Engine Cooling System Cadillac SRX II рестайлинг

Fastener Tightening Specifications

Fastener Tightening Specifications

Scheme 1

Scheme 2

Diagnostic Code Index

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

KR20P Cooling Fan Medium Speed Relay

KR20C Cooling Fan Low Speed Relay

KR20D Cooling Fan High Speed Relay

KR20E Cooling Fan Speed Control Relay

KR20F Cooling Fan Relay

Typical Scan Tool Data

Cooling Fan Relay 1 and Cooling Fan Relays 2 and 3 Control Circuit Open, Low, and High Voltage Test Status

Cooling Fan Relays 1, 2 and 3 Control Circuit Open, Low, and High Voltage Test Status

Circuit/System Description

The engine cooling fan system is composed of one cooling fan, a series of 5 relays, the engine control module (ECM), and the associated wiring. The cooling fan assembly includes two individual resistors mounted to each side of the cooling fan shroud. This combination of components enables the ECM to operate the cooling fan at 3 speeds using two fan control circuits.

To operate the fan, 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.

Conditions for Running the DTC

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

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

DTCs P0480, P0691, and P0692 are a Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0480, P0691, and P0692 are a Type B DTCs.

Diagnostic Aids

1. A condition with the powertrain relay or the bussed ignition voltage circuit to the cooling fan relay may set this DTC.
2. 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 scan tool Cooling Fan Relay Command parameters to know which fans are being commanded ON by the ECM.
3. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates the fan at a low speed Cooling Fan Relay 2 and 3 operates the fan at a medium speed Cooling Fan Relay 1, 2 and 3 operates the fan at a high speed
4. When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.

Reference Information

Schematic Reference

Engine Heating/Cooling Schematics

Connector End View Reference

1. «COMPONENT CONNECTOR END VIEWS - INDEX»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index)
2. «Electrical Center Identification Views»(/cadillac/srx/ii-2012-2016/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-electrical-center-identification-views)

Description and Operation

Cooling Fan Description and Operation (LF1, LFW, LFX)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.
2. Verify an audible click is heard or felt from each cooling fan relay when commanding the cooling fan ON and OFF with a scan tool. If a click is not heard or felt at each of the relays Refer to Circuit/System Testing (below). If a click is heard or felt at each of the relays
3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
4. Verify the DTC does not set. If the DTC sets Refer to Circuit/System Testing (below). If the DTC does not set
5. All OK.

Circuit/System Testing

1. Ignition OFF, disconnect and remove the underhood Fuse Block and housing.
2. Connect the engine harness connectors X2 and X3 to the Fuse Block.
3. Connect a DMM, set on the diode setting, between KR20F Cooling Fan Relay control circuit terminal X1-28 and ground.
4. Ignition ON, verify the DMM reading is greater than 2.5 V or displays O.L. If 2.5 V or less Ignition OFF, and all vehicle systems OFF, it may take up to 2 minutes for all vehicle systems to power down. Disconnect the X1 harness connector at the K20 Engine Control Module. Test for infinite resistance between the appropriate relay coil control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K20 Engine Control Module. If greater than 2.5 V or displays O.L.
5. Verify the DMM reading is less than 1 V when commanding the Cooling Fan Relays ON with a scan tool. If 1 V or greater Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module, ignition ON. Test for less than 1 V between the appropriate relay coil control circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V. Ignition OFF. Test for less than 2 ohms in the appropriate KR20 Cooling Fan Relay control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If less than 1 V
6. Test or replace the X50A Fuse Block - Underhood.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(/cadillac/srx/ii-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) , «Relay Replacement (Attached to Wire Harness)»(/cadillac/srx/ii-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
2. «Fuse Block Replacement»(/cadillac/srx/ii-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
3. «Control Module References»(/cadillac/srx/ii-2012-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, programming, and setup

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

KR20P COOL FAN 2 Relay

KR20C COOL FAN 3 Relay

KR20D COOL FAN 1 Relay

KR20E COOL FAN 5 Relay

KR20F COOL FAN 4 Relay

The engine cooling fan system is composed of one cooling fan, a series of 5 relays, the engine control module (ECM), and the associated wiring. The cooling fan assembly includes two individual resistors mounted to each side of the cooling fan shroud. This combination of components enables the ECM to operate the cooling fan at 3 speeds using two fan control circuits.

To operate the fan, 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.

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

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

DTCs P0481, P0693, and P0694 are Type B DTCs.

DTCs P0481, P0693, and P0694 are Type B DTCs.

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

Schematic Reference

Engine Heating/Cooling Schematics

Connector End View Reference

1. «COMPONENT CONNECTOR END VIEWS - INDEX»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index)
2. «Electrical Center Identification Views»(/cadillac/srx/ii-2012-2016/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-electrical-center-identification-views)

Description and Operation

Cooling Fan Description and Operation (LF1, LFW, LFX)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON.
2. Verify an audible click is heard or felt from each cooling fan relay when commanding the cooling fan ON and OFF with a scan tool. If a click is not heard or felt at each of the relays Refer to Circuit/System Testing (below). If a click is heard or felt at each of the relays
3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
4. Verify the DTC does not set. If the DTC sets Refer to Circuit/System Testing (below). If the DTC does not set
5. All OK.

1. Ignition OFF, disconnect the KR20 cooling fan relays listed below: KR20P Cooling Fan Medium Speed Relay KR20D Cooling Fan High Speed Relay
2. Ignition ON, verify that a test lamp illuminates between ground and the KR20P relay coil ignition circuit terminal 86. If the test lamp does not illuminate Ignition OFF, and all vehicle systems OFF, it may take up to 2 minutes for all vehicle systems to power down. Test for less than 2 ohms in the ignition circuit, end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, test or replace the KR75 Engine Controls Ignition Relay. If the test lamp illuminates
3. Connect a DMM, set on the diode setting, between a control circuit terminal listed below and ground: KR20P Cooling Fan Medium Speed Relay terminal 85 KR20D Cooling Fan High Speed Relay terminal 86
4. Verify the DMM reading is greater than 2.5 V or displays O.L. If 2.5 V or less Ignition OFF, and all vehicle systems OFF, it may take up to 2 minutes for all vehicle systems to power down. Disconnect the X1 harness connector at the K20 Engine Control Module. Test for infinite resistance between the appropriate relay coil control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K20 Engine Control Module. If greater than 2.5 V or displays O.L.
5. Verify the DMM reading is less than 1 V when commanding the Cooling Fan Relays ON with a scan tool. If 1 V or greater Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module, ignition ON. Test for less than 1 V between the appropriate KR20 Cooling Fan Relay control circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V. Ignition OFF. Test for less than 2 ohms in the appropriate KR20 Cooling Fan Relay control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If less than 1 V
6. Test or replace the appropriate KR20 Cooling Fan Relay.

Component Testing

1. Ignition OFF, disconnect the KR20 cooling fan relay.
2. Test for 60-100 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. The DMM should display OL. 30 and 86 30 and 87 30 and 85 85 and 87 If less than the specified range, replace the KR20 cooling fan relay.
4. 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 (Within an Electrical Center)»(/cadillac/srx/ii-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) , «Relay Replacement (Attached to Wire Harness)»(/cadillac/srx/ii-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
2. «Control Module References»(/cadillac/srx/ii-2012-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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

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

The ECM detects that engine coolant temperature is warmer than 132°C (270°F) for 2 seconds or greater.

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

DTC P1258 is a Type A DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

1. «Cooling Fan Description and Operation (LF1, LFW, LFX)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system__cooling-fan-description-and-operation-lf1)
2. «Instrument Cluster Description and Operation»(/cadillac/srx/ii-2012-2016/remont/gauges-instrument-panels/#instrument-panel-system-displays-and-gauges)
3. «Indicator/Warning Message Description and Operation»(/cadillac/srx/ii-2012-2016/remont/gauges-instrument-panels/#instrument-panel-system-displays-and-gauges)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

K20 Engine Control Module: Scan Tool Information (LFX or LFW) for scan tool information

1. Ignition ON.
2. Verify DTC P0480, P0481, P0691, P0692, P0693, or P0694 is not set. If a DTC is set Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) . If no DTCs is set
3. Verify the cooling fan operates at each available speed as commanded with a scan tool. Cooling fan does not operate Refer to «Cooling Fan Inoperative»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) . Cooling fan operates
4. Verify that the engine does not overheat. Engine overheats Refer to «Engine Overheating»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system__engine-overheating) . Engine does not overheat
5. Operate the vehicle within the Conditions for Running the DTC. If the DTC sets Refer to «Symptoms - Engine Cooling»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) . If the DTC does not set
6. All OK

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/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) and verify all of the following items: Engine control module (ECM) and malfunction indicator lamp (MIL) are operating correctly. There are no diagnostic trouble codes (DTCs) stored. Scan tool data is within a normal operating range.
2. Verify the customer concern.
3. Perform the Visual/Physical Inspection in this section. The visual/physical inspection is extremely important, and can lead to correcting a condition without additional testing. It may also help reveal the cause of an intermittent condition.
4. Locate the correct symptom. Perform the tests and inspections associated with the symptom.

Review the entire cooling system operation in order to familiarize yourself with the system functions. Refer to Cooling Fan Description and Operation (LF1, LFW, LFX) , and Cooling System Description and Operation .

Visual/Physical Inspection

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

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

Identifying Intermittent Conditions

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

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

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

Symptom List

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

1. «Cooling Fan Always On»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Cooling Fan Inoperative»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
3. «Engine Overheating»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system__engine-overheating)
4. «Loss of Coolant»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant)
5. «Thermostat Diagnosis»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system__thermostat-diagnosis)
6. «Engine Fails To Reach Normal Operating Temperature»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine cooling system contains an engine coolant level switch to alert the driver in the event of a low coolant level. The coolant level switch is mounted at the lowest point in the cooling system surge tank. The low coolant level switch is an electromagnetic device that works in conjunction with a float ring inside the surge tank. The switch is enclosed in a housing molded into the bottom of the surge tank, which isolates it from the coolant in the tank. The float ring is located inside the surge tank and is secured to the switch housing. When the tank is full, the float ring is in close proximity to the sensing element on the switch and the switch circuit closes. If the amount of coolant in the surge tank drops below the level of the switch sensing element, the coolant level switch opens. The coolant level signal circuit is monitored by the instrument panel cluster (IPC). The IPC supplies ignition voltage to the switch on the signal circuit, and a ground is used to complete the circuit. If the IPC detects an open circuit, or a high voltage condition on the signal circuit for greater than 10 seconds, the IPC displays a low coolant level message.

Schematic Reference

Engine Heating/Cooling Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition OFF, verify the radiator surge tank is filled with engine coolant to the correct level. Coolant not at correct level Refer to «Loss of Coolant»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant) for further diagnosis. Coolant level OK
2. Ignition ON, observe the scan tool Coolant Level Switch parameter. The parameter should display Closed. Displays Open Refer to Circuit/System Testing (below). Displays Closed
3. All OK.

Note. Circuit/System Verification must be performed before performing the Circuit/System Testing.

1. Ignition OFF, remove the radiator surge tank fill cap.
2. Verify the coolant level float ring is secured, and is free to move up and down on the coolant level switch housing. Float ring not OK Clean or replace the radiator surge tank. Float ring OK
3. Ignition OFF, disconnect the harness connector at the B33 Coolant Level Switch.
4. Test for less than 5 ohms between the ground circuit terminal 1 and ground. If 5 ohms or greater Ignition OFF, and all vehicle systems OFF, it may take up to 2 minutes for all vehicles systems to power down. Test for less than 2 ohms in the ground circuit, end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If less than 5 ohms
5. Install a 3 A fused jumper wire between the signal circuit terminal 2 and the ground circuit terminal 1.
6. Ignition ON, verify the scan tool Coolant Level Switch parameter displays Closed. Displays Open Ignition OFF, disconnect the P16 Instrument Panel Cluster connector. Test the for less than 2 ohms in the coolant level signal circuit, end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms Ignition ON, test for less that 1 V between the B33 Coolant Level Switch signal circuit terminal 2 and ground. If 1 V or greater, repair the short to voltage on the signal circuit. Displays Closed
7. Replace the B33 Coolant Level Switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Radiator Surge Tank Replacement (LF1, LFW, or LFX)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Engine Coolant Level Indicator Module Replacement»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) for coolant level switch replacement.

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of the diagnostic category.

The engine cooling fan system is composed of one cooling fan, a series of 5 relays, the engine control module (ECM), and the associated wiring. The cooling fan assembly includes two resistors. This combination of components enables the ECM to operate the cooling fan at 3 speeds using two fan control circuits.

1. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates the fan at a low speed Cooling Fan Relay 2 and 3 operates the fan at a medium speed Cooling Fan Relay 1, 2 and 3 operates the fan at a high speed
2. Certain resistance conditions with IAT or ECT sensors may cause unwarranted cooling fan activation. If the ECM is commanding the cooling fans ON for no apparent reason and without any component or system DTCs set, the IAT or ECT sensor may be skewed. If this condition is suspected, refer to the Temperature Versus Resistance tables in the appropriate engine controls subsection.
3. If the cooling fan operates at high speed when the ECM is requesting medium speed operation, test or replace the KR20E Cooling Fan Speed Control Relay.

Schematic Reference

Engine Heating/Cooling Schematics

Connector End View Reference

1. «COMPONENT CONNECTOR END VIEWS - INDEX»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index)
2. «Electrical Center Identification Views»(/cadillac/srx/ii-2012-2016/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-electrical-center-identification-views)

Description and Operation

Cooling Fan Description and Operation (LF1, LFW, LFX)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON.
2. Verify that there are no cooling system DTCs set. If any DTCs are set Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) . If no DTCs are set
3. Verify the scan tool parameters listed below display OFF. Cooling Fan Relay 1 Command Cooling Fan Relays 2 and 3 Command If a scan tool parameter displays ON Refer to «Diagnostic Aids»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) and «Symptoms - Engine Cooling»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) for further diagnosis. If both scan tool parameters display OFF
4. Verify that the fan is not activated. If the fan is operating Refer to Circuit/System Testing (below). If the fan is OFF
5. All OK.

1. Ignition OFF, disconnect each KR20 cooling fan relay one at a time, in the order listed below, ignition ON: KR20C Cooling Fan Low Speed Relay KR20P Cooling Fan Medium Speed Relay KR20D Cooling Fan High Speed Relay
2. Verify that the cooling fan is not activated after each relay is removed. If the cooling fan is ON with all of the listed relays removed Ignition OFF, disconnect the harness connector at the G10 Cooling Fan Motor, ignition ON. Test for less than 1 V between ground and the relay controlled output circuit terminal listed below: KR20C Cooling Fan Low Speed Relay terminal 30 KR20P Cooling Fan Medium Speed Relay terminal 30 KR20D Cooling Fan High Speed Relay terminal 30 If 1 V or greater, repair the short to voltage in the appropriate circuit. If the cooling fan is OFF after a listed relay is removed
3. Replace the appropriate KR20 Cooling Fan Relay.

1. Ignition OFF.
2. Disconnect a KR20 Cooling Fan Relay.
3. Test for 70-110 ohms between terminals 85/2 and 86/1. 95-135 ohms for the KR20F Cooling Fan Relay. If less than or greater than the specified range Replace the KR20 Cooling Fan Relay. If within the specified range
4. Test for infinite resistance between the following terminals: 30/3 and 86/1 30/3 and 87/5 30/3 and 85/2 85/2 and 87/5 If less than infinite resistance Replace the KR20 Cooling Fan Relay. If infinite resistance
5. Install a 20 A fused jumper wire between relay terminal 85/2 and 12 V.
6. Install a jumper wire between relay terminal 86/1 and ground.
7. Test for less than 2 ohms between terminals 30/3 and 87/5. If 2 ohms or greater Replace the KR20 Cooling Fan Relay. If less than 2 ohms
8. All OK.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine cooling fan system is composed of one cooling fan, a series of 5 relays, the engine control module (ECM), and the associated wiring. The cooling fan assembly includes two individual resistors mounted to each side of the cooling fan shroud. This combination of components enables the ECM to operate the cooling fan at 3 speeds using two fan control circuits.

1. The scan tool cooling fan output control operates as follows: Cooling Fan Relay 1 operates the fan at a low speed Cooling Fan Relay 2 and 3 operates the fan at a medium speed Cooling Fan Relay 1, 2 and 3 operates the fan at a high speed
2. When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.
3. If the cooling fan operates at high speed when the ECM is requesting medium speed operation, test or replace the KR20E Cooling Fan Speed Control Relay and Fuse Block.

Schematic Reference

Engine Heating/Cooling Schematics

Connector End View Reference

1. «COMPONENT CONNECTOR END VIEWS - INDEX»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-component-connector-end-views-index)
2. «Electrical Center Identification Views»(/cadillac/srx/ii-2012-2016/remont/electrical-component-locations/#wiring-systems-and-power-management-component-locator-electrical-center-identification-views)

Description and Operation

Cooling Fan Description and Operation (LF1, LFW, LFX)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON.
2. Verify that DTC P0480, P0481, P0691, P0692, P0693, or P0694 is not set. If a DTC is set Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) . If no DTC is set
3. Verify that the cooling fan operates at low, medium, and high speed, when commanding the appropriate cooling fan relays ON and OFF with a scan tool. If the cooling fan does not operate at all speeds Refer to Circuit/System Testing (below). If the cooling fan operates at all speeds
4. All OK.

Inoperative in All Speeds

1. Ignition OFF, disconnect the harness connector at the G10 Cooling Fan Motor.
2. Verify a test lamp illuminates between the ground circuit terminal 1 and B+ If the test lamp does not illuminate Ignition OFF, remove the test lamp. Test for less than 2 ohms in the ground circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If the test lamp illuminates
3. Test or replace the G10 Cooling Fan Motor. Replace the cooling fan fuses if necessary.

Low, Medium or High Speed Inoperative

1. Ignition OFF, disconnect the following relays: KR20C Cooling Fan Low Speed Relay KR20D Cooling Fan High Speed Relay KR20P Cooling Fan Medium Speed Relay
2. Verify a test lamp illuminates between ground and each of the cooling fan relay B+ circuit terminals listed below: KR20C Cooling Fan Low Speed Relay terminal 87 KR20D Cooling Fan High Speed Relay terminal 87 KR20P Cooling Fan Medium Speed Relay terminal 87 If the test lamp does not illuminate and the circuit fuse is good Ignition OFF, remove the test lamp. Test for less than 2 ohms in the appropriate relay B+ circuit, end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF, disconnect the harness connector at the G10 Cooling Fan Motor. Test for infinite resistance between the appropriate relay controlled output circuit terminal listed below and ground: KR20C Cooling Fan Low Speed Relay terminal 30 KR20D Cooling Fan High Speed Relay terminal 30 KR20P Cooling Fan Medium Speed Relay terminal 30 If less than infinite resistance, repair the short to ground in the circuit. If infinite resistance, test or replace the G10 Cooling Fan Motor, replace the fuse as necessary. If the test lamp illuminates
3. Ignition ON, command the cooling fan ON at low speed.
4. Connect a test lamp between B+ and the KR20C Cooling Fan Low Speed Relay control circuit terminal 86. The test lamp should illuminate. If the test lamp does not illuminate Disconnect the X50A Fuse Block - Underhood harness connector. Test for less than 2 ohms between Fuse Block harness connector terminal X1-48 and ground. If greater than 2 ohms, repair the open/high resistance in the circuit. If less than 2 ohms, replace the X50A Fuse Block - Underhood. If the test lamp illuminates
5. Ignition ON, command the cooling fan ON at high speed.
6. Connect a test lamp between ground and the KR20D Cooling Fan High Speed Relay coil ignition voltage terminal 85. The test lamp should illuminate. If the test lamp does not illuminate Replace the X50A Cooling Fan Speed Control Relay If the test lamp illuminates
7. Ignition OFF, install the previously removed cooling fan relays.
8. Ignition ON, connect a test lamp between ground and the cooling fan circuit terminals listed below. Command the cooling fan ON at High speed. The test lamp should illuminate at each terminal. R10A Cooling Fan Resistor - Low Speed terminal 1 R10B Cooling Fan Resistor - Medium Speed terminal 1 G10 Cooling Fan Motor B+ supply circuit terminal 2 If the test lamp does not illuminate Test for less than 2 ohms between the appropriate cooling fan relay controlled output circuit end to end. If greater than 2 ohms, repair the open/high resistance in the circuit. If less than 2 ohms, test or replace the appropriate KR20 Cooling Fan Relay. If the test lamp illuminates
9. Ignition OFF, connect the harness connectors to the cooling fan resistors.
10. Ignition ON, connect a test lamp between ground and the G10 Cooling Fan Motor B+ supply circuit terminal 2. Command the cooling fan ON at Low and Medium speed. The test lamp should illuminate as commanded in each speed. If the test lamp does not illuminate Test for less than 2 ohms between the G10 Cooling Fan Motor B+ supply circuit terminal 2 and the appropriate R10 Cooling Fan Resister terminal 2 If greater than 2 ohms, repair the open/high resistance in the circuit. If less than 2 ohms, test or replace the appropriate R10 Cooling Fan Resistor. If the test lamp illuminates
11. If all of the circuits and components test normal, test or replace the G10 Cooling Fan Motor.

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 60-100 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. The DMM should display OL. 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified range, replace the relay.
4. Install a 20 A fused jumper wire between relay terminal 86 and B+. Install a jumper wire between relay terminal 85 and ground. Test for less than 2ohms between terminals 30 and 87. If greater than the specified range, replace the relay.

Cool Fan 5 Printed Circuit Board Relay

1. Ignition OFF, disconnect the following cooling fan relays: KR20D Cooling Fan High Speed Relay KR20C Cooling Fan Low Speed Relay
2. Test for 190-230 ohms between KR20C Cooling Fan Low Speed Relay terminals 85 and 86 in the Fuse Block. If not within the specified range, replace the Fuse Block.
3. Connect a 3 A fused jumper wire between ground and KR20C Cooling Fan Low Speed Relay terminal 86, at the Fuse Block.
4. Ignition ON, verify a test lamp illuminates between ground and KR20D Cooling Fan High Speed Relay terminal 85, at the Fuse Block. If the test lamp does not illuminate, replace the Fuse Block.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Within an Electrical Center)»(/cadillac/srx/ii-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) , «Relay Replacement (Attached to Wire Harness)»(/cadillac/srx/ii-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
2. «Engine Coolant Fan Resistor Replacement - Right Side (LF1)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
3. «Engine Coolant Fan Resistor Replacement - Left Side (LF1)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
4. «Engine Coolant Fan Motor Replacement (LF1)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
5. «Fuse Block Replacement»(/cadillac/srx/ii-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)

Engine Overheating

Engine Overheating

Loss of Coolant

Loss of Coolant

Thermostat Diagnosis

Thermostat Diagnosis

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/srx/ii-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The coolant heater operates using 110 V AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather. The coolant heater also helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. There is an internal thermal switch in the coolant heater cord that prevents operation above -18°C (0°F). A weather shield on the cord is provided to protect the plug when not in use.

Electrical Information Reference

1. «Circuit Testing»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/srx/ii-2012-2016/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

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

1. Ignition OFF, disconnect the coolant heater cord from the E19 Coolant Heater.
2. Test for 30-40 ohms between the terminals of the E19 Coolant Heater. If not within 30-40 ohms Replace the E19 Coolant Heater. If within 30-40 ohms
3. Test for infinite resistance between each terminal of the E19 Coolant Heater and ground. If less than infinite resistance Replace the E19 Coolant Heater. If infinite resistance
4. Test or replace the coolant heater cord.

Perform the Diagnostic Repair Verification after completing the diagnostic repair.

1. «Engine Coolant Heater Replacement (LFW, LFX)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
2. «Coolant Heater Cord Replacement (LFW, LFX)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)

Special Tools

J 24731 Tempil Stick

For equivalent regional tools, refer to Special Tools

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

Thermostat Test Procedure Using Tempil Sticks

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

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

For equivalent regional tools, Refer to Special Tools

Pressure Cap Testing

1. Remove the pressure cap.
2. Wash the pressure cap sealing surface with water.
3. Use the GE-24460-01 Cooling System Pressure Tester (1) with GE-42401-A Radiator Cap/Surge Tank Test Adapter Kit (2) in order to test the pressure cap.
4. Test the pressure cap for the following conditions: Pressure release when the GE-24460-01 Cooling System Pressure Tester exceeds the pressure rating of the pressure cap. Maintain the rated pressure for at least 10 seconds. Note the rate of pressure loss.
5. Replace the pressure cap under the following conditions: The pressure cap does not release pressure which exceeds the rated pressure of the cap. The pressure cap does not hold the rated pressure.

Cooling System Leak Testing

Special Tools

1. GE-24460-01 Cooling System Pressure Tester
2. GE-42401-A Radiator Cap/Surge Tank Test Adapter

For equivalent regional tools, Refer to Special Tools

1. Remove the pressure cap.
2. Test the operation of the pressure cap. Refer to «Pressure Cap Testing»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system__pressure-cap-testing) .
3. Wash the pressure cap mating surface with water.
4. Use the GE-24460-01 Cooling System Pressure Tester with the GE-42401-3 Radiator Cap/Surge Tank Test Adapter and GE-42401-2 Radiator Cap/Surge Tank Test Adapter in order to apply pressure to the cooling system. Do not exceed the pressure cap rating.
5. The cooling system should hold the rated pressure for at least 2 minutes. Observe the gauge for any pressure loss.
6. Repair any leaks as required.

GE-26568 Coolant and Battery Fluid Tester

For equivalent regional tools, Refer to Special Tools

Draining Procedure

1. Remove the coolant pressure cap from the radiator surge tank.
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/srx/ii-2012-2016/remont/hoistjack/#general-information) .
3. Remove the radiator air lower deflector. Refer to «Radiator Air Lower Deflector Replacement»(/cadillac/srx/ii-2012-2016/remont/exterior-body-panels/#bumpers-and-fascias)
4. Place a drain pan under the drain cock.
5. Loosen the radiator drain cock (1).
6. Drain the cooling system.
7. Lower the vehicle.
8. Inspect the coolant.
9. 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/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system__flushing) .

Filling Procedure

1. Raise and support the vehicle.
2. Tighten the radiator drain cock (1) to 2 N.m (18 lb in).
3. Install the radiator air lower deflector. Refer to «Radiator Air Lower Deflector Replacement»(/cadillac/srx/ii-2012-2016/remont/exterior-body-panels/#bumpers-and-fascias)
4. Lower the vehicle.
5. Slowly fill the radiator with a 50/50 coolant mixture until the coolant level reaches the base of the radiator surge tank. Refer to «Approximate Fluid Capacities»(/cadillac/srx/ii-2012-2016/remont/lubrication-system/#maintenance-and-lubrication__approximate-fluid-capacities) .
6. Allow 30 seconds for the coolant level to stabilize and continue to fill the coolant filler neck until the level stabilizes for at least 2 minutes.
7. Start the engine and allow to the engine to idle in PARK or NEUTRAL with the parking brake engaged.
8. Slowly fill the coolant mixture until the level stabilizes at the base of the radiator surge tank.
9. Install the coolant pressure cap.
10. Raise the engine RPM to 2500 RPM for 30-40 seconds.
11. Shut the engine OFF.
12. Allow the engine to cool, remove coolant fill cap and repeat steps 4-10 until the coolant level has completely stabilized within the radiator surge tank.
13. Inspect the concentration of the engine coolant using the GE-26568 Coolant and Battery Fluid Tester.
14. Inspect and if necessary, fill the coolant reservoir bottle as necessary.
15. Rinse away any excess coolant from the engine and the engine compartment.
16. Inspect the cooling system for leaks.
17. Top off the radiator surge tank if necessary.

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

For equivalent regional tools, Refer to Special Tools

1. Remove the coolant pressure cap.
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/srx/ii-2012-2016/remont/hoistjack/#general-information) .
3. Place a drain pan under the drain cock.
4. Remove the radiator drain cock.
5. Drain the cooling system.
6. Lower the vehicle.
7. Inspect the coolant.
8. Follow the appropriate procedure based on the condition of the coolant. Normal in appearance-Follow the filling procedure. Discolored-Follow the flush procedure. Refer to «Flushing»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system__flushing) .

Vac-N-Fill Procedure

1. Install the GE-42401-A Radiator Cap and Surge Tank Test Adapter onto the coolant surge tank.
2. Attach the Vac N Fill cap to the GE-42401-A Radiator Cap and Surge Tank Test Adapter.
3. Attach the vacuum gauge assembly to the Vac N Fill cap.
4. Attach the fill hose to the barb fitting on the vacuum gauge assembly. Ensure that the valve is closed.
5. Pour the coolant mixture into the graduated reservoir.
6. Place the fill hose in the graduated reservoir.
7. Install the vacuum tank on the graduated reservoir with the fill hose routed through the cut-out area in the vacuum tank.
8. Attach the venturi assembly to the vacuum tank.
9. Attach a shop air hose to the venturi assembly. Ensure the valve on the venturi assembly is closed.
10. Attach the vacuum hose to the vacuum gauge assembly and the vacuum tank.
11. Open the valve on the venturi assembly. The vacuum gauge will begin to rise and a hissing noise will be present.
12. Continue to draw vacuum until the needle stops rising. This should be 610-660 mm Hg (24-26 in Hg). Cooling hoses may start to collapse. This is normal due to vacuum draw.
13. To aid in the fill process, position the graduated reservoir above the coolant fill port.
14. Slowly open the valve on the vacuum gauge assembly. When the coolant reaches the top of the fill hose, close the valve. This will eliminate air from the fill hose.
15. Close the valve on the venturi assembly.
16. If there is a suspected leak in the cooling system, allow the system to stabilize under vacuum and monitor for vacuum loss. If vacuum loss is observed, refer to «Loss of Coolant»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant) .
17. Open the valve on the vacuum gauge assembly. The vacuum gauge will drop as coolant is drawn into the system.
18. Once the vacuum gauge reaches zero, close the valve on the vacuum gauge assembly and repeat steps 11-17.
19. Detach the Vac N Fill cap from the GE-42401-A Radiator Cap and Surge Tank Test Adapter.
20. Remove the GE-42401-A Radiator Cap and Surge Tank Test Adapter from the coolant surge tank.
21. Add coolant to the system as necessary.
22. Inspect the concentration of the coolant mixture using GE-26568 Coolant and Battery Fluid Tester.
23. Detach the vacuum hose from the vacuum gauge assembly.
24. Attach the extraction hose to the vacuum hose.
25. Open the valve on the venturi assembly to start a vacuum draw.
26. Use the extraction hose to draw out coolant to the proper level.
27. The vacuum tank has a drain valve on the bottom of the tank. Open the valve to drain coolant from the vacuum tank into a suitable container for disposal.
28. Install the surge tank cap.

Flushing

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

1. Block the drive wheels.
2. Place the transmission in PARK (P).
3. Engage the park brake.
4. Run the engine until the thermostat opens.
5. Stop the engine.
6. Follow the drain and fill procedure using only clean drinkable water. Repeat the procedure if necessary, until the fluid is nearly colorless. Refer to «Cooling System Draining and Filling (Static Fill LF1)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
7. Fill the cooling system when flushing is complete. Refer to «Cooling System Draining and Filling (Static Fill LF1)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 3

Radiator Surge Tank Replacement (LF1, LFW, or LFX)

Scheme 4

Radiator Surge Tank Inlet Hose Replacement (LF1, LFW or LFX)

Scheme 5

Radiator Surge Tank Outlet Hose Replacement (LF1, LFW or LFX)

BO-38185 Hose Clamp Pliers

For equivalent regional tools, Refer to Special Tools

Removal Procedure

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill LF1)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/cadillac/srx/ii-2012-2016/remont/mechanical/#engine-mechanical-36l-lfx-repair-instructions-on-vehicle) .
3. Disengage tension on the radiator inlet hose clamp (1) at the radiator using BO-38185 Hose Clamp Pliers.
4. Remove the radiator inlet hose (2) from the radiator.
5. Unclip radiator inlet hose connector (1) and remove the radiator inlet hose (2) from the engine.
6. Remove the radiator inlet hose from the vehicle.

Installation Procedure

1. Install radiator inlet hose to the vehicle.
2. Clip the radiator inlet hose (2) to the engine.
3. Install the radiator inlet hose (2) to the radiator.
4. Engage tension on the radiator inlet hose clamp (1) at the radiator using BO-38185 Hose Clamp Pliers.
5. Install the intake manifold cover. Refer to «Intake Manifold Cover Replacement»(/cadillac/srx/ii-2012-2016/remont/mechanical/#engine-mechanical-36l-lfx-repair-instructions-on-vehicle) .
6. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill LF1)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) .

BO-38185 Hose Clamp Pliers

For equivalent regional tools, Refer to Special Tools

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill LF1)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/cadillac/srx/ii-2012-2016/remont/hoistjack/#general-information) .
3. Remove the radiator air lower deflector. Refer to «Radiator Air Lower Deflector Replacement»(/cadillac/srx/ii-2012-2016/remont/exterior-body-panels/#bumpers-and-fascias) .
4. Disengage tension on the radiator outlet hose clamp (1) at the radiator using BO-38185 Hose Clamp Pliers.
5. Remove the radiator outlet hose (2) from the radiator.
6. Disengage tension on the radiator outlet hose clamp (1) at the engine using BO-38185 Hose Clamp Pliers.
7. Remove the radiator outlet hose (2) from the engine.
8. Remove the radiator outlet hose from the vehicle.

1. Install radiator outlet hose to the vehicle.
2. Install the radiator outlet hose (2) to the engine.
3. Engage tension on the radiator outlet hose clamp (1) at the engine using BO-38185 Hose Clamp Pliers.
4. Install the radiator outlet hose (2) to the radiator.
5. Engage tension on the radiator outlet hose clamp (1) at the radiator using BO-38185 Hose Clamp Pliers.
6. Install the radiator air lower deflector. Refer to «Radiator Air Lower Deflector Replacement»(/cadillac/srx/ii-2012-2016/remont/exterior-body-panels/#bumpers-and-fascias) .
7. Lower the vehicle.
8. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill LF1)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 6

Engine Coolant Fan Replacement (LF1, LFW or LFX)

Scheme 7

Engine Coolant Fan Motor Replacement (LF1)

Scheme 8

Cooling Fan and Shroud Replacement (LF1, LFW or LFX)

Scheme 9

Engine Coolant Fan Resistor Replacement - Right Side (LF1)

Scheme 10

Engine Coolant Fan Resistor Replacement - Left Side (LF1)

Scheme 11

Engine Coolant Level Indicator Module Replacement

Scheme 12

Engine Coolant Thermostat Housing Replacement (LFW, LFX)

Scheme 13

Engine Coolant Thermostat Replacement (LFW, LFX)

Scheme 14

Engine Coolant Air Bleed Pipe Replacement (LFW, LFX)

Scheme 15

Water Outlet Replacement

EN 46104 Water Pump Pulley Holder

For equivalent regional tools, refer to Special Tools .

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill LF1)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the generator drive belt. Refer to «Drive Belt Replacement»(/cadillac/srx/ii-2012-2016/remont/mechanical/#engine-mechanical-36l-lfx-repair-instructions-on-vehicle) .
3. Use the EN 46104 water pump pulley holder (1) to retain the pulley.
4. Remove the water pump pulley fasteners and DISCARD the fasteners.
5. Remove the water pump pulley.
6. Remove the water pump fasteners and DISCARD the fasteners.
7. Remove the water pump.
8. Remove and DISCARD the water pump seal.
9. Carefully clean the water pump sealing surfaces.

1. Install a NEW water pump seal.
2. Install the water pump.
3. Install the NEW water pump fasteners and hand tighten the water pump fasteners.
4. Tighten the water pump fasteners in sequence. On the initial pass, tighten the fasteners in sequence to 10 (89 lb in). On the second pass, tighten the fasteners in sequence to 10 (89 lb in). On the final pass, tighten the fasteners in sequence shown an additional 45 degrees.
5. Install the water pump pulley and the NEW water pump pulley fasteners.
6. Use the EN 46104 water pump pulley holder (1) to hold the pulley.
7. Install the water pump pulley fasteners and tighten to 12 (108 lb in) .
8. Install the generator drive belt. Refer to «Drive Belt Replacement»(/cadillac/srx/ii-2012-2016/remont/mechanical/#engine-mechanical-36l-lfx-repair-instructions-on-vehicle) .
9. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill LF1)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 16

Radiator Drain Cock Replacement (LF1, LFW or LFX)

1. Drain the cooling system. Refer to «Cooling System Draining and Filling (Static Fill LF1)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) .
2. Remove the front bumper facia. Refer to «Front Bumper Fascia Replacement»(/cadillac/srx/ii-2012-2016/remont/exterior-body-panels/#bumpers-and-fascias__front-bumper-fascia-replacement)
3. Remove the front compartment front sight shield. Refer to «Front Compartment Front Sight Shield Replacement»(/cadillac/srx/ii-2012-2016/remont/exteriorinterior-trim/#bolted-exterior-body-panels-and-closures)
4. Remove the primary latch bracket. Refer to «Hood Primary Latch Bracket Replacement»(/cadillac/srx/ii-2012-2016/remont/exteriorinterior-trim/#bolted-exterior-body-panels-and-closures)
5. Remove the cooling fan and shroud. Refer to «Cooling Fan and Shroud Replacement (LF1, LFW or LFX)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
6. Remove the radiator air upper seal. Refer to «Radiator Air Upper Seal Replacement»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
7. Remove the radiator air lower seal. Refer to «Radiator Air Lower Seal Replacement»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
8. Remove the radiator air side seal. Refer to «Radiator Air Seal Replacement»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
9. Remove the radiator air side baffels. Refer to «Radiator Air Side Baffle Replacement - Left Side»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) , and «Radiator Air Side Baffle Replacement - Right Side»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
10. Remove the air conditioning condenser. Refer to «Air Conditioning Condenser Replacement»(/cadillac/srx/ii-2012-2016/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
11. Remove the radiator inlet hose. Refer to «Radiator Inlet Hose Replacement (LF1, LFW or LFX)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
12. Remove the radiator outlet hose. Refer to «Radiator Outlet Hose Replacement (LF1, LFW or LFX)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
13. Remove the radiator upper support bracket bolts (1).
14. Remove the radiator upper support brackets (2).
15. Remove the radiator (1) from the vehicle.

1. Install the radiator (1) to the vehicle.
2. Install the radiator upper support brackets (2).
3. Install the radiator upper support bracket bolts (1) and tighten to 9 N.m (80 lb in).
4. Install the radiator outlet hose. Refer to «Radiator Outlet Hose Replacement (LF1, LFW or LFX)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
5. Install the radiator inlet hose. Refer to «Radiator Inlet Hose Replacement (LF1, LFW or LFX)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
6. Install the air conditioning condenser. Refer to «Air Conditioning Condenser Replacement»(/cadillac/srx/ii-2012-2016/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
7. Install the radiator air side baffels. Refer to «Radiator Air Side Baffle Replacement - Left Side»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) , and «Radiator Air Side Baffle Replacement - Right Side»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
8. Install the radiator air side seal. Refer to «Radiator Air Seal Replacement»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
9. Install the radiator air lower seal. Refer to «Radiator Air Lower Seal Replacement»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
10. Install the radiator air upper seal. Refer to «Radiator Air Upper Seal Replacement»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
11. Install the cooling fan and shroud. Refer to «Cooling Fan and Shroud Replacement (LF1, LFW or LFX)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system)
12. Install the primary latch bracket. Refer to «Hood Primary Latch Bracket Replacement»(/cadillac/srx/ii-2012-2016/remont/exteriorinterior-trim/#bolted-exterior-body-panels-and-closures)
13. Install the front compartment front sight shield. Refer to «Front Compartment Front Sight Shield Replacement»(/cadillac/srx/ii-2012-2016/remont/exteriorinterior-trim/#bolted-exterior-body-panels-and-closures)
14. Install the front bumper facia. Refer to «Front Bumper Fascia Replacement»(/cadillac/srx/ii-2012-2016/remont/exterior-body-panels/#bumpers-and-fascias__front-bumper-fascia-replacement)
15. Fill the cooling system. Refer to «Cooling System Draining and Filling (Static Fill LF1)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) , «Cooling System Draining and Filling (GE 47716)»(/cadillac/srx/ii-2012-2016/remont/cooling-system-mechanical/#engine-cooling-system) .

Scheme 17

Radiator Air Side Baffle Replacement - Left Side

Scheme 18

Radiator Air Side Baffle Replacement - Right Side

Scheme 19

Radiator Air Seal Replacement

Scheme 20

Radiator Air Upper Seal Replacement

Scheme 21

Radiator Air Lower Seal Replacement

Scheme 22

Engine Coolant Heater Replacement (LFW, LFX)

Scheme 23

Coolant Heater Cord Replacement (LFW, LFX)

Cooling Fan Description and Operation (LF1, LFW, LFX)

The engine cooling fan system is composed of one electric cooling fan, a series of 5 relays, the engine control module (ECM), and the associated wiring. The cooling fan assembly includes two separate resistors mounted in the cooling fan shroud. This combination of components enables the ECM to operate the cooling fan at 3 speeds using two fan control circuits.

Low Speed Operation

The ECM applies ground at the FAN 1 control circuit for the coil side of the cooling fan relay. The energized cooling fan relay completes a ground, through the switch side of the relay, for the coils of the cooling fan low speed relay and the cooling fan speed control relay. The speed control relay activates and supplies B+ to the coil side of the cooling fan high speed relay. The high speed relay remains inactive because the ECM is not commanding the FAN 2 control circuit ON. The energized low speed relay switch closes to supply B+ through the external low speed resistor, to the engine cooling fan motor. The result is cooling fan operation at a reduced speed.

Medium Speed Operation

The ECM applies ground at the FAN 2 control circuit for the coil side of the cooling fan high speed, and medium speed relays. The high speed relay remains inactive because the ECM is not commanding the FAN 1 control circuit ON. The energized medium speed relay switch closes to supply B+ through the external medium speed resistor, to the engine cooling fan motor. The result is cooling fan operation at a medium speed.

High Speed Operation

The ECM applies ground at the FAN 1 control circuit for the coil side of the cooling fan relay. The energized cooling fan relay completes a ground, through the switch side of the relay, for the coil of the cooling fan speed control relay. The energized speed control relay switch closes to supply B+ to the coil side of cooling fan high speed relay. Simultaneously, the ECM applies ground at the FAN 2 control circuit for the coil side of the cooling fan high speed relay. The energized high speed relay switch closes to supply B+ directly to the engine cooling fan motor, by-passing the external resistors. The result is cooling fan operation at full speed.

Cooling Fan Description and Operation

For cooling fan description and operation, refer to Cooling Fan Description and Operation (LF1, LFW, LFX) .

Cooling Fan Control - Two Fan System

The engine cooling fan system consists of 2 puller type electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the engine control module (ECM) to operate both fans together at low or high speeds. The cooling fans and the fan relays receive battery positive voltage from the underhood fuse block. The ground path is provided at G104.

During low speed operation, the ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the low fan 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 cooling fan s/p relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. After a 3-second delay, the ECM supplies a ground path for the high speed fan relay and the cooling fan s/p relay through the high speed cooling fan relay control circuit. This energizes the cooling fan s/p relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the high speed fan relay coil is energized closing the relay contacts and provides battery positive voltage from the high fan fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.

The ECM commands the low speed cooling fans ON under the following conditions

1. Engine coolant temperature exceeds approximately 94.5°C (202°F).
2. A/C refrigerant pressure exceeds 1447 kPa (210 psi).
3. After the vehicle is shut OFF if the engine coolant temperature at key-off is greater than 101°C (214°F) the low speed fans will run for a minimum of 60 seconds After 60 seconds, if the coolant temperature drops below 101°C (214°F) the fans will shut OFF. The fans will automatically shut OFF after 3 minutes regardless of coolant temperature.

The ECM commands the high speed fans ON under the following conditions

1. Engine coolant temperature exceeds 104°C (220°F).
2. A/C refrigerant pressure exceeds 1824 kPa (265 psi).
3. When certain DTCs set.

At idle and very low vehicle speeds the cooling fans are only allowed to increase in speed if required. This insures idle stability by preventing the fans from cycling between high and low speed.

Cooling Fan Control - Heavy Duty Cooling

The engine cooling fan system consists of 2 electrical pusher, 2 electrical puller type cooling fans and 3 fan relays. The low speed, high speed, and S/P relays are arranged in a series/parallel configuration that allows the ECM to operate the left cooling fan and right cooling fan together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block. The ground path is provided at G104.

During low speed operation, the ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the low fan 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 cooling fan S/P relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. After a 3-second delay, the ECM supplies a ground path for the high speed fan relay and the cooling fan S/P relay through the high speed cooling fan relay control circuit. This energizes the cooling fan S/P relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the high speed fan relay coil is energized closing the relay contacts and provides battery positive voltage from the high fan fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.

The ECM commands the low speed fans on under the following conditions

1. Engine coolant temperature exceeds 94.5°C (202°F).
2. A/C refrigerant pressure exceeds 1447 kPa (210 psi).
3. After the vehicle is shut OFF if the engine coolant temperature at key-off is greater than 101°C (214°F) the low speed fans will run for a minimum of 60 seconds. After 60 seconds, if the coolant temperature drops below 101°C (214°F) the fans will shut OFF. The fans will automatically shut OFF after 4 minutes regardless of the coolant temperature.

The ECM commands the high speed fans ON under the following conditions

1. Engine coolant temperature exceeds 104°C (220°F).
2. A/C refrigerant pressure exceeds 1824 kPa (265 psi).
3. When certain DTCs set.

At idle and very low vehicle speeds the cooling fans are only allowed to increase in speed if required. This ensures idle stability by preventing the fans from cycling between high and low speed.

Engine Coolant

Engine coolant is the key element of the heating system. The engine thermostat controls the normal engine operating coolant temperature. Coolant pumped out of the engine block enters the heater core through the inlet heater hose. The air flowing through the HVAC module absorbs the heat of the coolant flowing through the heater core. The coolant then exits the heater core through the heater outlet hose. To prevent the coolant from boiling after the engine is turned off an after-boil/heater coolant pump is used.

The HVAC control module will command the after-boil/heater coolant pump on when the engine is off under the following conditions

1. The engine is OFF.
2. The engine coolant temperature is greater than 101°C (214°F).

The above coolant flow circuits are designed to show the coolant flow related to the coolant by-pass valve positions only. The thermostat function and thermostat coolant flow paths are not shown.

Coolant Warning Messages

The radio will display the following messages if the following conditions exist in the cooling system.

1. Engine hot-A/C OFF, is displayed if the coolant temperature is greater than 117°C (243°F) for domestic vehicles or 115°C (239°F) for imports.
2. Engine coolant hot-idle engine, is displayed if the coolant temperature is greater than 118°C (245°F).
3. Engine overheated-stop engine, is displayed if the coolant temperature is greater than 123°C (253°F).

Coolant Level Control

The engine cooling system contains an engine coolant level switch to alert the driver in the event of a low coolant level. When the engine coolant level in the surge tank falls below a certain level, the coolant level switch opens. When the HVAC control module detects an open, or a high voltage level, on the coolant level indicator control circuit for at least 10 seconds, the control module sends a class 2 message to the radio requesting display of the low coolant level message. A 10-second delay occurs before the HVAC control module sends the class 2 message, to prevent the message from being displayed due to coolant sloshing in the surge tank.

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.

The cooling system's function is to maintain an efficient engine operating temperature during all engine speeds and operating conditions. The cooling system is designed to remove approximately one-third of the heat produced by the burning of the air-fuel mixture. When the engine is cold, the system cools slowly or not at all. This allows the engine to warm quickly.

Cooling Cycle

The thermostat is located between the radiator outlet and the water pump inlet. At normal operating temperature, coolant is drawn from the radiator outlet and into the water pump inlet by the water pump. In cold conditions, the thermostat will bypass the radiator, and the pump will draw coolant directly from the engine outlet.

Coolant is then pumped through the water pump outlet and into the engine block. In the engine block, the coolant circulates through the water jackets surrounding the cylinders where it absorbs heat.

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

Coolant is also directed to the throttle body. There it circulates through passages in the casting. During initial warm-up, the coolant assists in warming the throttle body. During normal operating temperatures, the coolant assists in keeping the throttle body cool.

From the cylinder heads, the coolant is then forced to the engine outlet. Coolant leaves the engine through four different routes

1. Through the engine outlet fitting to the radiator. This path is blocked at cold conditions by the thermostat at the engine inlet fitting.
2. Through the radiator bypass.
3. To the heater core for passenger compartment heat and defrost.
4. Through the vent hose to the surge tank, providing continuous direction of the cooling system.

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

Coolant

The engine coolant is a solution made up of a 50-50 mixture of DEX-COOL and clean drinkable water. The coolant solution carries excess heat away from the engine to the radiator, where the heat is dissipated to the atmosphere.

Radiator

The radiator is a heat exchanger. It consists of a core and two tanks. The aluminum core is a crossflow tube and fin design. This is a brazed tube with convoluted louvered fin design. Separate tubes and fins are stacked together with a manifold at each end. The entire core assembly is then brazed forming a homogeneous unified structure. The fins allow for efficient heat transfer from the coolant to the atmosphere. The inlet and outlet tanks are molded with a high temperature, glass reinforced nylon plastic. The tank and gasket is supplied as an assembly with silicone gasket attached to the tank. The tanks are clamped to the core with clinch tabs. The tabs are part of the aluminum header at each end of the core. The radiator also has a drain cock which is located in the bottom of the passenger side tank. The drain cock includes the drain cock and drain cock seal.

The radiator removes heat from the coolant passing through it. The fins on the core absorb heat from the coolant passing through the tubes. As air passes between the fins, it absorbs heat and cools the coolant.

During vehicle use, the coolant heats and expands. The coolant that is displaced by this expansion flows into the surge tank. As the coolant circulates, air is allowed to exit. Coolant without bubbles absorbs heat much better than coolant with bubbles.

Pressure Cap

The pressure cap is a cap that seals and pressurizes the cooling system. It contains a blow off or pressure valve and a vacuum or atmospheric valve. The pressure valve is held against its seat by a spring and protects the radiator by relieving pressure if it exceeds 18 psi. The vacuum valve is held against its seat by a spring, which permits opening of the valve to relieve vacuum created in the cooling system as it cools off. The vacuum, if not relieved, could cause the radiator hoses to collapse.

The pressure cap allows pressure in the cooling system to build up. As the pressure builds, the boiling point of the coolant goes up as well. Therefore, the coolant can be safely run at a temperature higher than the boiling point of the coolant at atmospheric pressure. The hotter the coolant is, the faster the heat moves from the radiator to the cooler passing air. However, if the pressure exceeds the strength of the spring, the pressure valve rises so that the excess pressure can escape. When the engine cools down, the temperature of the coolant drops and a vacuum is created in the cooling system. This vacuum causes the vacuum valve to open, allowing outside air into the cooling system. This equalizes the pressure in the cooling system with atmospheric pressure, thus preventing the radiator hoses from collapsing.

Surge Tank

The surge tank is a plastic tank with a pressure cap mounted to it. The tank is mounted at a point higher than all other coolant passages. The surge tank provides an air space in the cooling system. The air space allows the coolant to expand and contract. The surge tank also provides a coolant fill point and a central air bleed location.

During vehicle use, the coolant heats and expands. The coolant that is displaced by this expansion flows into the surge tank. As the coolant circulates, air is allowed to exit. This is an advantage to the cooling system. Coolant without bubbles absorbs heat much better than coolant with bubbles.

Air Baffles and Seals

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

Water Pump

The water pump is a centrifugal vane impeller type pump. The pump consists of a housing and an impeller. The impeller is a flat plate mounted on the pump shaft with a series of flat or curved blades or vanes. When the impeller rotates, the coolant between the vanes is thrown outward by centrifugal force. The impeller shaft is supported by one or more sealed bearings. The sealed bearings never need to be lubricated. Grease cannot leak out, dirt and water cannot get in as long as the seal is not damaged or worn.

The purpose of the water pump is to circulate coolant throughout the cooling system. The water pump is driven by the crankshaft via the drive belt.

Thermostat

The thermostat is a coolant flow control component. Its purpose is to regulate the operating temperature of the engine. It utilizes a temperature sensitive wax-pellet element. The element connects to a valve through a piston. When the element is heated, it expands and exerts pressure against a rubber diaphragm. This pressure forces the valve to open. As the element is cooled, it contracts. This contraction allows a spring to push the valve closed.

When the coolant temperature is below the rated thermostat opening temperature, the thermostat valve remains closed. This prevents circulation of the coolant to the radiator and allows the engine to warm up quickly. After the coolant temperature reaches rated thermostat opening temperature, the thermostat valve will open. The coolant is then allowed to circulate through the thermostat to the radiator where the engine heat is dissipated to the atmosphere. The thermostat also provides a restriction in the cooling system, even after it has opened. This restriction creates a pressure difference which prevents cavitation at the water pump and forces coolant to circulate through the engine block.

Engine Oil Heat Exchanger

The engine oil heat exchanger is mounted to the top of the engine block, under the intake manifold flange. Oil is pumped through the oil cooler inlet pipe to the heat exchanger, back through the oil cooler outlet pipe, and then to the oil passages in the engine for lubrication. The exchanger provides the following 2 functions

1. Engine coolant warms up faster than the engine oil. During cold operation, the coolant warms the oil and provides better flow during cold engine operation.
2. After the engine reaches normal operating temperature, the engine oil temperature will exceed the engine coolant temperature. The coolant flowing through the engine oil cooler will absorb heat from the engine oil. Cooling the engine oil extends oil life and helps reduce internal engine wear.

Transmission Oil Cooler-Two Fan System

The transmission oil cooler is a heat exchanger located in the bottom tank of the radiator. The transmission oil temperature is regulated by the temperature of the coolant leaving the radiator and passing over the heat exchanger. Lines from the transmission bring oil pumped at a high pressure to the cooler and back to the transmission.

Transmission Oil Cooler-Three Fan System

There are 2 transmission oil coolers in a series in the heavy duty transmission oil cooler system. The initial transmission oil cooler is a heat exchanger located in the bottom tank of the radiator. The transmission oil temperature is partially regulated by the temperature of the coolant leaving the radiator and passing over the heat exchanger. Lines from the transmission bring oil pumped at a high pressure to the cooler. The oil out of the cooler is plumbed to an air-to-oil cooler in front of the A/C condenser. This cooler provides additional cooling for heavy duty trailering. The transmission oil is then directed back to the transmission.

Transmission Oil Cooler Lines

The transmission oil cooler lines use quick connect fittings on the transmission oil cooler lines near the A/C compressor. The quick connect fittings must be removed using a special tool. The transmission oil cooler is an oil-to-air heat exchanger located between the A/C condenser and the radiator. The transmission oil temperature is regulated by the temperature of the air leaving the A/C condenser and passing over the heat exchanger. Lines from the transmission bring oil pumped at a high pressure to the cooler and back to the transmission. A thermal bypass valve is located external to the transmission where the transmission oil cooler lines connect to the transmission. This provides uninterrupted transmission oil flow for low ambient temperature conditions.

Power Steering Oil Cooler

Some vehicles are equipped with a power steering oil cooler located either between the radiator and condenser (Heavy Duty) or in front of the engine. This cooler transfers heat from the power steering system to the air passing through the condenser and radiator. The cooler uses constant tension clamps on the hose connections to the cooler.

Illustration Tool Number/ Description EN 46104 J 46104 Water Pump Pulley Holding Tool GE 47716 Vac N Fill Coolant Refill Tool EN 24460-A J 24460-01 Cooling System Pressure Tester GE 24731 J 24731 Tempilstick GE 26568 J 26568 Coolant and Battery Fluid Tester EN 28410 J 28410 Gasket Remover (Aluminum Components DT 41623-B J 41623-B Quick Connect Tool BO 38185 J 38185 Hose Clamp Pliers GE 47622 Hose Clamp Pliers BO 38778 J 38778 Door Trim Clip Remover GE 42401-A J 42401 Radiator Cap and Surge Tank Test Adapter EL 43244 J 43244 Relay Puller Pliers

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See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• COMPONENT CONNECTOR END VIEWS - INDEX
• Electrical Center Identification Views
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Control Module References
• Diagnostic Repair Verification
• Relay Replacement (Within an Electrical Center)
• Engine Controls Schematics
• Instrument Cluster Description and Operation
• K20 Engine Control Module: Scan Tool Information (LFX or LFW)
• Diagnostic Trouble Code (DTC) List - Vehicle
• Drive Belt Tensioner Diagnosis
• Engine Oil and Oil Filter Replacement (LF1, LFW or LFX)
• Engine Coolant/Water in Transmission
• Coolant in Combustion Chamber
• Coolant in Engine Oil
• Lifting and Jacking the Vehicle
• Radiator Air Lower Deflector Replacement
• Fastener Caution
• Approximate Fluid Capacities
• Battery Tray Replacement
• Fuel Pipe Shield Replacement
• Power Steering Fluid Reservoir Replacement (LF1, LFW, or LFX)
• Front Bumper Fascia Replacement
• Front Compartment Front Sight Shield Replacement
• Air Conditioning Condenser Replacement
• DTC P0480, P0691, or P0692
• Cooling Fan Description and Operation (LF1, LFW, LFX)
• Engine Overheating
• Loss of Coolant
• Thermostat Diagnosis
• Flushing
• Cooling System Leak Testing
• Pressure Cap Testing