Cooling Fan Control
The engine cooling fan system consists of 2 cooling fans and 3 relays. The relays are powered by the battery positive voltage circuit and controlled by a switched ground from the powertrain control module (PCM).
During low speed operation, the PCM supplies the ground path for the low speed cooling fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan low relay coil, closes the relay contacts, and supplies battery positive voltage from the COOL FAN LO fuse through the cooling fan motor supply voltage circuit to the cooling fan. During high speed operation the PCM supplies the ground path for the cooling fan low relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan high relay and the s/p cooling fan relay through the high speed fan relay control circuit.
The PCM commands the fan on under the following conditions
- Engine coolant temperature exceeds approximately 98°C (208°F) Low Fan Speed
- Engine coolant temperature exceeds approximately 102°C (216°F) High Fan Speed
- A/C refrigerant pressure exceeds 361 kPa (52 psi) Low Fan Speed
- A/C refrigerant pressure exceeds 2100 kPa (300 psi) High Fan Speed
- When the engine coolant temperature exceeds 112°C (234°F) at key off, the fan high speed will run for up to 300 seconds. If within that time frame 102°C (216°F) is reached then fan speed will change from high to low speed. If within that time frame 99°C (210°F) is reached then fan speed will change from low to off.
The PCM commands the fan off under the following conditions
- A/C is requested and engine speed exceeds 6,240 RPM
- Engine coolant temperature exceeds approximately 99°C (210°F) turns the cooling fans from low to off.
LOW COOLANT LEVEL
The IPC illuminates the low coolant warning indicator when any of the following occur
- The BCM detects a low coolant level condition for at least 30 seconds. The IPC receives a class 2 message from the BCM requesting illumination.
- The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.
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 power cord has a thermal element in the cord end that does not allow current to the heater until the ambient temperature reaches 0°F or -18°C.
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.
Charge Air Cooling System (LSJ Only)
The charge air cooling systems function is to reduce the temperature of the air charge that is heated during the supercharging process which improves the efficiency of the supercharging system. The charge air cooling system is a water-to-air system that uses a dedicated electric coolant pump, a modified intake manifold, and a separate charge air cooling radiator located between the condenser and the radiator to cool the air charge.
Cooling Cycle
Coolant flows from the radiator outlet and into the water pump inlet. Some coolant flows from the water pump, to the heater core, then back to the water pump. This provides the passenger compartment with heat and defrost capability as the coolant warms up.
Coolant also flows from the water pump outlet and into the engine block. In the engine block, the coolant circulates through the water jackets surrounding the cylinders where it absorbs heat.
The coolant then flows through the cylinder head gasket openings and into the cylinder heads. In the cylinder heads, the coolant flows through the water jackets surrounding the combustion chambers and valve seats, where it absorbs additional heat.
From the cylinder heads, the coolant flows to the thermostat. The flow of coolant will either be stopped at the thermostat until the engine reaches normal operating temperature, or it will flow through the thermostat and into the radiator where it is cooled. At this point, the coolant flow cycle is completed.
Efficient operation of the cooling system requires proper functioning of all cooling system components. The cooling system consists of the following components
Coolant
The engine coolant is a solution made up of a 50-50 mixture of 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 right 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.
Pressure Cap
The pressure cap seals 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, 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.
Surge Tank
The surge tank is a plastic tank that the pressure cap mounts onto. 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 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 timing chain.
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.
Transmission Oil Cooler
The transmission oil cooler is a heat exchanger. It is located inside the left 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.
Scheme 114
Scheme 115
Connector Part Information
OEM: 13517352
Service: 88988506
Description: 2-Way F GT 280 Sealed (BK)
Terminal Part Information
Terminal/Tray: 15304720/19
Core/Insulation Crimp: 4/5
Release Tool/Test Probe: 15315247/J-35616-4A (PU)
| Pin | Wire Color | Circuit No. | Function |
|---|---|---|---|
| A | L-BU | 409 | Cooling Fan Motor Supply Voltage |
| B | BK | 1250 | Ground |
CONNECTOR INFORMATION - COOLING FAN (LEFT)
Scheme 116
Connector Part Information
OEM: 13517352
Service: 88988506
Description: 2-Way F GT 280 Sealed (BK)
Terminal Part Information
Terminal/Tray: 15304720/19
Core/Insulation Crimp: 4/5
Release Tool/Test Probe: 15315247/J-35616-4A (PU)
| Pin | Wire Color | Circuit No. | Function |
|---|---|---|---|
| A | GY | 532 | Cooling Fan Motor Supply Voltage |
| B | WH | 504 | Cooling Fan Low Reference |
CONNECTOR INFORMATION - COOLING FAN (RIGHT)
Scheme 117
Cooling Fan Relay
| Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
| Operating Conditions: The engine is operating in closed loop Parameter Normal Operation: FC Relay xx Circuit Status with fans Off: Indeterminate | |||
| FC Relay 1 Circuit Status | Fault | Fault | Fault |
| FC Relay 2 and 3 Circuit Status | Fault | Fault | Fault |
SCAN TOOL DATA - COOLING FAN RELAY
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-268410-S02883852162007102300000)
- «CONNECTOR REPAIRS»(ref-268413-S16594189052007102300000)
- «TESTING FOR INTERMITTENT CONDITIONS AND POOR CONNECTIONS»(ref-268410-S06240382452007102300000)
- «WIRING REPAIRS»(ref-268410-S19177984692007102300000) ]
DTC Type Reference
POWERTRAIN DIAGNOSTIC TROUBLE CODE (DTC) TYPE DEFINITIONS
Scan Tool Reference
SCAN TOOL DATA LIST (3.6L) - ENGINE COOLING
SCAN TOOL DATA DEFINITIONS (3.6L) - ENGINE COOLING
SCAN TOOL OUTPUT CONTROLS (3.6L) - ENGINE COOLING
Circuit/System Verification
- Ignition ON, command the appropriate fan relay ON and OFF with a scan tool. You should hear or feel the relay click.
- If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.
Repair Instructions
Perform the DIAGNOSTIC REPAIR VERIFICATION - VEHICLE DIAGNOSTIC INFORMATION after completing the diagnostic procedure.
- «RELAY REPLACEMENT (WITHIN AN ELECTRICAL CENTER)»(ref-268410-S29225272442007102300000) and «RELAY REPLACEMENT (ATTACHED TO WIRE HARNESS)»(ref-268410-S20358609962007102300000)
- «CONTROL MODULE REFERENCES»(ref-268408-S27515093052007102300000) for ECM replacement, setup, and programming
Symptoms - Engine Cooling
Note. Review the system operation in order to familiarize yourself with the system functions. Refer to the following
COOLING SYSTEM DESCRIPTION AND OPERATION
Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to TESTING FOR INTERMITTENT CONDITIONS AND POOR CONNECTIONS .
Schematic Reference: ENGINE COOLING SCHEMATICS
Description and Operation: COOLING SYSTEM DESCRIPTION AND OPERATION
Connector End View Reference: COOLING SYSTEM CONNECTOR END VIEWS
Electrical Information Reference
- «CIRCUIT TESTING»(ref-268410-S02883852162007102300000)
- «CONNECTOR REPAIRS»(ref-268413-S16594189052007102300000)
- «TESTING FOR INTERMITTENT CONDITIONS AND POOR CONNECTIONS»(ref-268410-S06240382452007102300000)
- «WIRING REPAIRS»(ref-268410-S19177984692007102300000)
Scan Tool Reference
SCAN TOOL DATA LIST (3.6L) - ENGINE COOLING
SCAN TOOL DATA DEFINITIONS (3.6L) - ENGINE COOLING
SCAN TOOL OUTPUT CONTROLS (3.6L) - ENGINE COOLING
- 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 DIAGNOSTIC INFORMATION»(ref-268408-S33461162912007102300000) .
- Ignition ON, verify with a scan tool that the control module is not commanding the fan ON.
- Observe that the fans are not ON.
- If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions that the concern was detected.
Perform the DIAGNOSTIC REPAIR VERIFICATION - VEHICLE DIAGNOSTIC INFORMATION after completing the diagnostic procedure.
- «ENGINE COOLANT FAN MOTOR REPLACEMENT»(ref-268430-S06504247802007102300000)
- «RELAY REPLACEMENT (WITHIN AN ELECTRICAL CENTER)»(ref-268410-S29225272442007102300000) and «RELAY REPLACEMENT (ATTACHED TO WIRE HARNESS)»(ref-268410-S20358609962007102300000)
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-268410-S02883852162007102300000)
- «CONNECTOR REPAIRS»(ref-268413-S16594189052007102300000)
- «TESTING FOR INTERMITTENT CONDITIONS AND POOR CONNECTIONS»(ref-268410-S06240382452007102300000)
- «WIRING REPAIRS»(ref-268410-S19177984692007102300000)
Scan Tool Reference
SCAN TOOL DATA LIST (3.6L) - ENGINE COOLING
SCAN TOOL DATA DEFINITIONS (3.6L) - ENGINE COOLING
SCAN TOOL OUTPUT CONTROLS (3.6L) - ENGINE COOLING
- 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 DIAGNOSTIC INFORMATION»(ref-268408-S33461162912007102300000) .
- 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.
- If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions that the concern was detected.
Perform the DIAGNOSTIC REPAIR VERIFICATION - VEHICLE DIAGNOSTIC INFORMATION after completing the diagnostic procedure.
- «RELAY REPLACEMENT (WITHIN AN ELECTRICAL CENTER)»(ref-268410-S29225272442007102300000) and «RELAY REPLACEMENT (ATTACHED TO WIRE HARNESS)»(ref-268410-S20358609962007102300000)
- «ENGINE COOLANT FAN MOTOR REPLACEMENT»(ref-268430-S06504247802007102300000)
Engine Overheating
| Step | Action | Yes | No |
|---|---|---|---|
| DEFINITION: Either of the following conditions indicate a probable engine overheat condition. The engine temperature gage is in the red (overheat) zone and/or the engine temperature indicator is ON. Hot engine coolant overflows from the coolant recovery reservoir and/or radiator cap onto the ground while the engine is running. | |||
| 1 | Inspect and fill the cooling system, as necessary. Refer to DRAINING AND FILLING COOLING SYSTEM (LY7 GE 47716 FILL) and DRAINING AND FILLING COOLING SYSTEM (LY7 STATIC FILL) . Inspect the cooling system for leaks, as necessary. Repair the cooling system leaks, as necessary. Has the inspection/repair been performed? | Go to Step 2 | |
| 2 | Start the engine and allow the engine to run at approximately 1,200 RPM. Use the Scan Tool in order to verify the overheat condition. Does the Scan Tool verify the engine overheat condition? | Go to Step 3 | Go to DIAGNOSTIC SYSTEM CHECK - VEHICLE DIAGNOSTIC INFORMATION |
| 3 | Verify that the cooling fans are operating properly. Repair the cooling fan system, as necessary. Does the engine still overheat? | Go to Step 4 | System OK |
| 4 | Perform the following inspections: Inspect the radiator and the A/C condenser cooling fins for debris or any other obstruction. Inspect the drive belt system and the drive belt tensioner for proper operation in order to ensure that the coolant pump is rotating properly. Inspect for loose, damaged and/or missing air deflector(s). Check for a pinched or kinked cooling system hose. Repair the systems as necessary. Does the engine still overheat? | Go to Step 5 | System OK |
| 5 | Inspect the thermostat for proper operation. Refer to THERMOSTAT DIAGNOSIS . Is the thermostat operating properly? | Go to Step 7 | Go to Step 6 |
| 6 | Replace the thermostat. Refer to THERMOSTAT REPLACEMENT . Does the engine still overheat? | Go to Step 7 | System OK |
| 7 | NOTE: Excessive coolant freeze point protection MAY cause the coolant to boil at low temperatures. Inspect for the proper coolant concentration (mixture). Correct the coolant concentration as necessary. Remove the radiator cap. Start the engine and inspect for a constant flow of air bubbles in the engine coolant. Is there a constant flow of air bubbles in the engine coolant? | Go to Step 8 | Go to Step 9 |
| 8 | The probable cause of the engine overheat is combustion chamber gasses leaking into the cooling system. This condition is usually caused by the following: A worn or damaged cylinder head gasket A worn or damaged cylinder head A worn and/or damaged engine block Verify this condition by inspecting the spark plug electrodes and porcelain surrounding the spark plug electrode for signs of coolant. Replace and/or repair the engine internal component(s), as necessary, in order to repair the engine internal coolant leak. Does the engine still overheat? | Go to Step 1 | System OK |
| 9 | The engine overheat may be caused by a cooling system blockage. Flush the cooling system. Refer to COOLANT SYSTEM FLUSHING . Does the engine still overheat? | Go to Step 10 | System OK |
| 10 | NOTE: It is unlikely that the water pump is the cause of the overheat condition. If NONE of the cooling system passages are restricted, replace the coolant pump. Refer to WATER PUMP REPLACEMENT .Does the engine still overheat? | Go to Step 1 | System OK |
| NOTE |
|---|
| Excessive coolant freeze point protection MAY cause the coolant to boil at low temperatures. |
| NOTE |
|---|
| It is unlikely that the water pump is the cause of the overheat condition. |
ENGINE OVERHEATING DIAGNOSTIC PROCEDURE
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 TROUBLE CODE (DTC) LIST - VEHICLE DIAGNOSTIC INFORMATION . Is the action complete? | Go to Step 3 | |
| 3 | Inspect the coolant level. Is the coolant at the proper level? | Go to Step 6 | Go to Step 4 |
| 4 | Fill the cooling system to the proper level. Refer to DRAINING AND FILLING COOLING SYSTEM (LY7 GE 47716 FILL) and DRAINING AND FILLING COOLING SYSTEM (LY7 STATIC FILL) . Is the action complete? | Go to Step 5 | |
| 5 | If the engine is suspected to have a coolant leak into a cylinder, the coolant can hydraulically lock the engine. Does the engine crankshaft rotate? | Go to Step 6 | Go to Step 26 |
| 6 | Engine overheating can cause a loss of coolant. Is the engine overheating? | Go to Step 27 | Go to Step 7 |
| 7 | Extended operation with a low coolant level can cause engine internal component failure. Is the engine knocking? | Go to Step 29 | Go to Step 8 |
| 8 | 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 9 | Go to Step 10 |
| 9 | 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 28 | Go to Step 10 |
| 10 | With the engine idling, inspect the coolant recovery system. Does the coolant recovery system discharge coolant while the engine is idling? | Go to Step 15 | Go to Step 11 |
| 11 | Visually inspect the hoses, pipes and hose clamps at the following locations: Coolant surge tank Heater core Radiator Are any of the hoses, clamps or pipes leaking? | Go to Step 20 | Go to Step 12 |
| 12 | Visually inspect the following components: The coolant pressure cap The core plugs The cylinder head gaskets The engine block The intake manifold The radiator The thermostat housing The water pump Are any of the listed components leaking? | Go to Step 20 | Go to Step 13 |
| 13 | Pressure test the cooling system. Refer to COOLING SYSTEM LEAK TESTING . With the cooling system pressurized, visually inspect the components listed in steps 11 and 12. Are any leaks present? | Go to Step 20 | Go to Step 14 |
| 14 | Pressure test the coolant pressure cap. Refer to PRESSURE CAP TESTING . Does the coolant pressure cap hold pressure? | Go to Step 16 | Go to Step 21 |
| 15 | Pressure test the coolant pressure cap. Refer to PRESSURE CAP TESTING . Does the coolant pressure cap hold pressure? | Go to Step 30 | Go to Step 21 |
| 16 | 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 22 | Go to Step 17 |
| 17 | Inspect the underside of the engine oil fill cap for a gray/white milky substance. Is there a milky substance on under the oil fill cap? | Go to Step 18 | Go to Step 19 |
| 18 | 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 28 | Go to Step 19 |
| 19 | 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 23 | Go to Step 31 |
| 20 | Repair or replace the leaking component. Refer to the appropriate repair. Is the repair complete? | Go to Step 31 | |
| 21 | Replace the coolant pressure cap. Is the repair complete? | Go to Step 31 | |
| 22 | Replace the heater core. Refer to HEATER CORE REPLACEMENT . Is the repair complete? | Go to Step 31 | |
| 23 | Remove the transmission oil cooler lines from the radiator. Pressure test the cooling system. Refer to COOLING SYSTEM LEAK TESTING . Inspect the transmission oil cooler for coolant. Is coolant present? | Go to Step 24 | Go to Step 25 |
| 24 | Replace the radiator. Refer to RADIATOR REPLACEMENT . Service the automatic transmission. Refer to ENGINE COOLANT/WATER IN TRANSMISSION . Is the repair complete? | Go to Step 31 | |
| 25 | Install the cooler lines to the radiator. Is the action complete? | Go to Step 31 | |
| 26 | Repair the engine no crank condition. Refer to ENGINE WILL NOT CRANK - CRANKSHAFT WILL NOT ROTATE . Is the repair complete? | Go to Step 31 | |
| 27 | Repair the engine overheating condition. Is the repair complete? | Go to Step 31 | |
| 28 | Repair the engine internal coolant leak. Refer to COOLANT IN COMBUSTION CHAMBER . Is the repair complete? | Go to Step 31 | |
| 29 | Repair the engine knock. Refer to LOWER ENGINE NOISE, REGARDLESS OF ENGINE SPEED . Is the repair complete? | Go to Step 31 | |
| 30 | Repair the combustion pressure in the cooling system problem. Refer to CYLINDER LEAKAGE TEST . Is the repair complete? | Go to Step 31 | |
| 31 | 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 DIAGNOSTIC PROCEDURE
Engine Fails To Reach Normal Operating Temperature
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Ensure that the cooling system is full. Allow the engine to cool. Start the engine. Turn the air conditioning system off. Inspect the engine cooling fan(s). Is the electric cooling fan on? | Go to Step 2 | Go to Step 3 |
| 2 | Diagnose and repair the cooling fan system. Refer to COOLING FAN ALWAYS ON . Verify the customer complaint. Does the engine still fail to reach normal operating temperature? | Go to Step 3 | System OK |
| 3 | Install the Scan Tool to the DLC. Compare the Scan Tool coolant temperature reading to the I/P cluster coolant temperature. Is the I/P cluster coolant temperature close to the reading on the Scan Tool? | Go to Step 5 | Go to Step 4 |
| 4 | Diagnose and repair the coolant temperature gage system. Verify the customer complaint. Does the engine still fail to reach normal operating temperature? | Go to Step 5 | System OK |
| 5 | Inspect the thermostat for proper operation. Refer to THERMOSTAT DIAGNOSIS . Is the thermostat operating properly? | Go to Step 1 | Go to Step 6 |
| 6 | Replace the thermostat. Refer to THERMOSTAT REPLACEMENT . Verify the customer complaint. Does the engine still fail to reach normal operating temperature? | Go to Step 1 | System OK |
DIAGNOSTIC PROCEDURE - ENGINE FAILS TO REACH NORMAL OPERATING TEMPERATURE
Filling Procedure
| CAUTION | All entrapped air must be purged from the powertrain cooling system before the final coolant level can be determined. Proper coolant level is critical to avoid engine damage. |
Note. The vehicle must be level when filling the cooling system.
- Slowly add a mixture of 50/50 DEX-COOL antifreeze and clean water to the coolant surge tank.
- Start the engine and check for leaks.
- Run the engine and cycle the vehicle from idle to 3,000 RPM in 30 second intervals until the engine cooling fan comes ON, the engine cooling fan turns ON at approximately 102°C (216°F). Repeat this process twice before the engine is turned OFF.
- Return the engine to idle, and idle for 30 seconds, then turn the engine OFF.
- Allow the vehicle to cool, before adding additional coolant. NOTE: The level in the surge tank will return into the cold fill range once the vehicle cools.
- Add additional coolant to the surge tank until the level is approximately 13 mm (0.5 in) above the surge tank seam.
- Install the coolant surge tank cap.
Cleaning Procedure
| CAUTION | Do not immerse the water pump in solvent. The solvent may enter the water pump's permanently lubricated bearings and cause premature bearing failure. |
- Remove the old gasket material from the water pump sealing surfaces.
- Clean all excess dirt and debris from the water pump housing.
Scheme 118
Scheme 119
Scheme 120
- Rotate the water pump hub (1). The water pump hub and impeller should turn straight and smoothly. If the hub wobbles, is noisy, or feels rough when rotated, replace the water pump.
- Inspect the exterior of the water pump for the following: Damage to the water pump hub bolt threads (2) for the water pump pulley Damage to the water pump bolt holes (3)
- Examine the water pump shaft (1) and the weep hole reservoir (2) in the water pump body for signs of leakage. If coolant leakage is evident, replace the water pump.
- Inspect the interior of the water pump for the following: Damage to the water pump gasket sealing surface (1) Damage, corrosion or restrictions to the water pump impeller (2) Damage, corrosion or restrictions to the coolant passages (3)
- Repair or replace the water pump as necessary.
Reference: WATER PUMP INSTALLATION .
Tools and Equipment
- Special tools are listed and illustrated throughout this section, with a complete listing at the end of the article. These tools, or their equivalents, are designed to quickly and safely accomplish the operations for which they are intended. The use of these special tools also minimize possible damage to engine components. Some precision measuring tools are required for inspection of certain critical components. Torque wrenches and a torque angle meter are necessary for the proper tightening of various fasteners.
- To properly service the engine assembly, the following items should be readily available: Approved eye protection and safety gloves A clean, well-lit, work area A suitable component cleaning tank A compressed air supply Trays or storage containers to keep components and fasteners organized An adequate set of hand tools Approved engine repair stand An approved engine lifting device that adequately supports the weight of the components