Engine Cooling System: Other Cadillac STS I facelift

Circuit/System Verification

Verify cooling fan operation using the scan tool commands listed below

1. Fan relay 1 is ON-Both fans run at low speed.
2. Fan relays 2 and 3 are ON-The right fan runs at high speed, the left fan is OFF.
3. Fan relays 1, 2 and 3 are ON-Both fans run at high speed.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Engine Coolant Fan Replacement (LY7)»(ref-338194-S24275741032009081700000) or «Engine Coolant Fan Replacement (LH2 Heavy Duty Cooling)»(ref-338194-S16171444302009081700000) or «Engine Coolant Fan Replacement (LH2 Standard Cooling)»(ref-338194-S04299447752009081700000)
2. «Relay Replacement (Attached to Wire Harness)»(ref-338153-S01872743142009081700000) or «Relay Replacement (Within an Electrical Center)»(ref-338153-S35866912282009081700000)
3. «Underhood Electrical Center or Junction Block Replacement»(ref-338153-S30235940762009081700000)
4. «Control Module References»(ref-338152-S12253781062009081700000) for ECM replacement, setup, and programming

Reference Information (V6)

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-338151-S30248766082009081700000)
2. «Connector Repairs»(ref-338151-S41110648952009081700000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-338151-S41477264612009081700000)
4. «Wiring Repairs»(ref-338151-S09708660722009081700000)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification (V6)

1. Ignition ON, command the appropriate fan relay ON and OFF with a scan tool. Listen or feel the relay click.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Repair Procedures (V6)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Attached to Wire Harness)»(ref-338153-S01872743142009081700000) or «Relay Replacement (Within an Electrical Center)»(ref-338153-S35866912282009081700000)
2. «Control Module References»(ref-338152-S12253781062009081700000) for ECM replacement, setup, and programming

Description and Operation

1. «Cooling System Description and Operation»(ref-338194-S08795213082009081700000)
2. «Instrument Cluster Description and Operation»(ref-338124-S19896443462009081700000)
3. «Indicator/Warning Message Description and Operation»(ref-338124-S36615779072009081700000)
4. «Audible Warnings Description and Operation»(ref-338124-S01891604562009081700000)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Observe the engine coolant level. The engine coolant level should be within operating range. Refer to Capacities - Approximate Fluid, and Engine Coolant in the Owner's Manual.
2. Ensure that the vehicle has the correct engine coolant, with correct concentration, and is not old, contaminated or contains additives. Refer to Recommended Fluids and Lubricants in the Owner's Manual.
3. Inspect the cooling system for the following: Cooling system leaks Kinked or pinched hoses, especially at the radiator Loose, missing, or damaged radiator air seals or deflectors The radiator and A/C condenser for any air flow obstructions or bent fins-Refer to «Symptoms - Engine Cooling»(ref-338194-S16740533812009081700000) .
4. Command the cooling fans in both low and high speed. If the cooling fans do not operate in both speeds, refer to «Cooling Fan Inoperative (V6)»(ref-338194-S06116001362009081700000) or «Cooling Fan Inoperative (w/RPO LC3 or LH2)»(ref-338194-S00846444062009081700000) .
5. Test the thermostat for correct operation. Refer to «Thermostat Diagnosis»(ref-338194-S03473611072009081700000) .
6. Test the engine cooling system for overheating. Refer to «Engine Overheating»(ref-338194-S10729140912009081700000) .
7. Inspect the water pump and coolant flow for correct operation. Refer to «Water Pump Replacement (V6)»(ref-338194-S08295661812009081700000) or «Water Pump Replacement (LC3)»(ref-338194-S26114230482009081700000) or «Water Pump Replacement (LH2)»(ref-338194-S12362747682009081700000) .
8. Inspect the engine mechanical for worn/leaking/cracked cylinder heads and engine block. Refer to «Coolant in Combustion Chamber»(ref-338165-S18475380032009081700000) and «Coolant in Engine Oil»(ref-338165-S00430990852009081700000) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Reference Information (with RPO LC3 or LH2)

Description and Operation

1. «Cooling System Description and Operation»(ref-338194-S08795213082009081700000)
2. «Instrument Cluster Description and Operation»(ref-338124-S19896443462009081700000)
3. «Indicator/Warning Message Description and Operation»(ref-338124-S36615779072009081700000)
4. «Audible Warnings Description and Operation»(ref-338124-S01891604562009081700000)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification (with RPO LC3 or LH2)

1. Observe the engine coolant level. The engine coolant level should be within operating range. Refer to Capacities - Approximate Fluid, and Engine Coolant in the Owner's Manual.
2. Ensure that the vehicle has the correct engine coolant, with correct concentration, and is not old, contaminated or contains additives. Refer to Recommended Fluids and Lubricants in the Owner's Manual.
3. Inspect the cooling system for the following: Cooling system leaks Kinked or pinched hoses, especially at the radiator Loose, missing, or damaged radiator air seals or deflectors The radiator and A/C condenser for any air flow obstructions or bent fins-Refer to «Symptoms - Engine Cooling»(ref-338194-S16740533812009081700000) .
4. Command the cooling fans in both low and high speed. If the cooling fans do not operate in both speeds, refer to «Cooling Fan Inoperative (V6)»(ref-338194-S06116001362009081700000) or «Cooling Fan Inoperative (w/RPO LC3 or LH2)»(ref-338194-S00846444062009081700000) .

Repair Procedures (with RPO LC3 or LH2)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. Ignition ON, command the auxiliary coolant pump relay ON and OFF with the scan tool. An audible click should be heard when changing between the commanded states.
2. Start the engine, observe the DTC information with a scan tool. DTCs P2600, P2602, or P2603 should not set.
3. Ignition ON, engine off observe the DTC information with a scan tool. DTC P2601 should not set. If DTC P2601 is set refer to the following links: «After Boil Coolant Pump Always On»(ref-338194-S24511889682009081700000) «After Boil Coolant Pump Inoperative»(ref-338194-S03531612282009081700000) «After Boil Coolant Pump Malfunction»(ref-338194-S04348310862009081700000)
4. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming

Symptoms - Engine Cooling

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-338151-S30248766082009081700000)
2. «Connector Repairs»(ref-338151-S41110648952009081700000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-338151-S41477264612009081700000)
4. «Wiring Repairs»(ref-338151-S09708660722009081700000)

Scan Tool Reference

Control Module References for scan tool information

1. Verify that DTCs P0480, P0481, P0691, P0692, P0693 and P0694 are not set. If any cooling system DTCs are set, repair the DTC first. Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(ref-338149-S32129793932009081700000) .
2. Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
3. Ignition ON, observe that the fan is not activated.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-338151-S30248766082009081700000)
2. «Connector Repairs»(ref-338151-S41110648952009081700000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-338151-S41477264612009081700000)
4. «Wiring Repairs»(ref-338151-S09708660722009081700000)

Scan Tool Reference

Control Module References for scan tool information

1. Verify that DTCs P0480, P0481, P0691, P0692, P0693 and P0694 are not set. If any cooling system DTCs are set, repair the DTC first. Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(ref-338149-S32129793932009081700000) .
2. Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
3. Ignition ON, observe that the fan is not activated.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-338151-S30248766082009081700000)
2. «Connector Repairs»(ref-338151-S41110648952009081700000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-338151-S41477264612009081700000)
4. «Wiring Repairs»(ref-338151-S09708660722009081700000)

Scan Tool Reference

Control Module References for scan tool information

1. Verify that DTCs P0480, P0481, P0691, P0692, P0693 and P0694 are not set. If any cooling system DTCs are set, repair the DTC first. Refer to «DTC P0480, P0481, P0691, P0692, P0693, or P0694 (V6)»(ref-338194-S08631424912009081700000) .
2. Ignition ON, command the appropriate fan relay ON and OFF with a scan tool. Verify that the fans turn ON and OFF when changing between the commanded states.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Attached to Wire Harness)»(ref-338153-S01872743142009081700000) or «Relay Replacement (Within an Electrical Center)»(ref-338153-S35866912282009081700000)
2. «Engine Coolant Fan Motor Replacement»(ref-338194-S04471075202009081700000)

Schematic Reference

1. «Electrical Center Identification Views»(ref-338181-S33900845042009081700000)
2. «Engine Cooling Schematics»(ref-338194-S34515868272009081700000)

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-338151-S30248766082009081700000)
2. «Connector Repairs»(ref-338151-S41110648952009081700000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-338151-S41477264612009081700000)
4. «Wiring Repairs»(ref-338151-S09708660722009081700000)

Scan Tool Reference

Control Module References for scan tool information

1. If DTCs P0480 or P0481 are set, then perform those diagnostics first.
2. Ignition ON, command each relay ON and OFF with a scan tool. Feel or listen to verify that each relay turns ON and OFF with each command.

Repair Verification

Ignition ON, command the relay ON and OFF with a scan tool. Observe to verify that the fan turns ON and OFF with each command.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-338151-S30248766082009081700000)
2. «Connector Repairs»(ref-338151-S41110648952009081700000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-338151-S41477264612009081700000)
4. «Wiring Repairs»(ref-338151-S09708660722009081700000)

Scan Tool Reference

Control Module References for scan tool information

1. Verify that DTCs P2600, P2602 and P2603 are not set. If any auxiliary coolant pump DTCs are set, repair the DTC first. Refer to «DTC P2600-P2603»(ref-338194-S05984814262009081700000) .
2. Ignition ON, verify with a scan tool that the ECM is not commanding pump activation.
3. Ignition ON, observe that the pump is not activated.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-338151-S30248766082009081700000)
2. «Connector Repairs»(ref-338151-S41110648952009081700000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-338151-S41477264612009081700000)
4. «Wiring Repairs»(ref-338151-S09708660722009081700000)

Scan Tool Reference

Control Module References for scan tool information

1. Verify that DTCs P2600, P2602 and P2603 are not set. If any auxiliary coolant pump DTCs are set, repair the DTC first. Refer to «DTC P0480, P0481, P0691, P0692, P0693, or P0694 (V6)»(ref-338194-S08631424912009081700000) .
2. Ignition ON, command the auxiliary coolant pump relay ON and OFF with a scan tool. Verify that the pump turns ON and OFF when changing between the commanded states.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Attached to Wire Harness)»(ref-338153-S01872743142009081700000) or «Relay Replacement (Within an Electrical Center)»(ref-338153-S35866912282009081700000)
2. «Auxiliary Water Pump Inlet Hose Replacement»(ref-338194-S34259695872009081700000)
3. «Auxiliary Water Pump Outlet Hose Replacement»(ref-338194-S20142823822009081700000)
4. «Auxiliary Water Pump Replacement (4.6L (LH2) w/RPOs V03/V92)»(ref-338194-S35435467362009081700000) or «Auxiliary Water Pump Replacement (LLT)»(ref-338194-S16646463762009081700000)

Description and Operation

Cooling System Description and Operation

Scan Tool Reference

Control Module References for scan tool information

1. Verify that DTCs P2600, P2602 and P2603 are not set. If any auxiliary coolant pump DTCs are set, repair the DTC first. Refer to «DTC P0480, P0481, P0691, P0692, P0693, or P0694 (V6)»(ref-338194-S08631424912009081700000) .
2. Ignition ON, command the auxiliary coolant pump relay ON and OFF with a scan tool. Verify that the pump turns ON and OFF when changing between the commanded states. If the auxiliary coolant pump does not activate, refer to «After Boil Coolant Pump Inoperative»(ref-338194-S03531612282009081700000) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Auxiliary Water Pump Replacement (4.6L (LH2) w/RPOs V03/V92)»(ref-338194-S35435467362009081700000) or «Auxiliary Water Pump Replacement (LLT)»(ref-338194-S16646463762009081700000)
2. «Auxiliary Water Pump Inlet Hose Replacement»(ref-338194-S34259695872009081700000)
3. «Auxiliary Water Pump Outlet Hose Replacement»(ref-338194-S20142823822009081700000)

Loss of Coolant (LC3)

Loss of Coolant (LH2, LY7, LLT)

Tools Required

J 24731 Tempilstick. See Special Tools .

The coolant thermostat can be tested using a temperature (tempil) stick. The temperature stick is a pencil like device. It has a wax material containing certain chemicals which melt at a given temperature. Temperature sticks can be used to determine a thermostat operating range, by rubbing 87°C (188°F) and 97°C (206°F) sticks on the outlet coolant pipe, located between the thermostat housing and the inlet radiator hose.

1. Use a tempilstick in order to find the opening and the closing temperatures of the coolant thermostat. J 24731-188 tempilstick melts at 87°C (188°F). The thermostat should begin to open at 90°C (194°F). J 24731-206 tempilstick melts at 97°C (206°F). The thermostat should be fully open at 107°C (225°F).
2. Replace the coolant thermostat if it does not operate properly between this temperature range.

Electrical Information Reference

1. «Circuit Testing»(ref-338151-S30248766082009081700000)
2. «Connector Repairs»(ref-338151-S41110648952009081700000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-338151-S41477264612009081700000)
4. «Wiring Repairs»(ref-338151-S09708660722009081700000)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Coolant Heater Replacement (LY7, KO5, LLT)»(ref-338194-S20910269562009081700000) or «Coolant Heater Replacement (LC3 (K05))»(ref-338194-S28619211672009081700000) or «Coolant Heater Replacement (LH2, KA3)»(ref-338194-S10812849202009081700000) or «Coolant Heater Replacement (LH2, KO5)»(ref-338194-S41131732972009081700000)
2. «Coolant Heater Cord Replacement (LY7, KO5)»(ref-338194-S09034645222009081700000) or «Coolant Heater Cord Replacement (LC3)»(ref-338194-S38213489732009081700000) or «Coolant Heater Cord Replacement (LH2, K05, KA3)»(ref-338194-S04278777172009081700000) or «Coolant Heater Cord Replacement (V6)»(ref-338194-S36598834432009081700000)

Vac N Fill Procedure

1. Install the J 42401 onto the coolant surge tank. See «Special Tools»(ref-338194-S08548216942009081700000) .
2. Attach the Vac N Fill cap to the J 42401 . See «Special Tools»(ref-338194-S08548216942009081700000) .
3. Attach the vacuum gage assembly to the Vac N Fill cap.
4. Attach the fill hose to the barb fitting on the vacuum gage 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 gage assembly and the vacuum tank.
11. Open the valve on the venturi assembly. The vacuum gage 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 gage 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 (LC3)»(ref-338194-S04917575742009081700000) or «Loss of Coolant (LH2, LY7, LLT)»(ref-338194-S31105212702009081700000) .
17. Open the valve on the vacuum gage assembly. The vacuum gage will drop as coolant is drawn into the system.
18. Once the vacuum gage reaches zero, close the valve on the vacuum gage assembly and repeat steps 11-17.
19. Detach the Vac N Fill cap from the J 42401 . See «Special Tools»(ref-338194-S08548216942009081700000) .
20. Remove the J 42401 from the coolant surge tank. See «Special Tools»(ref-338194-S08548216942009081700000) .
21. Add coolant to the system as necessary.
22. Inspect the concentration of the coolant mixture using J 26568 . See «Special Tools»(ref-338194-S08548216942009081700000) .
23. Detach the vacuum hose from the vacuum gage 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.

Fill Procedure

1. Close the radiator drain cock.
2. Install the air deflector. Refer to «Front Air Deflector Replacement»(ref-338114-S23457007412009081700000) .
3. Lower the vehicle.
4. Slowly add a mixture of 50/50 DEX-COOL antifreeze and clean drinkable water to the cooling system through the top of the surge tank opening. Refer to «Approximate Fluid Capacities»(ref-338171-S13883793012009081700000) .
5. Slowly fill the cooling system until the coolant stabilizes at 25 mm (1 inch) above the FULL COLD mark on the surge tank.
6. Install the surge tank cap.
7. Start the engine.
8. Run the engine at 2,000-2,500 RPM until the engine reaches normal operating temperature.
9. Allow the engine to idle for 3 minutes.
10. Shut the engine OFF.
11. Allow the engine to cool.
12. Add or remove coolant as necessary from the surge tank until the level is stabilized at the FULL COLD mark.
13. Inspect the cooling system for leaks.
14. Using J 26568 inspect the concentration of the engine coolant. See «Special Tools»(ref-338194-S08548216942009081700000) .

Filling Procedure

1. Loosen the charge air coolant radiator vent plug.
2. Place a shop towel around the charge air coolant radiator vent plug to absorb any leakage.
3. Using a small funnel, slowly fill the charge air cooling system through the charge air coolant cap port with a 50/50 coolant mixture until coolant is present at the charge air coolant radiator vent plug.
4. Hand tighten the charge air coolant radiator vent plug.
5. Using a small funnel, continue to slowly fill the charge air cooling system through the charge air coolant cap port until coolant is level with the charge air coolant cap port.
6. Install the charge air coolant cap.
7. Install the charge air coolant cap bolts and tighten to 10 N.m (89 lb in).
8. Slowly fill the charge air cooling system through the charge air coolant fill neck until coolant reaches the COLD FILL mark.
9. Cycle the charge air cooling pump ON and continue to slowly fill through the charge air coolant fill neck until the level stabilizes at the COLD FILL mark.
10. Slowly loosen the charge air coolant radiator vent plug until coolant is present.
11. Remove the shop towel from around the vent port.
12. Tighten the charge air coolant radiator vent plug to 10 N.m (89 lb in).
13. Continue to slowly fill through the charge air coolant fill neck until the level has stabilized at the COLD FILL mark.
14. Cycle the charge air coolant pump OFF.
15. Remove the charge air coolant cap bolts.
16. Remove the charge air coolant cap.
17. Ensure that coolant is almost level with the coolant cap fill port. Top off with the 50/50 coolant mixture through the charge air coolant cap port, if necessary.
18. Install the charge air coolant cap.
19. Install the charge air coolant cap bolts and tighten to 10 N.m (89 lb in).
20. Cycle the charge air coolant pump ON for 3 minutes.
21. Cycle the charge air coolant pump OFF.
22. Fill through the charge air coolant fill neck until the level stabilizes at the COLD FILL mark.
23. Repeat steps 19-21 until level is stabilized at the COLD FILL mark with the charge air coolant pump in the OFF position.
24. Inspect the concentration of the engine coolant, using the J 26568 . See «Special Tools»(ref-338194-S08548216942009081700000) .
25. Install the charge air cooling system pressure cap.
26. Inspect the charge air cooling system for leaks.

Radiator Cleaning (Charge Air Cooling)

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

Radiator Cleaning (Powertrain)

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

J 38185 Hose Clamp Pliers. See Special Tools .

J 38185 Hose Clamp Pliers. See Special Tools .

J 38185 Hose Clamp Pliers. See Special Tools .

J 38185 Hose Clamp Pliers. See Special Tools .

J 38185 Hose Clamp Pliers. See Special Tools .

J 38185 Hose Clamp Pliers. See Special Tools .

DT-47731 Transmission Cooler Quick Disconnect

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 (S/P) configuration that allows the engine control module (ECM) to operate both fans 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 their 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 approximately 104.25°C (220°F).
2. A/C refrigerant pressure exceeds approximately 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.

Cooling Fan Control - Three Fan System

The engine cooling fan system consists of a mechanical fan, 2 electrical pusher-type cooling fans, and 3 fan relays. The low speed, high speed, and series parallel (S/P) relays are arranged in an S/P configuration that allows the engine control module (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 their 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 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 4 minutes, regardless of coolant temperature.

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

1. Engine coolant temperature exceeds approximately 104.25°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 above 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 will be displayed if coolant temperature is above 117°C (243°F). For imports 115°C (239°F).
2. Engine coolant hot-Idle engine will be displayed if coolant temperature is above 118°C (245°F).
3. Engine overheated-Stop engine will be displayed if coolant temperature is above 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, it will send a class 2 message to the radio requesting display of the low coolant level message. There is approximately a 10 second delay before the HVAC control module sends a 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 maintains an efficient engine operating temperature during all engine speeds and operating conditions. The cooling system removes 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, allowing 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 bypasses the radiator, and the pump draws 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 and 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, absorbing additional heat.

Coolant is also directed to the throttle body. There the coolant circulates through passages in the casting. During initial start up, the coolant assists in warming the throttle body. 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 4 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 de-aeration 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, consisting of a core and 2 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 the radiator. The fins on the core absorb heat from the coolant passing through the tubes. Air passing between the fins 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 seals and pressurizes the cooling system. The cap contains a blow off or pressure valve and a vacuum or atmospheric valve. The pressure valve is held against the valve seat by a spring which protects the radiator by relieving pressure exceeding 15 psi. The vacuum valve is held against the valve seat by a spring which permits opening of the valve to relieve vacuum created in the cooling system during cooling. 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 rises 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 mounted pressure cap. 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, because 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 which 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 - V09

The transmission oil cooler (TOC) is an oil-to-water heat exchanger located in the radiator end tank and is non-serviceable. The transmission oil temperature is regulated by the temperature of the coolant leaving the radiator. The oil out of the transmission is plumbed through the TOC lines to the radiator end tank cooler then directed back to the transmission.

Transmission Oil Cooler - V03/V92

The transmission oil cooler (TOC) is an oil-to-air heat exchanger located between the radiator and the A/C condenser. The transmission oil temperature is regulated by the airflow passing over this heat exchanger. The oil out of the transmission is plumbed through the TOC lines to the cooler then directed back to the transmission. This cooler helps provided additional cooling for performance driving conditions.

Transmission Oil Cooler Lines

The transmission oil cooler (TOC) lines use quick connect fittings that must be removed using a special tool. The oil out of the transmission is pumped at a high pressure through the TOC lines to the heat exchanger and then directed back to the transmission.

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.