECM will open and close the circulation.

Transmission Oil Cooler

The transmission oil cooler is a heat exchanger and is located inside the right side end tank of the radiator. The transmission fluid temperature is regulated by the temperature of the engine coolant that surrounds the oil cooler as the transmission fluid passes through the cooler.

The transmission oil pump circulates the fluid through the feed line to the oil cooler. The fluid then flows through the cooler while the engine coolant absorbs heat from the fluid. The fluid is then pumped through the return line to the transmission.

Illustration Tool Number/ Description DT 47731 1/2 Inch Quick Connect Release Tool GE 47716 Vac N Fill Coolant Refill Tool EN 24460-A J 24460-01 Cooling System Pressure Tester GE 24731 J 24731 Tempil Stick GE 26568 J 26568 Coolant and Battery Fluid Tester BO 38185 J 38185 Hose Clamp Pliers GE 39400-A Halogen Leak Detector GE 42220 J 42220 Universal 12V Leak Detection Lamp GE 42401 A J 42401 Radiator Cap and Surge Tank Test Adapter EN 43651 J 43651 Water Pump Holding Tool

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See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• COMPONENT CONNECTOR END VIEWS - INDEX
• Electrical Center Identification Views
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Control Module References
• Diagnostic Repair Verification
• Relay Replacement (Within an Electrical Center)
• Engine Controls Schematics
• Instrument Cluster Description and Operation
• K20 Engine Control Module: Scan Tool Information
• Water Pump Cleaning and Inspection
• Coolant in Engine Oil
• Diagnostic Trouble Code (DTC) List - Vehicle
• Engine Coolant Temperature Sensor Replacement (LFW or LFX)
• Moving Parts and Hot Surfaces Warning
• Approximate Fluid Capacities
• Heater Core Replacement
• Engine Coolant/Water in Transmission
• Engine Will Not Crank - Crankshaft Will Not Rotate
• Coolant in Combustion Chamber
• Lower Engine Noise, Regardless of Engine Speed
• Lifting and Jacking the Vehicle
• Fastener Caution
• Intake Manifold Cover Replacement
• Engine Control Module Replacement
• Drive Motor Battery Coolant/Air Separator Replacement
• Front Bumper Fascia Replacement
• Exhaust Front Pipe Replacement (LFX)
• Intake Manifold Cover Replacement
• Power Steering Fluid Reservoir Replacement
• Heater Coolant Pump Hose Replacement
• Transmission Fluid Cooler Inlet Pipe Replacement
• Drivetrain and Front Suspension Frame Replacement
• DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LHU)
• Cooling Fan Description and Operation
• Thermostat Diagnosis
• Engine Overheating
• Cooling System Description and Operation
• Loss of Coolant
• Engine Coolant Fan Shroud Replacement
• Pressure Cap Testing
• Cooling System Leak Testing
• Adhesives, Fluids, Lubricants, and Sealers
• Flushing