Engine Cooling System Cadillac Escalade GMT900

Fastener Tightening Specifications

Scheme 1

Scheme 2

DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/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»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

Typical Scan Tool Data

FC Relay 1, and FC Relay 2 and 3 Ckt Open, Short Gnd, and Short Volts Test Status

Circuit/System Description

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 G100 and G101.

Conditions for Running the DTC

1. The system voltage is between 9-18 volts.
2. The engine speed is greater than 400 RPM.
3. DTCs P0480 and P0481 run continuously when the conditions above are met.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

DTCs P0480 and P0481 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0480 and P0481 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: Fan Relay 1 operates both fans at a low speed Fan Relay 2 and 3 operates one fan at high speed Fan Relays 1, 2, and 3 operates both fans at high speed

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

1. «Component Connector End Views»(/cadillac/escalade/gmt900-2006-2014/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index-a)
2. «Powertrain Component Views»(/cadillac/escalade/gmt900-2006-2014/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-powertrain-component-views)
3. «Electrical Center Identification Views»(/cadillac/escalade/gmt900-2006-2014/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-electrical-center-identification-views)

Description and Operation

Cooling Fan Description and Operation (Gas)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/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

Circuit/System Verification

1. Engine operating, observe the DTC information with a scan tool. DTC P0480 or P0481 should not be set.
2. Command the cooling fans ON and OFF at high speed while observing the scan tool circuit test status parameters listed below: FC Relay 1 Ckt Open, Short Gnd, and Short Volts Test Status FC Relay 2 and 3 Ckt Open, Short Gnd, and Short Volts Test Status The parameters should display OK or Not Run in each of the commanded states.
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 3 cooling fan relays listed below. FAN LO relay FAN CNTRL relay FAN HI relay
2. Ignition ON, verify that a test lamp illuminates between ground and the ignition circuit terminal 85 of each relay. If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.
3. Set the DMM on the diode setting. Connect the black lead to ground. Connect the red lead of the DMM to a control circuit terminal listed below: FAN LO Relay terminal 86 FAN CNTRL Relay terminal 86 FAN HI Relay terminal 86 The DMM should display OL. If less than the specified range, test the appropriate relay coil control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
4. Command the appropriate cooling fan relay ON and OFF with a scan tool. The DMM should transition from OL when commanded OFF to less than 1 V when commanded ON. If the circuit voltage does not correspond to the specified values, test the control circuit for an open/high resistance or for a short to voltage. If the circuit tests normal, replace the K20 ECM.
5. If all circuits test normal, test or replace the appropriate KR20 relay.

Component Testing

1. Ignition OFF, disconnect the KR20 cooling fan relay.
2. Test for 70-110 ohms between terminals 85 and 86. If not within the specified range, replace the KR20 cooling fan relay.
3. Measure the resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 The DMM should display OL. If less than the specified range, replace the KR20 cooling fan relay.
4. Test the KR20 Fan Control Relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the fan control relay.
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 the specified range, replace the KR20 cooling fan relay.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Attached to Wire Harness)»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) or «Relay Replacement (Within an Electrical Center)»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
2. «Underhood Electrical Center or Junction Block Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
3. «Engine Coolant Fan Replacement (Non-HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system)
4. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/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»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

FC Relay 1, 2 and 3 Ckt Open, Short Gnd, and Short Volts Test Status

The hybrid engine cooling fan system consists of two electrical cooling fans, two resistors, three engine control module (ECM) fan control circuits, and five fan relays. The relays are arranged in a series/parallel configuration that allows the ECM to operate the fans at low, medium, or high speed depending on cooling requirements. The ECM controls the five relays by grounding the relay control circuits.

To operate the fans, the ECM activates the applicable relay by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage. When the ECM is commanding a fan relay ON, the voltage of the control circuit should be low, near 0 volts. When the ECM is commanding a fan relay OFF, the voltage of the control circuit should be high, near battery voltage.

1. The ignition voltage is between 11-32 volts.
2. The engine speed is greater than 0 RPM.
3. DTC P0480, P0481, and P0482 run continuously when the conditions above are met.

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

DTCs P0480, P0481 and P0482 are Type B DTCs.

DTCs P0480, P0481 and P0482 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: Fan Relay 1 operates both fans at a low speed. Fan Relay 2 operates both fans at medium speed. Fan Relays 1, 2, and 3 operates both fans at high speed.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

1. «Component Connector End Views»(/cadillac/escalade/gmt900-2006-2014/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index-a)
2. «Powertrain Component Views»(/cadillac/escalade/gmt900-2006-2014/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-powertrain-component-views)
3. «Electrical Center Identification Views»(/cadillac/escalade/gmt900-2006-2014/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-electrical-center-identification-views)

Description and Operation

Cooling Fan Description and Operation (Gas)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/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

1. Engine operating, observe the DTC information with a scan tool. DTC P0480, P0481, or P0482 should not be set.
2. Command the cooling fans ON and OFF at high speed while observing the scan tool circuit test status parameters listed below: FC Relay 1 Ckt Open, Short Gnd, and Short Volts Test Status FC Relay 2 Ckt Open, Short Gnd, and Short Volts Test Status FC Relay 3 Ckt Open, Short Gnd, and Short Volts Test Status The parameters should display OK or Not Run in each of the commanded states.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Ignition OFF, open the hood to disable the Auto-Stop function.
2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «DTC P254F»(/cadillac/escalade/gmt900-2006-2014/remont/door-locks-anti-theft-systems/#immobilizer-system) .
3. Ignition OFF, disconnect all 5 cooling fan relays.
4. Ignition ON, verify that a test lamp illuminates between ground and the ignition circuit terminal of each relay listed below: FAN LO Relay terminal 85 FAN MID 1 Relay terminal 85 FAN CNTRL Relay terminal 86 FAN MID 2 Relay terminal 86 FAN HI Relay terminal 86 If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test all the components connected to the ignition voltage circuit and replace as necessary.
5. Set the DMM on the diode setting. Connect the black lead to ground. Connect the red lead of the DMM to a control circuit terminal listed below: FAN LO Relay terminal 86 FAN MID 1 Relay terminal 86 FAN CNTRL Relay terminal 85 FAN MID 2 Relay terminal 85 FAN HI Relay terminal 85 The DMM should display OL. If less than the specified range, test the appropriate relay coil control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
6. Command the appropriate cooling fan relay ON and OFF with a scan tool. The DMM should transition from OL when commanded OFF to less than 1 V when commanded ON. If the circuit voltage does not correspond to the specified values, test the control circuit for an open/high resistance or for a short to voltage. If the circuit tests normal, replace the K20 ECM.
7. If all circuits test normal, test or replace the appropriate KR20 relay.

1. Ignition OFF, disconnect the KR20 cooling fan relay.
2. Test for 50-90 ohms between terminals 85 and 86. If not within the specified range, replace the KR20 cooling fan relay.
3. Measure the resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 The DMM should display OL. If less than the specified range, replace the KR20 cooling fan relay.
4. Test the KR20E Fan Control Relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the KR20E cooling fan relay.
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 the specified range, replace the KR20 cooling fan relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Attached to Wire Harness)»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) or «Relay Replacement (Within an Electrical Center)»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
2. «Underhood Electrical Center or Junction Block Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
3. «Engine Coolant Fan Replacement (HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system)
4. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/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»(/cadillac/escalade/gmt900-2006-2014/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 (ECT) sensor to monitor the engine for an over-termperature condition. This condition occurs when the coolant temperature is above a calibrated value for a calibrated length of time. The ECM will disable half of the cylinders by turning OFF the fuel injectors. By disabling half of cylinders, the ECM is able to reduce the temperature of the coolant.

The engine is operating.

All V8

The coolant temperature is warmer than 129°C (264°F) for greater than 10 seconds.

6.0L-Hybrid

The coolant temperature is warmer than 132°C (270°F) for greater than 10 seconds.

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

Conditions for Clearing the DTC

DTC P1258 is a Type A DTC.

Description and Operation

1. «Cooling System Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Instrument Cluster Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges)
3. «Indicator/Warning Message Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges)
4. «Audible Warnings Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges__audible-warnings-description-and-operation)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Note. If DTC P0480, P0481, or P0482 is set, diagnose that DTC first.

1. Observe the engine coolant level. The engine coolant level should be within operating range. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static)
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)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static)
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 The radiator and A/C condenser for any air flow obstructions or bent fins-Refer to «Symptoms - Engine Cooling»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Command the cooling fans ON in each available speed with a scan tool. If the cooling fans are inoperative in any of the commanded states, refer to «Cooling Fan Inoperative (without HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling Fan Inoperative (with HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Test the thermostat for correct operation. Refer to «Thermostat Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Test the engine cooling system for overheating. Refer to «Engine Overheating»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__engine-overheating) .
3. Inspect the water pump and coolant flow for correct operation. Refer to «Water Pump Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Inspect the engine for worn/leaking/cracked cylinder heads and engine block. Refer to «Coolant in Combustion Chamber»(/cadillac/escalade/gmt900-2006-2014/remont/mechanical/#engine-mechanical-53l-60l-62l-diagnostic-information-and-procedures__coolant-in-combustion-chamber) and «Coolant in Engine Oil»(/cadillac/escalade/gmt900-2006-2014/remont/mechanical/#engine-mechanical-53l-60l-62l-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»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) and verify all of the following items: Ensure that the engine control module (ECM) and indicator lamp are operating correctly. Ensure that there are no diagnostic trouble codes (DTCs) that are stored. Scan tool data is within a normal operating range. Refer to «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for scan tool information.
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 system operation in order to familiarize yourself with the system functions. Refer to Cooling Fan Description and Operation (Gas) .

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 areas

1. Ensure that the control module grounds are clean, tight, and correctly located.
2. Inspect cooling system hoses and pipes for splits, kinks, and proper connections. Inspect thoroughly for any type of a leak or a restriction.
3. Inspect for a dirty or restricted radiator and 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 surge tank reservoir for the 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 determine an intermittent condition

1. Moisture and water intrusion in connectors, terminals, and components
2. 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 is located too tight, or chaffed circuits
6. High or low ambient temperature
7. High or low engine coolant temperatures
8. High underhood temperatures
9. Heat build up in component or circuit 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, and after factory add on accessories

If an intermittent is determined, 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 (without HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling Fan Always On (with HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Cooling Fan Inoperative (without HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) or «Cooling Fan Inoperative (with HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system)
3. «Engine Overheating»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__engine-overheating)
4. «Loss of Coolant»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant)
5. «Thermostat Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system)
6. «Coolant Heater Inoperative»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system)
7. «Engine Fails To Reach Normal Operating Temperature»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__engine-fails-to-reach-normal-operating)

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/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»(/cadillac/escalade/gmt900-2006-2014/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 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 G100 and G101.

The ECM has the capability of providing command to the fan relays even while 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.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation (Gas)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

1. Verify that the following DTCs are not set: P0480 or P0481. If a DTC is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
2. Ignition ON, verify with a scan tool that the control module is not commanding fan activation.
3. Ignition ON, observe that the fans are not activated.

1. Ignition OFF, disconnect each cooling fan relay one at a time.
2. Ignition ON, observe that the fans are not activated. If the fans are activated, test for a short to voltage in the relay controlled output circuit. If the fans are not activated, test or replace the appropriate cooling fan relay.

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 70-110 ohms between terminals 85 and 86. If not within the specified range, replace the cooling fan relay.
3. Measure the resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 The DMM should display OL. If less than the specified range, replace the cooling fan relay.
4. Test the Fan Control Relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the cooling fan relay.
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 the specified range, replace the cooling fan relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Attached to Wire Harness)»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) or «Relay Replacement (Within an Electrical Center)»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
2. «Underhood Electrical Center or Junction Block Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/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»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The hybrid engine cooling fan system consists of two electrical cooling fans, two resistors, three engine control module (ECM) fan output control drivers, and five fan relays. The relays are arranged in a series/parallel configuration that allows the ECM to operate the fans at low, medium, or high speed depending on engine cooling requirements. The ECM controls the five relays by grounding the relay control circuits.

The ECM has the capability of providing command to the fan relays even while 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.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation (Gas)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/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. Verify that the following DTCs are not set: P0480, P0481, P0482. If a DTC is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
2. Verify with a scan tool that the ECM is not commanding fan relay activation.
3. Ignition ON, observe that the fans are not activated.

1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation__hybrid-modes-of-operation-description) .
2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P254F.
3. Ignition OFF, disconnect each cooling fan relay one at a time.
4. Ignition ON, observe that the fans are not activated. If the fans are activated, test for a short to voltage in the relay controlled output circuit. If the fans are not activated, test or replace the appropriate cooling fan relay.

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 50-90 ohms between terminals 85 and 86. If not within the specified range, replace the cooling fan relay.
3. Measure the resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 The DMM should display OL. If less than the specified range, replace the cooling fan relay.
4. Test the Fan Control Relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the cooling fan relay.
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 the specified range, replace the cooling fan relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Attached to Wire Harness)»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) or «Relay Replacement (Within an Electrical Center)»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
2. «Underhood Electrical Center or Junction Block Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/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»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Fan Low Relay

Fan Control Relay

Fan High Relay

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 G100 and G101.

1. The ECM has the capability of providing command to the fan relays even while 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: Fan Relay 1 operates both fans at a low speed Fan Relay 2 and 3 operates one fan at high speed Fan Relay 1, 2, and 3 operates both fans at high speed

Schematic Reference

Engine Cooling Schematics

Description and Operation

Cooling Fan Description and Operation (Gas)

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/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 DTC P0480 or P0481 is not set. If a DTC is set, refer to «DTC P0480 or P0481 (without HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Ignition ON, command high and low speed fans ON and OFF with a scan tool. Verify that both fans turn ON and OFF when changing between the commanded states.

Note. You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, disconnect the cooling fan relays.
2. Connect a 30 A fused jumper between the Fan Control relay switch circuit terminal 30 and the relay ground circuit terminal 87. This will complete the left side fan ground circuit. Leave this jumper in place for the remainder of this procedure.
3. Ignition ON, verify that a test lamp illuminates between ground and the relay switched ignition circuit terminal listed below: Fan Low Relay terminal 30 Fan High Relay terminal 30 If the test lamp does not illuminate, test the appropriate relay switch B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay switch B+ circuit fuse is open, test the relay controlled output circuit for a short to ground. If the circuit tests normal, test or replace the appropriate G10 cooling fan.
4. Connect a 30 A fused jumper between the cooling fan relay circuit terminals listed below: Fan High Relay terminals 87 and 30 Fan Low Relay terminals 87 and 30 Verify the appropriate fan is activated. If the corresponding cooling fan does not activate, test the relay controlled output circuit and the cooling fan ground circuit for an open/high resistance. If the circuits tests normal, test or replace the appropriate G10 cooling fan. If the corresponding cooling fan activates, replace the appropriate cooling fan relay.
5. Install the Fan Control Relay. Verify both fans activate at low speed. If both fans do not activate, test the Fan Control Relay switched output circuit terminal 87A for a short to ground or an open/high resistance.
6. If all the circuits test normal, test or replace the Fan Control Relay.

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 70-110 ohms between terminals 85 and 86. If not within the specified range, replace the cooling fan relay.
3. Measure the resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 The DMM should display OL. If less than the specified range, replace the cooling fan relay.
4. Test the Fan Control Relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the cooling fan relay.
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 the specified range, replace the cooling fan relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Engine Coolant Fan Motor Replacement (Non-HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Relay Replacement (Attached to Wire Harness)»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) or «Relay Replacement (Within an Electrical Center)»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
3. «Underhood Electrical Center or Junction Block Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/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»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The hybrid engine cooling fan system consists of two electrical cooling fans, two resistors, three engine control module (ECM) fan output control drivers, and five fan relays. The relays are arranged in a series/parallel configuration that allows the ECM to operate the fans at low, medium, or high speed depending on engine cooling requirements. The ECM controls the five relays by grounding the relay control circuits.

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: Fan Relay 1 operates both fans at a low speed Fan Relay 2 operates both fans at medium speed Fan Relays 1, 2, and 3 operates both fans at high speed

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation (Gas)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/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, observe the DTC information with a scan tool. Verify that DTC P0480 or P0481 is not set. If a DTC is set, refer to «DTC P0480, P0481, or P0482 (with HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Ignition ON, command the cooling fans ON and OFF at high, medium, and low speed with a scan tool. Verify that both fans turn ON and OFF when changing between the commanded states.

Note. You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation__hybrid-modes-of-operation-description) .
2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P254F.
3. Ignition OFF, disconnect the cooling fan relays.
4. Ignition ON, verify that a test lamp illuminates between the Fan Control relay ground circuit terminal 87 and B+. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
5. Connect a 30 A fused jumper between the Fan Control relay switch circuit terminal 30 and the relay ground circuit terminal 87. This will complete the left side fan ground circuit. Leave this jumper in place for the remainder of this procedure.
6. Ignition ON, verify that a test lamp illuminates between ground and the relay switched ignition circuit terminal listed below: Fan Low Relay terminal 87 Fan Mid 1 Relay terminal 87 Fan Mid 2 Relay terminal 30 Fan High Relay terminal 30 If the test lamp does not illuminate, test the appropriate relay switch B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay switch B+ circuit fuse is open, test the relay controlled output circuit for a short to ground. If the circuit tests normal, test or replace the appropriate G10 cooling fan.
7. Connect a 30 A fused jumper between the cooling fan relay circuit terminals listed below: Fan High Relay terminals 87 and 30 Fan Low Relay terminals 87 and 30 Verify the appropriate fan is activated. If the corresponding cooling fan does not activate, test the relay controlled output circuit and the cooling fan ground circuit for an open/high resistance. If the circuits tests normal, test or replace the appropriate G10 cooling fan.
8. Connect a 30 A fused jumper between the cooling fan relay circuit terminals listed below: Fan Mid 1 Relay terminal 87 and 30 Fan Mid 2 Relay terminal 30 and 87 The appropriate fan should activate and operate at a reduced speed. If the corresponding cooling fan does not activate, test the relay controlled output circuit for an open/high resistance. If the circuit tests normal, test or replace the appropriate R10 cooling fan resistor. If the corresponding cooling fan activates, replace the appropriate cooling fan relay.
9. Ignition OFF, install the Fan Control relay.
10. Ignition ON, connect a 30 A fused jumper wire between the Fan Low relay terminals 87 and 30. Both cooling fans should activate and operate at a low speed. If both fans do not activate, test the Fan Control Relay switched output circuit terminal 87A for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the Fan Control relay.
11. If all the circuits test normal, test or replace the appropriate cooling fan relay.

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 50-90 ohms between terminals 85 and 86. If not within the specified range, replace the cooling fan relay.
3. Measure the resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 The DMM should display OL. If less than the specified range, replace the cooling fan relay.
4. Test the Fan Control Relay for less than 2 ohms between terminals 30 and 87A. If greater than the specified range, replace the cooling fan relay.
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 the specified range, replace the cooling fan relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Attached to Wire Harness)»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) or «Relay Replacement (Within an Electrical Center)»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
2. «Underhood Electrical Center or Junction Block Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
3. «Engine Coolant Fan Motor Replacement (HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system)
4. «Engine Coolant Fan Resistor Replacement (Right HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) or «Engine Coolant Fan Resistor Replacement (Left HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system)

Engine Overheating

Loss of Coolant

Tools Required

J 24731: Tempil Stick

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. Temperature sticks can be used to determine a thermostat's operating range, by rubbing 87°C (188°F) and 97°C (206°F) sticks on the thermostat housing.

1. Use a J 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. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/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»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The optional coolant heater is a heating element that mounts in the engine block in place of an existing anti-freeze plug. The coolant heater operates using an external 110 volt AC power source and is designed to warm the coolant in the engine block for improved starting in very cold weather. The coolant heater also helps reduce fuel consumption when a cold engine is warming up. The detachable AC power cord contains an internal thermal switch that opens, to prevent operation when the ambient temperature is warmer than -10°C (14°F), and closes at -18°C (0°F) to allow operation. The power cord is also equipped with a weather shield to protect the plug when not in use.

Electrical Information Reference

1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Note. The power supply cord will test open due to an internal thermal switch if the ambient temperature is warmer than -10°C (14°F). The thermal switch is designed to close when the ambient temperature is below -18°C (0°F).

1. Test the engine coolant heater for an open or short to ground. If open or shorted, replace the heater.
2. If the heater tests normal, replace the coolant heater power cord.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Coolant Heater Replacement (With LC9, L76,or L92)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (With LY2, LMG, LY5, LY6 or LFA)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Coolant Heater Cord Replacement (With LY2, LY5 or LMG)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Cord Replacement (With LC9, LY6, L92 or LFA)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Cord Replacement (With LY6)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system)

Engine Fails To Reach Normal Operating Temperature

Pressure Cap Testing

Special Tools

1. J 42401 Radiator Cap/Surge Tank Test Adapter. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
2. J 24460-01 Cooling System Pressure Tester. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the pressure cap.
2. Wash the pressure cap sealing surface with water.
3. Use the J 24460-01 (1) with J 42401 (2) in order to test the pressure cap. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Test the pressure cap for the following conditions: Pressure release when the J 24460-01 exceeds the pressure rating of the pressure cap. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) . 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.

Cooling System Leak Testing

Special Tools

1. J 24460-01 Cooling System Pressure Tester. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
2. J 42401 Radiator Cap/ Surge Tank Test Adapter. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the pressure cap.
2. Test the operation of the pressure cap. Refer to «Pressure Cap Testing»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__pressure-cap-testing) .
3. Wash the pressure cap mating surface with water.
4. Use the J 24460-01 with the J 42401 in order to apply pressure to the cooling system. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-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.

Cooling System Draining and Filling (Static Fill)

Special Tools

1. J 26568 Coolant and Battery Tester. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
2. J 38185 Hose Clamp Pliers. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .

Draining Procedure

1. Follow the steps below in order to remove the surge tank fill cap: Slowly rotate the cap counterclockwise. Stop rotating and allow the hissing to stop. After all the hissing stops, continue turning counterclockwise in order to remove the cap.
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
3. Place a drain pan under the lower radiator hose and/or drain cock.
4. Using the J 38185 , reposition the lower radiator hose clamp. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Reposition the lower radiator hose and/or drain cock from the radiator.
6. Drain the cooling system.
7. If a complete engine block drain is required, remove the left and right engine block coolant drain plugs.
8. Remove the engine block coolant heater, if equipped. Refer to «Coolant Heater Replacement (With LC9, L76,or L92)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (With LY2, LMG, LY5, LY6 or LFA)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
9. Inspect the coolant.
10. 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»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__flushing) .

Filling Procedure

1. Install the lower radiator hose and/or drain cock to the radiator.
2. Using the J 38185 , reposition the lower radiator hose clamp. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
3. If the left and right engine block coolant drain plugs were removed, perform the following: Apply pipe sealer to the drain plugs. Install the drain plugs. Tighten: Tighten the drain plugs to 60 N.m (44 lb ft).
4. Install the engine block coolant heater, if equipped. Refer to «Coolant Heater Replacement (With LC9, L76,or L92)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) or «Coolant Heater Replacement (With LY2, LMG, LY5, LY6 or LFA)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
5. Lower the vehicle.
6. Slowly fill the cooling system with a 50/50 coolant mixture. Refer to «Approximate Fluid Capacities»(/cadillac/escalade/gmt900-2006-2014/remont/lubrication-system/#maintenance-and-lubrication__approximate-fluid-capacities) .
7. Install the coolant pressure cap.
8. Start the engine.
9. Run the engine at 2,000-2,500 RPM until the engine reaches normal operating temperature. Engine should reach an operating temperature of 90°C (194°F) and the upper radiator hose should be HOT.
10. Allow the engine to idle for 3 minutes.
11. Shut the engine OFF.
12. Allow the engine to cool.
13. Top off the coolant as necessary.
14. Inspect the concentration of the engine coolant using the J 26568 . See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
15. Rinse away any excess coolant from the engine and the engine compartment.

Flushing

Radiator Cleaning

1. Some conditions may require the use of warm water and a mild detergent.
2. Clean the A/C condenser fins.
3. Clean between the A/C condenser and radiator.
4. Clean the radiator cooling fins.
5. Straighten any damaged cooling fins.

Scheme 3

Scheme 4

Scheme 5

Removal Procedure

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .
2. Reposition the surge tank inlet hose clamp from the radiator.
3. Remove the surge tank inlet hose from the radiator.
4. Reposition the surge tank inlet hose clamp at the surge tank.
5. Remove the surge tank inlet hose (1) from the surge tank.

Installation Procedure

1. Install the surge tank inlet hose (1) to the surge tank.
2. Position the surge tank inlet hose clamp to the surge tank.
3. Install the surge tank inlet hose to the radiator.
4. Position the surge tank inlet hose clamp to the radiator.
5. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .

Scheme 6

Special Tools

J 43181 Heater Line Quick Connect Release Tool

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .
2. Loosen the air cleaner outlet duct clamps at the following locations: Throttle body Mass airflow/intake air temperature (MAF/IAT) sensor
3. Remove the air cleaner outlet duct.
4. If equipped without regular production option (RPO) C36 auxiliary heater, remove the surge tank/heater outlet hose (1) from the mounting clip.
5. If equipped with RPO C36 auxiliary heater, remove the surge tank/heater outlet hose (1) from the mounting clip.
6. Install the J 43181 to the surge tank outlet hose (black connector).
7. Close the J 43181 around the surge tank outlet hose.
8. Firmly pull the J 43181 into the quick connect end of the outlet hose.
9. If equipped without RPO C36 auxiliary heater, firmly grasp the outlet hose. Pull the outlet hose in order to disengage the hose from the heater and blower module.
10. If equipped with RPO C36 auxiliary heater, firmly grasp the outlet hose. Pull the outlet hose in order to disengage the hose from the heater and blower module.
11. Reposition the surge tank outlet hose clamp at the surge tank.
12. Remove the surge tank outlet hose (2) from the surge tank.
13. Reposition the surge tank outlet hose clamp at the water pump.
14. Remove the surge tank outlet hose from the water pump.
15. Remove the surge tank outlet hose.

1. Install the surge tank outlet hose.
2. Install the surge tank outlet hose to the water pump.
3. Position the surge tank outlet hose clamp to the water pump.
4. Install the surge tank outlet hose (2) to the surge tank.
5. Position the surge tank outlet hose clamp to the surge tank.
6. If equipped with RPO C36 auxiliary heater, connect the surge tank outlet hose to the heater and blower module.
7. If equipped without RPO C36 auxiliary heater, connect the surge tank outlet hose to the heater and blower module. Firmly push the hose onto the heater and blower module pipe until an audible click is heard.
8. If equipped with RPO C36 auxiliary heater, install the surge tank/heater outlet hose (1) to the mounting clip.
9. If equipped without RPO C36 auxiliary heater, install the surge tank/heater outlet hose (1) to the mounting clip.
10. Install the air cleaner outlet duct.
11. Align the arrow at the throttle body end of the duct with the throttle body attaching stud.
12. Tighten the air cleaner outlet duct clamps at the following locations: Throttle body MAF/IAT sensor Tighten: Tighten the clamps to 7 N.m (62 lb in).
13. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .

Scheme 7

Scheme 8

Scheme 9

Scheme 10

Scheme 11

Scheme 12

Scheme 13

Engine Oil Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection

Special Tools

1. DT-47731 1/2 in Line Quick Release Tool
2. J 28585 Universal Snap Ring Remover for the 5/8 in Line

1. Remove the plastic caps from the quick connect fittings by pulling the caps back along the pipe before installation.
2. Install the DT-47731 onto the engine oil cooler (EOC) pipe, or use the J 28585
3. Slide the DT-47731 toward the EOC pipe fitting, or use the J 28585
4. Connect the DT-47731 onto the EOC pipe fitting.
5. Rotate the DT-47731 or use the J 28585 until the retainer clip (1) rises above the fitting retainer seat.
6. Pull back on the EOC pipe to disengage the pipe from the EOC pipe fitting.
7. Remove the DT-47731 or the J 28585 from the EOC pipe.

1. Install the EOC pipe into the EOC pipe fitting. A distinct snap should be heard or felt when assembling the EOC pipe to the fitting.
2. To ensure the cooler line is properly installed, give the cooler pipe a gentle pull.

The optional oil cooler is either an integral part of the radiator or a separate unit placed in front of the radiator. The cooler lines and hoses are serviceable.

1. Disconnect the engine oil cooler quick connect fittings. Refer to «Engine Oil Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__engine-oil-cooler-hosepipe-quick-connect-fitting) .
2. If equipped with regular production option (RPO) L76 (6.0L) engine, perform the following. Open the oil cooler hose clip located on the lower fan shroud. Remove the oil cooler hoses from the clip.
3. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
4. If equipped with RPO LY6 (6.0L) engine, remove the oil cooler hoses from the clip.
5. Place a jack or utility stands at the rear of the vehicle.
6. If equipped, remove the engine protection shield. Refer to «Engine Shield Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/frames-subframes-crossmembers/#frame-and-underbody) .
7. If equipped, remove the front differential carrier shield. Refer to «Shield Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/differentials-drive-axles/#front-drive-axle) .
8. For both 1500 and 2500 series, support the front differential carrier with a suitable adjustable jack.
9. For 1500 series vehicles, remove the differential carrier right side nuts.
10. Remove the differential carrier left side bolts.
11. Lower the differential carrier.
12. For 2500 series vehicles, remove the differential carrier right side nuts.
13. Remove the differential carrier upper mounting bolt and nut.
14. Remove the differential carrier lower mounting bolt and nut.
15. If equipped with RPO L76 (6.0L) engine, perform the following: Lower the differential carrier. Remove the oil cooler hose adapter bolts (2). Remove the oil cooler hose assembly and gasket. Discard the gasket. Inspect the fittings, connectors, and cooler hoses for damage or distortion.
16. If equipped with RPO LY6 (6.0L) engine, perform the following: Remove the oil cooler hose bracket bolt. (1) Remove the oil cooler hose adapter bolts. (2) Remove the oil cooler hose assembly. Discard the gasket. Inspect the fittings, connectors, and cooler hoses for damage or distortion.

1. If equipped with RPO LY6 (6.0L) engine, perform the following: Install the oil cooler hose assembly and a NEW gasket. Install the oil cooler hose adapter bolts (2). Tighten: Tighten the bolts to 12 N.m (106 lb in). Install the oil cooler hose bracket bolt. Tighten: Tighten the bolt to 25 N.m (18 lb ft).
2. If equipped with a RPO L76 (6.0L) engine, perform the following. Install the oil cooler hose assembly and a NEW gasket. Install the oil cooler hose adapter bolts (2). Tighten: Tighten the bolts to 12 N.m (106 lb in). Install the oil cooler hose bracket bolt (1). Tighten: Tighten the bolt to 25 N.m (18 lb ft).
3. For 2500 series vehicles, raise the differential carrier into position.
4. Install the differential carrier left side upper bolt and nut until snug.
5. Install the differential carrier left side lower bolt and nut until snug.
6. Install the differential carrier right side nuts. Tighten: Tighten the bolt to 100 N.m (74 lb ft).
7. For 1500 series vehicles, raise the differential carrier into position.
8. Install the differential carrier right side nuts.
9. Install the differential carrier left side bolts. Tighten: Tighten the bolts/nuts to 100 N.m (74 lb ft).
10. If equipped, install the engine protection shield. Refer to «Engine Shield Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/frames-subframes-crossmembers/#frame-and-underbody) .
11. Remove the jack or utility stand from the rear of the vehicle.
12. Lower the vehicle.
13. If equipped with RPO LY6 (6.0L) engine, install the oil cooler hoses to the clip.
14. If equipped with RPO L76 (6.0L) engine, perform the following: Install the oil cooler hoses to the hose clip on the fan shroud. Snap the oil cooler hose clip shut.
15. Install the oil cooler lines to the radiator. Refer to «Engine Oil Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__engine-oil-cooler-hosepipe-quick-connect-fitting) .

Fan Replacement (Mechanical)

Special Tools

1. J 41240-5A Fan Clutch Wrench. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
2. J-48460 Fan Clutch Remover and Installer Kit. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Remove the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (Mechanical)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Install the J-48460 Fan Clutch Remover and Installer Kit (1). See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
3. Install the J 41240-5A Fan Clutch Wrench (2). See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
4. Remove the fan hub nut from the water pump in a counterclockwise rotation.
5. Remove the fan clutch bolts from the rear of the fan blade.
6. Separate the fan clutch from the fan blade.

1. Install the fan clutch onto the fan blade.
2. Install the fan clutch bolts. Tighten: Tighten the bolts to 23 N.m (17 lb ft).
3. Install the fan assembly.
4. Install the J-48460 Fan Clutch Remover and Installer Kit (1) and J 41240-5A Fan Clutch wrench (2). See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) . Tighten: Tighten the nut clockwise to 56 N.m (41 lb ft).
5. Install the upper fan shroud. Refer to «Engine Coolant Fan Upper Shroud Replacement (Mechanical)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 14

1. Remove the cooling fan and shroud. Refer to «Cooling Fan and Shroud Replacement (Non-HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the cooling fan blade retainers.
3. Remove the cooling fan blades.

Note. The electric cooling fan assembly uses a 5-blade fan and a 7-blade fan. It does not matter which side the fan blades are installed on. DO NOT install two 5-blade assemblies or two 7-blade assemblies, as this would cause a noise issue.

1. Install the cooling fan blades.
2. Install the cooling fan blade retainers.
3. Install the cooling fan and shroud. Refer to «Cooling Fan and Shroud Replacement (Non-HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 15

1. Remove the cooling blade(s). Refer to «Engine Coolant Fan Replacement (Non-HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the cooling fan motor bolts.
3. Remove the cooling fan motor(s).

1. Install the cooling fan motor(s).
2. Install the cooling fan motor bolts. Tighten: Tighten the bolts to 10 N.m (89 lb in).
3. Install the cooling fan blades. Refer to «Engine Coolant Fan Replacement (Non-HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static)
2. Remove air inlet duct.
3. Disconnect upper radiator hose from radiator.
4. Disengage the radiator inlet hose clip (2) at the fan shroud.
5. If necessary, reposition the surge tank inlet hose clamp at the radiator.
6. If necessary, remove the surge tank inlet hose from the radiator.
7. Disconnect the electrical connectors from the cooling fans.
8. Remove the clip attaching the wiring harness to the shroud.
9. Remove transmission cooler lines bolts from fan shroud.
10. If necessary, open the engine oil cooler line clip and remove the cooler lines from the clip.
11. Remove the cooling fan shroud bolts.
12. Remove the cooling fan and shroud.

1. Install the cooling fan and shroud.
2. Install the cooling fan shroud bolts. Tighten: Tighten the bolts to 9 N.m (80 lb in).
3. If equipped, install the cooler lines to the clip and close the clip.
4. Connect the electrical connectors to the cooling fans.
5. Install the clip attaching the wiring harness to the shroud.
6. Install the transmission cooling line bolts to fan shroud. Tighten: Tighten the bolts to 4 N.m (35 lb in).
7. If necessary, install the surge tank inlet hose to the radiator.
8. If necessary, reposition the surge tank inlet hose clamp at the radiator.
9. Engage the radiator inlet hose clip (2) at the fan shroud.
10. Connect upper radiator hose from radiator.
11. Install air inlet duct.
12. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static)

Scheme 16

Scheme 17

Scheme 18

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .
2. Remove the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-repair-instructions) .
3. Reposition the radiator outlet hose clamp at the water pump inlet.
4. Remove the radiator outlet hose from the water pump inlet.
5. Remove the water pump inlet bolts (1).
6. Remove the water pump inlet from the water pump.
7. Remove and discard the water pump inlet seal.

1. Install a NEW water pump inlet seal to the water pump inlet.
2. Position the water pump inlet to the water pump.
3. Install the water pump inlet bolts (1) and tighten to 15 N.m (11 lb ft).
4. Install the radiator outlet hose to the water pump inlet.
5. Position the radiator outlet hose clamp at the water pump inlet.
6. Install the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-repair-instructions) .
7. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .

1. Remove the thermostat housing. Refer to «Engine Coolant Thermostat Housing Replacement (LFA,LH6, LMG,LY2, LY5,LY6)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the thermostat.

1. Install the thermostat.
2. Install the thermostat housing. Refer to «Engine Coolant Thermostat Housing Replacement (LFA,LH6, LMG,LY2, LY5,LY6)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .

1. If replacing the rear coolant air bleed covers, remove the intake manifold. Refer to «Intake Manifold Replacement (Without AFM)»(/cadillac/escalade/gmt900-2006-2014/remont/mechanical/#engine-mechanical-53l-60l-62l-repair-instructions-on-vehicle) . Otherwise proceed to the next step.
2. Remove the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-repair-instructions) .
3. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .
4. Reposition the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
5. Remove the radiator vent inlet hose (2) from the coolant air bleed pipe fitting.
6. Remove the coolant air bleed pipe bolts (309) (intake manifold shown removed for clarity).
7. Remove the coolant air bleed pipe (307) and seals (308).
8. Remove the coolant air bleed cover bolts (312), if required.
9. Remove the coolant air bleed covers (313) and seals (308), if required.
10. Remove the seals (308) from the coolant air bleed pipe and/or covers.
11. Discard the seals.

1. Install the seals onto the coolant air bleed pipe and/or covers.
2. Install the coolant air bleed pipe (307) and seals (308) onto the cylinder heads.
3. Install the coolant air bleed pipe bolts (309) and tighten to 12 N.m (106 lb in).
4. Install the coolant air bleed covers (313) and seals (308), if required.
5. If required, install the coolant air bleed cover bolts (312) and tighten to 12 N.m (106 lb in).
6. Install the radiator vent inlet hose (2) to the coolant air bleed pipe fitting.
7. Position the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
8. Install the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-repair-instructions) .
9. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .
10. If the rear coolant air bleed covers were replaced, install the intake manifold. Refer to «Intake Manifold Replacement (With AFM)»(/cadillac/escalade/gmt900-2006-2014/remont/mechanical/#engine-mechanical-53l-60l-62l-repair-instructions-on-vehicle) .

1. If replacing the rear coolant air bleed covers, remove the intake manifold. Refer to «Intake Manifold Replacement (With AFM)»(/cadillac/escalade/gmt900-2006-2014/remont/mechanical/#engine-mechanical-53l-60l-62l-repair-instructions-on-vehicle) . Otherwise proceed to the next step.
2. Remove the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-repair-instructions) .
3. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .
4. Reposition the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
5. Remove the radiator vent inlet hose (2) from the coolant air bleed pipe fitting.
6. Remove the coolant air bleed pipe bolts (309) (intake manifold shown removed for clarity).
7. Remove the coolant air bleed pipe (307) and seals (308).
8. Remove the coolant air bleed cover bolts (312), if required.
9. Remove the coolant air bleed covers (313) and seals (308), if required.
10. Remove the seals (308) from the coolant air bleed pipe and/or covers.
11. Discard the seals.

1. Install the seals onto the coolant air bleed pipe and/or covers.
2. Install the coolant air bleed pipe (307) and seals (308) onto the cylinder heads.
3. Install the coolant air bleed pipe bolts (309) and tighten to 12 N.m (106 lb in).
4. Install the coolant air bleed covers (313) and seals (308), if required.
5. If required, install the coolant air bleed cover bolts (312) 12 N.m (106 lb in).
6. Install the radiator vent inlet hose (2) to the coolant air bleed pipe fitting.
7. Position the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
8. Install the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-repair-instructions) .
9. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .
10. If the rear coolant air bleed covers were replaced, install the intake manifold. Refer to «Intake Manifold Replacement (With AFM)»(/cadillac/escalade/gmt900-2006-2014/remont/mechanical/#engine-mechanical-53l-60l-62l-repair-instructions-on-vehicle) .

1. If necessary, remove the engine sight shield. Refer to «Upper Intake Manifold Sight Shield Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/mechanical/#engine-mechanical-53l-60l-62l-repair-instructions-on-vehicle) for the 4.8L, 5.3L, and 6.0L engines.
2. Position the coolant air bleed hose clamp at the throttle body.
3. Remove the coolant air bleed hose from the throttle body.
4. Position the hose clamp at the pipe.
5. Remove the coolant air bleed hose (1) from the pipe (2).

1. Install the coolant air bleed hose (1) to the pipe (2).
2. Position the hose clamp at the pipe.
3. Install the coolant air bleed hose to the throttle body.
4. Position the coolant air bleed hose clamp at the throttle body.
5. If necessary, install the engine sight shield. Refer to «Upper Intake Manifold Sight Shield Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/mechanical/#engine-mechanical-53l-60l-62l-repair-instructions-on-vehicle) for the 4.8L, 5.3L, and 6.0L engines.
6. Add engine coolant, if necessary.

1. Remove the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-repair-instructions) .
2. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .
3. Reposition the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
4. Remove the radiator vent inlet hose (2) from the coolant air bleed pipe fitting.
5. Reposition the radiator inlet hose clamp (3) at the water pump.
6. Remove the radiator inlet hose from the water pump.
7. Reposition the radiator inlet hose and vent inlet hose out of the way.
8. Remove the accessory drive belt. Refer to «Drive Belt Replacement - Accessory»(/cadillac/escalade/gmt900-2006-2014/remont/mechanical/#engine-mechanical-53l-60l-62l-repair-instructions-on-vehicle) .
9. Reposition the radiator outlet hose clamp at the water pump.
10. Remove the radiator outlet hose from the water pump.
11. Reposition the outlet hose out of the way.
12. Reposition the radiator surge tank outlet hose clamp at the water pump (1).
13. Remove the radiator surge tank outlet hose (2) from the water pump.
14. Reposition the outlet hose out of the way.
15. Reposition the heater inlet hose clamp (1) at the water pump.
16. Remove the heater inlet hose (2) from the water pump.
17. Reposition the inlet hose out of the way.
18. Remove the water pump bolts (301).
19. Remove the water pump (300) and gaskets (309). Discard the gaskets.

Note. All gaskets surfaces are to be free of oil or other foreign material during assembly.

1. Inspect the drained coolant for sand or other debris, flush the system as needed. Refer to «Flushing»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__flushing) .
2. Inspect and clear the radiator vent hose fitting, if necessary. There is a small 2.0 mm (0.080 in) orifice (vent hose fitting) in the neck of the radiator where the coolant vent hose from the engine attaches to the radiator.
3. Position the water pump (300) and NEW gaskets (306) to the engine block.
4. Install the water pump bolts (301). Tighten: Tighten the bolts a first pass to 15 N.m (11 lb ft). Tighten the bolts a final pass to 30 N.m (22 lb ft).
5. Position and install the heater inlet hose (2) to the water pump.
6. Position the heater inlet hose clamp (1) at the water pump.
7. Position and install the radiator surge tank outlet hose (2) to the water pump.
8. Position the radiator surge tank outlet hose clamp at the water pump (1).
9. Position and install the radiator outlet hose to the water pump.
10. Position the radiator outlet hose clamp at the water pump.
11. Install the accessory drive belt. Refer to «Drive Belt Replacement - Accessory»(/cadillac/escalade/gmt900-2006-2014/remont/mechanical/#engine-mechanical-53l-60l-62l-repair-instructions-on-vehicle) .
12. Position the radiator inlet hose and vent inlet hose to the correct position.
13. Install the radiator inlet hose to the water pump.
14. Position the radiator inlet hose clamp (3) at the water pump.
15. Install the radiator vent inlet hose (2) to the coolant air bleed pipe fitting.
16. Position the radiator vent inlet hose clamp (1) at the coolant air bleed pipe fitting.
17. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .
18. Install the air cleaner outlet duct. Refer to «Air Cleaner Resonator Outlet Duct Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-repair-instructions) .

1. Loosen the air cleaner outlet duct clamps from the throttle body.
2. Loosen the air cleaner outlet duct clamps from the mass airflow sensor (2).
3. Remove the air cleaner outlet duct.
4. If equipped remove the throttle body heater hose retainer from the fan shroud.
5. If equipped remove the inlet radiator hose retainer from the fan shroud.
6. Remove the fan shroud retainers.
7. Remove the fan shroud bolts
8. Remove the upper fan shroud.

1. Install the upper fan shroud.
2. Install the fan shroud bolts. Tighten: Tighten the bolts to 9 N.m (80 lb in).
3. Install the fan shroud retainers.
4. If equipped install the inlet radiator hose retainer to the fan shroud
5. If equipped install the throttle body heater hose retainer to the fan shroud.
6. Install the air cleaner outlet duct.
7. Tighten the air cleaner outlet duct clamp at the throttle body. Tighten: Tighten the clamp to 4 N.m (35 lb in).
8. Tighten the air cleaner outlet duct clamp at the mass airflow sensor (2). Tighten: Tighten the clamp to 4 N.m (35 lb in).

1. Remove the radiator. Refer to «Radiator Replacement (HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Disengage the two clips from the radiator.
3. If equipped with engine oil cooler, remove the oil cooler hose clip from the lower fan shroud.
4. Remove the shroud from the vehicle.

1. Install the lower fan shroud and ensure it is centered over lower radiator support.
2. Engage the two clips from the radiator.
3. If equipped with the engine oil cooler, Install the oil cooler hose clip to the lower fan shroud.
4. Install the radiator. Refer to «Radiator Replacement (HP2)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 19

Scheme 20

Scheme 21

1. Drain the cooling system/engine block. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
3. Remove the oil pan skid plate bolts and plate, if equipped.
4. For vehicles with regular production option (RPO) L76 (6.0L), perform the following steps. Otherwise, proceed to step 9.
5. Remove the oil cooler hose bracket bolt (1), if equipped.
6. Remove the oil cooler hose adapter bolts (2), if equipped.
7. Remove and discard the oil cooler hose adapter gasket, if equipped.
8. Position the oil cooler hose adapter end out of the way, if equipped.
9. Disconnect the coolant heater cord electrical connector.
10. Remove the coolant heater from the engine block.
11. Remove any burrs, sealer, or other rough spots.

1. If reusing the old coolant heater, apply thread sealant GM P/N 12346004 (Canadian P/N 10953480), or equivalent to the threads.
2. Install the coolant heater to the engine block and tighten to 50 N.m (37 lb ft).
3. Connect the coolant heater cord electrical connector.
4. For vehicles with RPO L76 (6.0L) perform the following steps otherwise proceed to step 9.
5. Position the oil cooler hose adapter end, if equipped.
6. Install a NEW oil cooler hose adapter gasket, if equipped.
7. If equipped, install the oil cooler hose adapter bolts (2) And tighten to 12 N.m (106 lb in).
8. If equipped, install the oil cooler hose bracket bolt (1) and tighten to 25 N.m (18 lb ft).
9. If equipped, position and install the oil pan skid plate and bolts and tighten to 20 N.m (15 lb ft)
10. Lower the vehicle.
11. Fill the cooling system/engine block. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .

1. Drain the cooling system/engine block. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
3. For 1500 series vehicles, remove the oil pan skid plate bolts and plate, if equipped.
4. For 2500 series vehicle, remove the front 2 oil pan skid plate bolts, loosen the 2 rear bolts and remove the skid plate, if equipped.
5. For vehicles with regular production option (RPO) LY6 (6.0L) perform the following steps otherwise proceed to step 10.
6. Remove the oil cooler hose bracket bolt (1).
7. Remove the oil cooler hose adapter bolts (2).
8. Remove and discard the oil cooler hose adapter gasket.
9. Reposition the oil cooler hose adapter end out of the way.
10. Disconnect the coolant heater cord electrical connector.
11. Remove the coolant heater from the engine block.
12. Remove any burrs, sealer, or other rough spots.

1. If reusing the old coolant heater, apply thread sealant GM P/N 12346004 (Canadian P/N 10953480), or equivalent to the threads.
2. Install the coolant heater to the engine block and tighten to 50 N.m (37 lb ft).
3. Connect the coolant heater cord electrical connector.
4. For vehicles with RPO LY6 (6.0L) perform the following steps otherwise proceed to step 9.
5. Position the oil cooler hose adapter end.
6. Install a NEW oil cooler hose adapter gasket.
7. Install the oil cooler hose adapter bolts (2) and tighten to 12 N.m (106 lb in).
8. Install the oil cooler hose bracket bolt (1) and tighten to 25 N.m (18 lb ft).
9. If equipped, for 2500 series vehicles, position the oil pan skid plate and install the 2 front bolts and tighten the 2 rear bolts and tighten to 20 N.m (15 lb ft)
10. If equipped, for 1500 series vehicles position and install the oil pan skid plate and bolts and tighten to 20 N.m (15 lb ft).
11. Lower the vehicle.
12. Fill the cooling system/engine block. Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
2. Remove the oil pan skid plate bolts and plate, if equipped.
3. Disconnect the coolant heater cord electrical connector.
4. Remove the coolant heater cord retainer (5) from the frame.
5. Remove the coolant heater cord clip (6) from the front brake front pipe.
6. Lower the vehicle.
7. Remove the coolant heater cord bolt (4) from the frame.
8. Remove the coolant heater cord clip (2) from the chassis harness.
9. Remove the coolant heater cord clip (1) from the front spring stud.
10. Remove the coolant heater cord from the vehicle.

1. Install the coolant heater cord to the vehicle.
2. Install the coolant heater cord clip (1) to the front spring stud.
3. Install the coolant heater cord clip (2) to the chassis harness.
4. Position the coolant heater cord clip to the frame and install the coolant heater cord bolt (4) and tighten to 8 N.m (71 lb in).
5. Raise the vehicle.
6. Install the coolant heater cord clip (6) to the front brake front pipe.
7. Position the coolant heater cord clip to the frame and install the coolant heater cord retainer (5).
8. Connect the coolant heater cord electrical connector.
9. If equipped, position and install the oil pan skid plate and bolts and tighten to 20 N.m (15 lb ft).
10. Lower the vehicle.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
2. Remove the oil pan skid plate bolts and plate, if equipped.
3. Disconnect the coolant heater cord electrical connector.
4. Remove the coolant heater cord clip (3) from the engine harness channel.
5. Remove the coolant heater cord clip (1) from the power steering gear outlet hose.
6. Lower the vehicle.
7. Remove the coolant heater cord bolt (2) from the frame.
8. Remove the coolant heater cord from the vehicle.

1. Install the coolant heater cord to the vehicle.
2. Position the coolant heater cord clip to the frame and install the coolant heater cord bolt (2) and tighten to 8 N.m (71 lb in).
3. Raise the vehicle.
4. Install the coolant heater cord clip (1) to the power steering gear outlet hose.
5. Install the coolant heater cord clip (3) to the engine harness channel.
6. Connect the coolant heater cord electrical connector.
7. If equipped position and install the oil pan skid plate and boltsand tighten to 20 N.m (15 lb ft).
8. Lower the vehicle.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
2. Remove the front 2 oil pan skid plate bolts, loosen the 2 rear bolts and remove the skid plate, if equipped.
3. Disconnect the coolant heater cord electrical connector.
4. Remove the coolant heater cord clip (1) from the front brake front pipes.
5. Remove the coolant heater cord clip retainer (2) from the frame.
6. Lower the vehicle.
7. Remove the coolant heater cord bolt (3) from the frame.
8. Remove the coolant heater cord from the vehicle.

1. Install the coolant heater cord to the vehicle.
2. Position the coolant heater cord clip to the frame and install the coolant heater cord bolt (3) and tighten to 8 N.m (71 lb in).
3. Raise the vehicle.
4. Install the coolant heater cord clip retainer (2) to the frame.
5. Install the coolant heater cord clip (1) to the front brake front pipes.
6. Connect the coolant heater cord electrical connector.
7. If equipped, position the oil pan skid plate and install the 2 front bolts and tighten the 2 rear bolts and tighten to 20 N.m (15 lb ft).
8. Lower the vehicle.

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 G100 and G101.

Low Speed Operation

The ECM applies 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 series/parallel (S/P) cooling fan speed control relay. The result is a series circuit that operates both fans at low speed.

High Speed Operation

The ECM applies a ground to the coil side of the cooling fan low speed relay, the S/P cooling fan speed control relay, and the cooling fan high speed relay. When energized, the 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 S/P speed control 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.

The hybrid engine cooling fan system consists of two electrical cooling fans, two resistors, three engine control module (ECM) fan output control drivers, and five fan relays. The relays are arranged in a series/parallel configuration that allows the ECM to operate the fans at low, medium, or high speed depending on engine cooling requirements. The ECM controls the five relays by grounding the relay control circuits.

The ECM applies a ground to the fan 1 control circuit for the low fan relay. This energizes the low fan relay coil, closes the relay contacts, and supplies battery positive voltage from the fan 1 fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the de-energized fan control relay, through the right cooling fan in-line resistor, and right cooling fan. The result is a series circuit with both fans running at a reduced speed.

Medium Speed Operation

The ECM applies a ground to the fan 2 control circuit, which energizes a bank of three relays consisting of the FAN Mid 1 relay, the fan control relay, and the FAN Mid 2 relay. When these three relays are energized the Mid 1 relay supplies battery voltage to the left cooling fan through the left cooling fan resistor. A direct ground path is provided for the left fan through the energized fan control relay. At the same time the Mid 2 relay is energized which applies battery voltage to the right cooling fan through the right cooling fan resistor. The result is a parallel circuit where each fan has voltage applied through a separate resistor, causing each fan to operate at a medium speed.

The ECM applies a ground to the fan 1, fan 2, and fan 3 relay control circuits simultaneously, which activates all five relays. This allows battery voltage to be applied directly to the right cooling fan from the Fan High relay, and battery voltage to be applied directly to the left fan from the Fan Low relay. The left fan is supplied a direct path to ground through the energized fan control relay. This arrangement provides each fan with direct battery voltage and its own ground path. The result is a parallel circuit with both fans running at full speed. When the ECM is commanding a fan relay ON, the voltage of the control circuit should be low, near 0 volts. When the ECM is commanding a fan relay OFF, the voltage of the control circuit should be high, near battery voltage.

ENGINE COOLANT HOT

The instrument panel cluster (IPC) displays ENGINE COOLANT HOT message when the IPC receives a class 2 message from the powertrain control module (PCM) requesting illumination of this driver warning.

ENGINE OVERHEATED

The IPC displays ENGINE OVERHEATED message when the IPC receives a class 2 message from the PCM requesting illumination of this driver warning.

REDUCED ENGINE POWER

The IPC displays REDUCED ENGINE POWER message when the IPC detects a reduced engine power condition from the PCM. The IPC receives a class 2 message from the PCM requesting illumination when the engine temperature reaches 132°C (270°F).

Coolant Heater

The optional engine coolant heater (RPO K05) operates using 110-volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather 29°C (20°F). 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.

Illustration Tool Number/ Description GE 47716 Vac-N-Fill Coolant Refill Tool J 24460-1 Cooling System Pressure Tester J 24731 Tempil Stick J 26568 Coolant and Battery Fluid Tester J 38185 Hose Clamp Pliers J 41240 or J 46406-A Fan Clutch Remover and Installer Kit includes (36mm) Wrench J 41240-2 Fan Clutch Wrench (36mm) J 41240-5A Fan Clutch Wrench (47mm) J 42401 Radiator Cap/Surge Tank Test Adapter J 43244 Relay Puller Pliers J 46406-1 Fan Clutch Remover and Installer

Scheme 22

Scheme 23

Scheme 24

Scheme 25

Scheme 26

Scheme 27

Scheme 28

Scheme 29

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Component Connector End Views
• Powertrain Component Views
• 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 (Attached to Wire Harness)
• DTC P254F
• Instrument Cluster Description and Operation
• Audible Warnings Description and Operation
• Coolant in Combustion Chamber
• Coolant in Engine Oil
• Diagnostic Trouble Code (DTC) List - Vehicle
• Hybrid Modes of Operation Description
• DTC P0117 or P0118 (Without L96)
• Engine Oil and Oil Filter Replacement
• Engine Coolant/Water in Transmission
• Lifting and Jacking the Vehicle
• Fastener Caution
• Approximate Fluid Capacities
• Air Cleaner Assembly Replacement
• Air Cleaner Assembly Replacement
• Generator Control Module Coolant Inlet Hose Replacement
• Upper Intake Manifold Sight Shield Replacement
• Engine Shield Replacement
• Shield Replacement
• DTC P0480 or P0481 (without HP2)
• Cooling System Draining and Filling (Static Fill)
• Engine Overheating
• Loss of Coolant
• Engine Fails To Reach Normal Operating Temperature
• Cooling System Leak Testing
• Pressure Cap Testing
• Flushing
• Engine Oil Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection