Cooling Fan - Right (10 Series)
| Connector Part Information OEM: 15454358 Service: 88987983 Description: 2-Way F GT 630 Series (BK) |
|---|
| Terminal Part Information Terminal/Tray: 15455571/23 Core/Insulation Crimp: F/3 Release Tool/Test Probe: 15315247/J-35616-42 (RD) |
Cooling Fan - Right (10 Series) Connector & Terminal Parts Information
| Pin | Wire Color | Circuit No. | Function |
|---|---|---|---|
| A | BK | 250 | Ground |
| B | L-BU | 409 | Cooling Fan Motor Supply Voltage |
Cooling Fan - Right (10 Series) Terminal Identification
Starter/Generator Control Module Coolant Pump (HP2)
| Connector Part Information OEM: 12131678 Service: 89046833 Description: 2-Way F Sealed (BK) |
|---|
| Terminal Part Information Terminal/Tray: 12177068/8 Core/Insulation Crimp: C/A Release Tool/Test Probe: 12093647/J-35616-4A (PU) |
Starter/Generator Control Module Coolant Pump (HP2) Connector & Terminal Parts Information
| Pin | Wire Color | Circuit No. | Function |
|---|---|---|---|
| 1 | BK | 150 | Ground |
| 2 | L-BU | 703 | Ignition 1 Voltage |
Starter/Generator Control Module Coolant Pump (HP2) Terminal Identification
Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .
Engine Overheated Indicator Always On
| Step | Action | Yes | No |
|---|---|---|---|
| Connector End View Reference: Engine Cooling Schematics DEFINITION: One of the following engine coolant temperature indicators is always On: Engine Coolant, Engine Coolant Hot/Idle Engine, Engine Hot-AC Off, Engine Overheated/Stop Engine. | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Start the engine. Does the engine coolant temperature indicator illuminate? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections |
| 3 | Install a scan tool. With the scan tool, observe the engine coolant temperature parameter in the powertrain control module (PCM) data list. Does the scan tool indicate that the coolant temperature is within the temperature range shown on the temperature gage? | Go to Engine Overheating | Go to Step 4 |
| 4 | Replace the instrument panel cluster (IPC). Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 5 | |
| 5 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
Engine Overheated Indicator Always On
Engine Coolant Temperature Indicator Always On
| Step | Action | Yes | No |
|---|---|---|---|
| Connector End View Reference: Cooling System Connector End Views DEFINITION: One of the following engine coolant temperature indicators is always On: Engine Coolant, Engine Coolant Hot/Idle Engine, Engine Hot-AC Off, Engine Overheated/Stop Engine. | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Start the engine. Does the engine coolant temperature indicator illuminate? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections |
| 3 | Install a scan tool. With the scan tool, observe the engine coolant temperature parameter in the powertrain control module (PCM) data list. Does the scan tool indicate that the coolant temperature is within the temperature range shown on the temperature gage? | Go to Engine Overheating | Go to Step 4 |
| 4 | Replace the instrument panel cluster (IPC). Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 5 | |
| 5 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
Engine Coolant Temperature Indicator Always On
Reference Information
Schematic Reference
Engine Cooling Schematics
Connector End View Reference
Cooling System Connector End Views
Description and Operation
Cooling System Description and Operation
Electrical Information Reference
- «Circuit Testing»(ref-277884-S17422072462008012100000)
- «Connector Repairs»(ref-277884-S12371167392008012100000)
- «Testing for Intermittent Conditions and Poor Connections»(ref-277884-S20700666652008012100000)
- «Wiring Repairs»(ref-277884-S08861102212008012100000)
Scan Tool Reference
Scan Tool Output Controls
Circuit/System Verification
The low coolant indicator should be OFF with the engine coolant at the proper level.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- «Surge Tank Replacement»(ref-277850-S24171617972008012100000)
- «Control Module References»(ref-277885-S04826892822008012100000)
- «Instrument Cluster Replacement»(ref-277858-S04786189312008012100000)
Repair Verification
Verify that the low coolant indicator is OFF with the engine coolant at the proper level.
Cooling Fan Always On
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Engine Cooling Schematics Connector End View Reference: Cooling System Connector End Views DEFINITION: One or both engine cooling fan motors run continuously in high or low speed. | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Turn ON the ignition, with the engine OFF. Are both cooling fans operating at low speed? | Go to Step 4 | Go to Step 3 |
| 3 | Is the left cooling fan operating at high speed? | Go to Step 5 | Go to Testing for Intermittent Conditions and Poor Connections |
| 4 | Remove the low speed fan relay. Did the fans turn OFF? | Go to Step 8 | Go to Step 6 |
| 5 | Remove the high speed fan relay. Did the left cooling fan turn OFF? | Go to Step 9 | Go to Step 7 |
| 6 | Repair the cooling fan motor supply voltage circuit of the right cooling fan for a short to voltage. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 12 | |
| 7 | Repair the cooling fan motor supply voltage circuit of the left cooling fan for a short to voltage. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 12 | |
| 8 | Inspect for poor connections at the low speed fan relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 10 |
| 9 | Inspect for poor connections at the high speed fan relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 11 |
| 10 | Replace the low speed fan relay. Did you complete the replacement? | Go to Step 12 | |
| 11 | Replace the high speed fan relay. Did you complete the replacement? | Go to Step 12 | |
| 12 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
Cooling Fan Always On
Electrical Information Reference
- «Circuit Testing»(ref-277884-S17422072462008012100000)
- «Connector Repairs»(ref-277884-S12371167392008012100000)
- «Testing for Intermittent Conditions and Poor Connections»(ref-277884-S20700666652008012100000)
- «Wiring Repairs»(ref-277884-S08861102212008012100000)
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- «Coolant Heater Replacement (4.8L, 5.3L (except RPO L33), 6.0L)»(ref-277850-S41580685552008012100000) or «Coolant Heater Replacement (5.3L (w/RPO L33))»(ref-277850-S18608246242008012100000) or «Coolant Heater Replacement (6.6L)»(ref-277850-S22991507882008012100000) or «Coolant Heater Replacement (8.1L)»(ref-277850-S03178784742008012100000) or «Coolant Heater Replacement (4.3L)»(ref-277850-S04607998592008012100000)
- «Coolant Heater Cord Replacement (4.8L, 5.3L (except RPO L33), 6.0L)»(ref-277850-S01965757542008012100000) or «Coolant Heater Cord Replacement (5.3L (w/RPO L33))»(ref-277850-S27953195852008012100000)
Engine Overheating
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Inspect the coolant level. Is the coolant level low? | Go to Step 11 | Go to Step 2 |
| 2 | Inspect the exhaust system for the following conditions: Damaged exhaust pipe Plugged catalytic converter Did you find and correct the condition? | Go to Step 22 | Go to Step 3 |
| 3 | Inspect for a loose drive belt. Is the drive belt loose? | Go to Step 4 | Go to Step 5 |
| 4 | Replace the drive belt. Refer to the appropriate procedure: Drive Belt Replacement for the 4.3L engine Drive Belt Replacement - Accessory (4.8L, 5.3L, and 6.0L Engines) or Drive Belt Replacement - Accessory (5.3L Engine w/RPO HP2) Drive Belt Replacement for the 6.6L (LLY) engine Drive Belt Replacement - Accessory for the 8.1L engine Was the repair complete? | Go to Step 22 | |
| 5 | Inspect for obstructed radiator air flow. If equipped with a 6.6L diesel, also inspect for an obstructed charged air cooler or debris between the radiator and air cooler. Is the radiator air flow obstructed? | Go to Step 6 | Go to Step 7 |
| 6 | Clean the radiator. Refer to Radiator Cleaning . Was the repair complete? | Go to Step 22 | |
| 7 | Inspect for an inoperative fan clutch. Refer to Fan Clutch Diagnosis . Is the fan clutch operating correctly? | Go to Step 9 | Go to Step 8 |
| 8 | Replace the fan clutch. Refer to Fan Clutch Replacement (Diesel) or Fan Clutch Replacement (Gasoline) . Was the repair complete? | Go to Step 22 | |
| 9 | Inspect the thermostat. Refer to Thermostat Diagnosis . Is the thermostat stuck in the closed position? | Go to Step 10 | Go to Step 15 |
| 10 | Replace the thermostat. Refer to Thermostat Replacement (4.3L Engine) or Thermostat Replacement (6.6L Engine) or Thermostat Replacement (8.1L Engine) . Was the repair complete? | Go to Step 22 | |
| 11 | Fill the coolant to the specified level. Perform a pressure test on the cooling system. Inspect for external coolant leaks. Are there any external leaks? | Go to Step 21 | Go to Step 12 |
| 12 | Perform a pressure test on the radiator cap. Does the radiator cap hold pressure? | Go to Step 14 | Go to Step 13 |
| 13 | Replace the radiator cap. Was the repair complete? | Go to Step 22 | |
| 14 | Inspect for combustion chamber gases leaking in the cooling system. Are bubbles present in the coolant? | Go to Step 19 | Go to Step 15 |
| 15 | Inspect for a inoperative water pump. Is the water pump inoperative? | Go to Step 16 | Go to Step 17 |
| 16 | Replace the water pump. Refer to Water Pump Replacement (4.3L) or Water Pump Replacement (4.8L, 5.3L, and 6.0L) or Water Pump Replacement (8.1L) or Water Pump Replacement (6.6L) . Was the repair complete? | Go to Step 22 | |
| 17 | Inspect for a blockage in the engine block coolant passages. Are the engine block coolant passages blocked? | Go to Step 18 | |
| 18 | Perform the cooling system flush. Refer to Flushing . Was the repair complete? | Go to Step 22 | |
| 19 | Check the engine oil. Is the engine oil foamy and/or milky? | Go to Step 20 | |
| 20 | Remove the cylinder head. Refer to the appropriate procedure: Cylinder Head Replacement - Left Side or Cylinder Head Replacement - Right Side for the 4.3L engine Cylinder Head Replacement - Left Side or Cylinder Head Replacement - Right Side for the 4.8L, 5.3L and 6.0L engine Cylinder Head Replacement - Left Side or Cylinder Head Replacement - Right Side for the 6.6L (LLY) engine Cylinder Head Replacement - Left Side or Cylinder Head Replacement - Right Side for the 8.1L engine If equipped with a 8.1L engine, inspect the head gasket for correct installation. Refer to Cylinder Head Replacement - Left Side or Cylinder Head Replacement - Right Side for the 8.1L engine Inspect the cylinder head and block for cracks. Was a damaged/faulty component found? | Go to Step 21 | |
| 21 | Replace and/or repair the component as necessary. Was the repair complete? | Go to Step 22 | |
| 22 | Fill the cooling system to the proper level, if necessary. Operate the engine. Does the engine overheat? | Go to Step 2 | System OK |
Engine Overheating
Loss of Coolant
| Step | Action | Yes | No |
|---|---|---|---|
| DEFINITION: The cooling system is losing coolant either internally or externally. | |||
| 1 | Were you sent here from Symptoms, or another diagnostic table? | Go to Step 2 | Go to Symptoms - Engine Cooling |
| 2 | Repair any present DTCs. Refer to Diagnostic System Check - Vehicle . Is the action complete? | Go to Step 3 | |
| 3 | Inspect the coolant level. Is the coolant at the proper level? | Go to Step 5 | Go to Step 4 |
| 4 | Fill the cooling system to the proper level. Refer to Draining and Filling Cooling System (Static Fill) or Draining and Filling Cooling System (w/RPO HP2) or Draining and Filling Cooling System (Vac-N-Fill) . Is the action complete? | Go to Step 5 | |
| 5 | Engine overheating can cause a loss of coolant. Is the engine overheating? | Go to Step 19 | Go to Step 6 |
| 6 | Idle the engine at normal operating temperature. Inspect for heavy white smoke coming out of the exhaust pipe. Is a heavy white smoke present from the exhaust pipe? | Go to Step 7 | Go to Step 8 |
| 7 | Coolant in the exhaust system creates a distinctive, burning coolant odor in the exhaust. Condensation in the exhaust system can cause an odorless white smoke during engine warm up. Does the white smoke have a burning coolant type odor? | Go to Step 20 | Go to Step 8 |
| 8 | Visually inspect the hoses, pipes and hose clamps. Are any of the hoses, clamps or pipes leaking? | Go to Step 21 | Go to Step 9 |
| 9 | Visually inspect the following components: Block heater Coolant pressure cap Core plugs Throttle body Engine block Intake manifold Radiator Thermostat housing Water pump Are any of the listed components leaking? | Go to Step 21 | Go to Step 10 |
| 10 | Pressure test the cooling system. Refer to Cooling System Leak Testing . With the cooling system pressurized, visually inspect the components listed in steps 7 and 8. Are any leaks present? | Go to Step 21 | Go to Step 11 |
| 11 | Pressure test the coolant pressure cap. Refer to Pressure Cap Testing . Does the coolant pressure cap hold pressure? | Go to Step 12 | Go to Step 16 |
| 12 | Inspect for the following conditions: A coolant smell inside of the vehicle Coolant in the HVAC module drain tube Coolant on the vehicle floor covering near the HVAC module Is coolant present? | Go to Step 21 | Go to Step 13 |
| 13 | Inspect the underside of the engine oil fill cap for a gray/white milky substance. Is there a milky substance under the oil fill cap? | Go to Step 14 | Go to Step 15 |
| 14 | Inspect the engine oil fluid level indicator for a gray/white milky substance. Is there a milky substance on the engine oil fluid level indicator? | Go to Step 17 | Go to Step 15 |
| 15 | Inspect the automatic transmission oil fluid level indicator, if equipped, for a gray/white milky substance. Is there a milky substance on the automatic transmission fluid level indicator? | Go to Step 18 | Go to Step 22 |
| 16 | Replace the coolant pressure cap. Is the repair complete? | Go to Step 22 | |
| 17 | Replace the radiator. Refer to Radiator Replacement (4.3, 4.8, 5.3, and 6.0L) or Radiator Replacement (8.1L) or Radiator Replacement (Diesel) . Service the engine oil and filter. Refer to one of the following procedures: Engine Oil and Oil Filter Replacement for the 4.3L engine Engine Oil and Oil Filter Replacement for the 4.8L, 5.3L, and 6.0L engine Engine Oil and Oil Filter Replacement for the 6.6L (LLY) engine Engine Oil and Oil Filter Replacement for the 8.1L engine Is the repair complete? | Go to Step 22 | |
| 18 | Replace the radiator. Refer to Radiator Replacement (4.3, 4.8, 5.3, and 6.0L) or Radiator Replacement (8.1L) or Radiator Replacement (Diesel) . Service the automatic transmission. Refer to one of the following procedures: Engine Coolant/Water in Transmission for the 4L60-E/4L65-E transmission Engine Coolant/Water in Transmission for the 4L80-E/4L85-E transmission Is the repair complete? | Go to Step 22 | |
| 19 | Repair the engine overheating condition. Refer to Engine Overheating . Is the repair complete? | Go to Step 22 | |
| 20 | Repair the engine internal coolant leak. Refer to one of the following procedures: Coolant in Combustion Chamber or Coolant in Engine Oil for the 4.3L engine Coolant in Combustion Chamber or Coolant in Engine Oil for the 4.8L, 5.3L, and 6.0L enigne Coolant in Combustion Chamber or Coolant in Engine Oil for the 6.6L (LLY) engine Coolant in Combustion Chamber or Coolant in Engine Oil for the 8.1L engine Is the repair complete? | Go to Step 22 | |
| 21 | Repair or replace the leaking component. Refer to the appropriate repair. Is the repair complete? | Go to Step 22 | |
| 22 | Operate the system in order to verify the repair. Did you find and correct the condition? | System OK | Go to Step 2 |
Loss of Coolant
Tools Required
J 24731 Tempil Stick. See Special Tools .
Use one of the following procedures in testing for a malfunctioning thermostat.
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- «Coolant Heater Replacement (4.8L, 5.3L (except RPO L33), 6.0L)»(ref-277850-S41580685552008012100000) or «Coolant Heater Replacement (5.3L (w/RPO L33))»(ref-277850-S18608246242008012100000) or «Coolant Heater Replacement (6.6L)»(ref-277850-S22991507882008012100000) or «Coolant Heater Replacement (8.1L)»(ref-277850-S03178784742008012100000) or «Coolant Heater Replacement (4.3L)»(ref-277850-S04607998592008012100000)
- «Coolant Heater Cord Replacement (4.8L, 5.3L (except RPO L33), 6.0L)»(ref-277850-S01965757542008012100000) or «Coolant Heater Cord Replacement (5.3L (w/RPO L33))»(ref-277850-S27953195852008012100000)
Electrical Information Reference
- «Circuit Testing»(ref-277884-S17422072462008012100000)
- «Connector Repairs»(ref-277884-S12371167392008012100000)
- «Testing for Intermittent Conditions and Poor Connections»(ref-277884-S20700666652008012100000)
- «Wiring Repairs»(ref-277884-S08861102212008012100000)
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- «Coolant Heater Replacement (4.8L, 5.3L (except RPO L33), 6.0L)»(ref-277850-S41580685552008012100000) or «Coolant Heater Replacement (5.3L (w/RPO L33))»(ref-277850-S18608246242008012100000) or «Coolant Heater Replacement (6.6L)»(ref-277850-S22991507882008012100000) or «Coolant Heater Replacement (8.1L)»(ref-277850-S03178784742008012100000) or «Coolant Heater Replacement (4.3L)»(ref-277850-S04607998592008012100000)
- «Coolant Heater Cord Replacement (4.8L, 5.3L (except RPO L33), 6.0L)»(ref-277850-S01965757542008012100000) or «Coolant Heater Cord Replacement (5.3L (w/RPO L33))»(ref-277850-S27953195852008012100000)
Engine Fails To Reach Normal Operating Temperature
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Did you review the Symptoms-Engine Cooling diagnostic information and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Engine Cooling |
| 2 | Verify that the engine does not reach normal operating temperature. Does the engine reach normal operating temperature? | System OK | Go to Step 3 |
| 3 | Inspect the coolant level. Is the coolant level below the add mark? | Go to Step 4 | Go to Step 5 |
| 4 | Add coolant as necessary. Perform a cooling system pressure test. Does the cooling system hold pressure? | System OK | Go to Step 5 |
| 5 | Inspect for a stuck open, missing, or incorrect thermostat. Refer to Thermostat Diagnosis . Is the thermostat operating properly? | Go to Step 6 | Go to Step 8 |
| 6 | Is the vehicle equipped with a 6.6 L diesel engine? | Go to Step 7 | Go to Step 8 |
| 7 | Inspect for a faulty turbocharger coolant bypass valve Is the turbocharger coolant bypass valve functioning properly? | Go to Step 9 | |
| 8 | Install the correct replacement thermostat. Refer to Thermostat Replacement (4.3L Engine) or Thermostat Replacement (6.6L Engine) or Thermostat Replacement (8.1L Engine) . Is the repair complete? | Go to Step 10 | |
| 9 | Install a new turbocharger coolant bypass valve. Refer to Turbocharger Coolant Bypass Valve Replacement (6.6L Engine) . Is the repair complete? | Go to Step 10 | |
| 10 | Run the engine in order to verify the repair. Does the engine fail to reach normal operating temperature? | System OK |
Engine Fails To Reach Normal Operating Temperature
Filling Procedure
- Install the lower radiator hose to the radiator.
- Using the J 38185 reposition the lower radiator hose clamp. See «Special Tools»(ref-277850-S19943780362008012100000) .
- If the left and right engine block coolant drain plugs were removed, perform the following. Apply pipe sealer to the drain plugs. NOTE: Refer to «Fastener Notice»(ref-277849-S30907907212008012100000) . Install the drain plugs. Tighten: Tighten the drain plugs to 60 N.m (44 lb ft).
- Install the engine block coolant heater, if equipped. Refer to «Coolant Heater Replacement (4.8L, 5.3L (except RPO L33), 6.0L)»(ref-277850-S41580685552008012100000) or «Coolant Heater Replacement (5.3L (w/RPO L33))»(ref-277850-S18608246242008012100000) or «Coolant Heater Replacement (6.6L)»(ref-277850-S22991507882008012100000) or «Coolant Heater Replacement (8.1L)»(ref-277850-S03178784742008012100000) or «Coolant Heater Replacement (4.3L)»(ref-277850-S04607998592008012100000) .
- Lower the vehicle.
- Open the cooling system bleeder screws, if equipped.
- Slowly fill the cooling system with a 50/50 coolant mixture. Refer to «Approximate Fluid Capacities»(ref-277950-S03550976542008012100000) .
- Close the cooling system bleeder screws, if equipped.
- Install the coolant pressure cap.
- Start the engine.
- Run the engine at 2,000-2,500 RPM until the engine reaches normal operating temperature.
- Allow the engine to idle for 3 minutes.
- Shut the engine OFF.
- Allow the engine to cool.
- Top off the coolant as necessary.
- Inspect the concentration of the engine coolant using the J 26568 . See «Special Tools»(ref-277850-S19943780362008012100000) .
- Rinse away any excess coolant from the engine and the engine compartment.
- Install the lower radiator hose to the radiator.
- Using the J 38185 reposition the lower radiator hose clamp. See «Special Tools»(ref-277850-S19943780362008012100000) .
- If the left and right engine block coolant drain plugs were removed, perform the following. Apply pipe sealer to the drain plugs. Install the drain plugs. Tighten: Tighten the drain plugs to 60 N.m (44 lb ft).
- Install the engine block coolant heater, if equipped. Refer to «Coolant Heater Replacement (4.8L, 5.3L (except RPO L33), 6.0L)»(ref-277850-S41580685552008012100000) or «Coolant Heater Replacement (5.3L (w/RPO L33))»(ref-277850-S18608246242008012100000) or «Coolant Heater Replacement (6.6L)»(ref-277850-S22991507882008012100000) or «Coolant Heater Replacement (8.1L)»(ref-277850-S03178784742008012100000) or «Coolant Heater Replacement (4.3L)»(ref-277850-S04607998592008012100000) .
- Lower the vehicle.
- Open the cooling system bleeder screws, if applicable.
- Slowly fill the cooling system with a 50/50 coolant mixture. Refer to «Approximate Fluid Capacities»(ref-277950-S03550976542008012100000) .
- Close the cooling system bleeder screws, if applicable.
- Install the coolant pressure cap.
- Start the engine.
- Run the engine at 2,000-2,500 RPM until the engine reaches normal operating temperature.
- Allow the engine to idle for 3 minutes.
- Perform the following step 4 times: Run the engine at 4,000 RPM for 30 seconds. Allow the engine to return to idle for 30 seconds.
- Shut the engine OFF.
- Allow the engine to cool.
- Top off the coolant as necessary.
- Inspect the concentration of the engine coolant using the J 26568 . See «Special Tools»(ref-277850-S19943780362008012100000) .
- Rinse away any excess coolant from the engine and the engine compartment.
Radiator Cleaning
| CAUTION | NEVER spray water on a hot radiator. The resulting steam could cause personal injury. |
Note. The radiator fins are necessary for good heat transfer. Do not brush the fins. This may cause damage to the fins, reducing heat transfer.
- Some conditions may require the use of warm water and a mild detergent.
- Clean the A/C condenser fins.
- Clean between the A/C condenser and radiator.
- Clean the radiator cooling fins.
- Straighten any damaged cooling fins.
- Vehicles equipped with a diesel engine, clean between the charged air cooler and the A/C condenser also. Removal of the charge air cooler may be necessary to clean the fins. Refer to «Charged Air Cooler Replacement»(ref-277954-S32587452082008012100000) .
J 43181 Heater Line Quick Connect Release Tool. See Special Tools .
J 41240-5A Fan Clutch Wrench
J 46406 Fan Clutch Remover and Installer. See Special Tools .
J 41240-5A Fan Clutch Wrench
J 46406 Fan Clutch Remover and Installer. See Special Tools .
J 41240 Fan Clutch Remover and Installer. See Special Tools .
Cooling Fan Control - Two Fan System
The engine cooling fan system consists of 2 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 receive positive voltage from the cooling fan relays which receive battery positive voltage from the underhood fuse block. The fan relay coils receive ignition 1 voltage from the powertrain relay.
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 series/parallel 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. The ECM grounds the high speed fan relay and the cooling fan series/parallel relay through the high speed cooling fan relay control circuit. This energizes the cooling fan control 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.
Schematic Reference
Engine Cooling Schematics
Engine Coolant Indicators
ENGINE COOLANT HOT
The instrument panel cluster (IPC) displays ENGINE COOLANT HOT message when the IPC receives a class 2 message from the powertrain control module (PCM) requesting illumination of this driver warning.
ENGINE OVERHEATED
The IPC displays ENGINE OVERHEATED message when the IPC receives a class 2 message from the PCM requesting illumination of this driver warning.
LOW COOLANT LEVEL B
The IPC displays LOW COOLANT LEVEL message when the IPC receives a class 2 message from the PCM requesting illumination of this driver warning.
REDUCED ENGINE POWER
The IPC displays REDUCED ENGINE POWER message when the IPC detects a reduced engine power condition from the PCM. The IPC receives a class 2 message from the PCM requesting illumination when the engine temperature reaches 132°C (270°F).
The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) 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.
During low speed operation, the PCM 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 PCM 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 PCM 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.
| IMPORTANT | The right and left cooling fan connectors are interchangeable. When servicing the fans be sure that the connectors are plugged into the correct fan. |
The PCM commands the low speed cooling fans ON under the following conditions
- Engine coolant temperature exceeds approximately 104.25°C (220°F).
- A/C refrigerant pressure exceeds 1447 kPa (210 psi).
- 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 min. regardless of coolant temperature.
The PCM commands the high speed fans ON under the following conditions
- Engine coolant temperature exceeds approximately 107.2°C (220°F).
- A/C refrigerant pressure exceeds approximately 1824 kPa (265 psi).
- 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.
Coolant Level Control (If Equipped)
The engine cooling system contains an engine coolant level switch to alert the driver in the event of a coolant loss. The powertrain control module (PCM) sends out a coolant loss signal over the coolant level switch signal circuit. When the engine coolant level switch reads a low coolant level in the fill tank, the switch opens. The message center receives its power from engine wiring harness junction block on the battery positive voltage circuit. Ground is provided by the ground circuits via the body wiring harness junction block and the engine wiring harness junction block. The cluster receives the class 2 message from the PCM indicating Low Coolant and displays the LOW COOLANT LEVEL message on the driver information center (DIC).
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 -18°C (0°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.
Auxiliary Coolant Pump (w/HP2)
The auxiliary coolant pump circulates coolant through the engine and heater core when HVAC requires heating and the engine is HOT and OFF. The HCM will turn on the auxiliary coolant pump when the HVAC control module commands it to do so by sending a class 2 signal to the HCM.
The cooling system's function is to maintain an efficient engine operating temperature during all engine speeds and operating conditions. The cooling system is designed to remove approximately one-third of the heat produced by the burning of the air-fuel mixture. When the engine is cold, the coolant does not flow to the radiator until the thermostat opens. This allows the engine to warm quickly.
Cooling Cycle
Coolant is drawn from the radiator outlet and into the water pump inlet by the water pump. Coolant will then be pumped through the water pump outlet and into the engine block. In the engine block, the coolant circulates 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.
Some coolant is also pumped from the water pump to the heater core, then back to the water pump. This provides the passenger compartment with heat and defrost.
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 start up, the coolant assists in warming the throttle body. During normal operating temperatures, the coolant assists in regulating the throttle body temperature.
Cooling Cycle (6.6L Diesel Engine)
Coolant is drawn from the radiator outlet and into the water pump inlet by the water pump. The coolant flows to the heater core while the engine is running. This provides the passenger compartment with heat and defrost.
Coolant is then pumped through the water pump outlet and through the coolant pipe to the engine oil cooler. The coolant flows around the oil cooler element and to the rear engine cover. The rear engine cover distributes the coolant flow to both banks of 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 turbocharger. There it circulates through passages in the center housing. During engine warm-up cycle the bypass valve located in the turbocharger inlet hose at the outlet pipe prevents coolant flow. During normal operating temperatures, the coolant assists in keeping the turbocharger cool.
From the cylinder heads, the coolant flows to the thermostats. The coolant flows from the thermostat housing to the water pump through the bypass pipe until the enginereaches 85°C (185°F).
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 suitable drinking 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 tube and fin crossflow design that extends from the inlet tank to the outlet tank. Fins are placed around the outside of the tubes to improve heat transfer to the atmosphere.
The inlet and outlet tanks are a molded, high temperature, nylon reinforced plastic material. A high temperature rubber gasket seals the tank flange edge to the aluminum core. The tanks are clamped to the core with clinch tabs. The tabs are part of the aluminum header at each end of the core.
The radiator also has a drain cock located in the bottom of the left hand tank. The drain cock unit includes the drain cock and drain cock seal.
The radiator removes heat from the coolant passing through it. The fins on the core transfer heat from the coolant passing through the tubes. As air passes between the fins, it absorbs heat and cools the coolant.
Surge Tank
The surge tank is a plastic tank with a threaded 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 that allows the coolant to expand and contract. The surge tank provides a coolant fill point and a central air bleed location.
During vehicle use, the coolant heats and expands. The increased coolant volume flows into the surge tank. As the coolant circulates, any air is allowed to bubble out. Coolant without air bubbles absorbs heat much better than coolant with bubbles.
Pressure Cap
The pressure cap seals the cooling system. It contains a blow off or pressure relief valve and a vacuum or atmospheric valve. The pressure valve is held against its seat by a spring, which protects the radiator from excessive cooling system pressure. 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, might cause the radiator and/or coolant hoses to collapse.
The pressure cap allows cooling system pressure to build up as the temperature increases. As the pressure builds, the boiling point of the coolant increases. Engine coolant can be safely run at a temperature much higher than the boiling point of the coolant at atmospheric pressure. The hotter the coolant is, the faster the heat transfers from the radiator to the cooler, passing air.
The pressure in the cooling system can get too high. When the cooling system pressure exceeds the rating of the pressure cap, it raises the pressure valve, venting the excess pressure.
As 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 surge tank. This equalizes the pressure in the cooling system with atmospheric pressure, preventing the radiator and coolant hoses from collapsing.
Cooling Fan and Clutch
The engine cooling fan and clutch are driven by the crankshaft via the drive belt. The cooling fan draws air through the radiator to improve the transfer of heat from the coolant to the atmosphere. As the fan blades spin, they pull cool, outside air past the radiator core. The fan clutch drives the cooling fan. The fan clutch controls the amount of torque that is transmitted from the crankshaft to the fan blades. The clutch allows more torque to engage on the fan when the engine operating temperature increases and/or the vehicle speed is low. As the torque increases, the fan turns more quickly. The fan clutch decreases the torque applied to the cooling fan when the engine temperature decreases and/or the vehicle speed is high. As the torque decreases, the fan speed decreases.
Air Baffles and Seals
The cooling system uses deflectors, air baffles and air seals to increase cooling system capability. Deflectors are installed under the vehicle to redirect airflow beneath the vehicle and through the radiator to increase engine cooling. Air baffles are also used to direct airflow through the radiator and increase cooling capability. Air seals prevent air from bypassing the radiator and A/C condenser, and prevent recirculation of hot air for better hot weather cooling and A/C condenser performance.
Water Pump
The water pump is a centrifugal vane impeller type pump. The pump consists of a housing with coolant inlet and outlet passages and an impeller. The impeller is mounted on the pump shaft and consists of a series of flat or curved blades or vanes on a flat plate. 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.
Water Pump (6.6L Diesel Engine)
The water pump is a centrifugal vane impeller type pump. The water pump is gear driven by the crankshaft gear. The pump consists of a housing with coolant inlet and outlet passages and an impeller. The impeller is a flat plate mounted on the pump shaft with a series of flat or curved blades or vanes. When the impeller rotates, the coolant between the vanes is thrown outward by centrifugal force. The impeller shaft is supported by bearings. Splash of the engine oil lubricates the bearings. The bearings and shaft are sealed to prevent engine oil to mix with the coolant. If the seal fails, coolant will leak out the vent hole in the water pump housing.
The purpose of the water pump is to circulate coolant throughout the cooling system.
Thermostat
The thermostat is a coolant flow control component. It's purpose is to help regulate the operating temperature of the engine. It utilizes a temperature sensitive wax-pellet element. The element connects to a valve through a small piston. When the element is heated, it expands and exerts pressure against the small piston. 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. After the coolant temperature reaches the 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, 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.
Thermostats (6.6L Diesel Engine)
The thermostats are coolant flow control components. The purpose of the thermostats are to regulate the correct operating temperature of the engine. The thermostats 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 piston. This pressure forces the valve to open. As the element is cooled, it contracts. This contraction allows a spring to push the valve closed.
The 6.6L diesel engine requires two thermostats for correct coolant flow. The front thermostat is a dual purpose thermostat. The front thermostat controls the coolant flow to the bypass port and to the water outlet. The rear thermostat only controls the coolant flow to the water outlet.
When the coolant temperature is below the rated thermostat opening temperature, the front thermostat valve remains closed to the water outlet and is opened to the bypass port. The bottom portion of the thermostat is raised off of the bypass port while at the same time the top portion closes the coolant flow to the water outlet. The rear thermostat also is closed to the water outlet during engine warm-up. This prevents circulation of the coolant to the radiator and allows the engine to warm up quickly. After the coolant temperature reaches 82°C (180°F) the front thermostat primary valve opening temperature, the front thermostat primary valve will start to open. The coolant is then allowed to circulate through the thermostat to the radiator where the engine heat is dissipated to the atmosphere. As the engine coolant reaches 85°C (185°F) and more coolant demand is required the front thermostat secondary valve begins to close the bypass port and the rear thermostat begins to open coolant flow to the water outlet. The thermostats will continue to control the coolant flow by opening and closing. The front thermostat will be fully open when the coolant temperature reaches 95°C (203°F) the rear thermostat will be fully open when the coolant temperature reaches 100°C (212°F). The thermostat also provides a restriction in the cooling system, even after the 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 Cooler
The engine oil cooler is a heat exchanger. It is located inside the left side end tank of the radiator. The engine oil temperature is controlled by the temperature of the engine coolant that surrounds the oil cooler in the radiator.
The engine oil pump, pumps the oil through the engine oil cooler line to the oil cooler. The oil then flows through the cooler where the engine coolant absorbs heat from the oil. The oil is then pumped through the oil cooler return line, to the oil filter, to the engine block oil system.
Engine Oil Cooler (6.6L Diesel Engine)
The engine oil cooler is a heat exchanger. The engine oil cooler is mounted to the left lower corner of the engine. The oil filter is attached to the oil cooler housing. The engine coolant flows around the oil cooler element. The oil cooler element is a series of plates. The engine oil temperature is regulated by the temperature of the engine coolant that surrounds the oil cooler as the engine oil passes through the cooler.
The engine oil pump, pumps the oil through the engine oil feed line to the oil cooler. The oil then flows down through the cooler while the engine coolant absorbs heat from the oil. The oil is then pumped through the oil return line, to the oil filter, then to the main engine oil passage.
Transmission Oil Cooler
The transmission oil cooler is a heat exchanger. It is located inside the right side end tank of the radiator. The transmission fluid temperature is regulated by the temperature of the engine coolant in the radiator.
The transmission oil pump, pumps the fluid through the transmission oil cooler line to the transmission oil cooler. The fluid then flows through the cooler where the engine coolant absorbs heat from the fluid. The fluid is then pumped through the transmission oil cooler return line, to the transmission.
Turbocharger Bypass Valve (6.6L Diesel Engine)
The turbocharger bypass valve is a temperature control valve. The valve is located in the turbocharger coolant inlet hose at the water outlet tube.
The purpose of the valve is to close the coolant flow through the turbocharger. Closing off the coolant flow through the turbocharger avoids turbocharger overcooling.