Contents Wiring diagrams Section: Cooling System (Mechanical) All sections

Engine Cooling System: Other Chevrolet Tahoe III

Cooling System (Mechanical) 3 illustrations ~1979 words

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

  1. «Component Connector End Views»(ref-364487-S16896375592010063000000)
  2. «Powertrain Component Views»(ref-364590-S31266568172010063000000)
  3. «Electrical Center Identification Views»(ref-364507-S20856893292010063000000)

Description and Operation

Cooling Fan Description and Operation (Gas)

Electrical Information Reference

  1. «Circuit Testing»(ref-364488-S04114729552010063000000)
  2. «Connector Repairs»(ref-364488-S23771656832010063000000)
  3. «Testing for Intermittent Conditions and Poor Connections»(ref-364488-S16423338542010063000000)
  4. «Wiring Repairs»(ref-364488-S17530456672010063000000)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References

Circuit/System Verification

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

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Relay Replacement (Attached to Wire Harness)»(ref-364493-S18150273522010063000000) or «Relay Replacement (Within an Electrical Center)»(ref-364493-S12240576782010063000000)
  2. «Underhood Electrical Center or Junction Block Replacement»(ref-364493-S07637620422010063000000)
  3. «Engine Coolant Fan Replacement (Non-HP2)»(ref-364492-S28221606882010063000000)
  4. «Control Module References»(ref-364489-S22329914082010063000000) for ECM replacement, setup, and programming

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

  1. «Component Connector End Views»(ref-364487-S16896375592010063000000)
  2. «Powertrain Component Views»(ref-364590-S31266568172010063000000)
  3. «Electrical Center Identification Views»(ref-364507-S20856893292010063000000)

Description and Operation

Cooling Fan Description and Operation (Gas)

Electrical Information Reference

  1. «Circuit Testing»(ref-364488-S04114729552010063000000)
  2. «Connector Repairs»(ref-364488-S23771656832010063000000)
  3. «Testing for Intermittent Conditions and Poor Connections»(ref-364488-S16423338542010063000000)
  4. «Wiring Repairs»(ref-364488-S17530456672010063000000)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Relay Replacement (Attached to Wire Harness)»(ref-364493-S18150273522010063000000) or «Relay Replacement (Within an Electrical Center)»(ref-364493-S12240576782010063000000)
  2. «Underhood Electrical Center or Junction Block Replacement»(ref-364493-S07637620422010063000000)
  3. «Engine Coolant Fan Replacement (HP2)»(ref-364492-S07224185142010063000000)
  4. «Control Module References»(ref-364489-S22329914082010063000000) for ECM replacement, setup and programming

All V8

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

6.0L-Hybrid

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

Description and Operation

  1. «Cooling System Description and Operation»(ref-364492-S34044851002010063000000)
  2. «Instrument Cluster Description and Operation»(ref-364482-S22515779662010063000000)
  3. «Indicator/Warning Message Description and Operation»(ref-364482-S41895345332010063000000)
  4. «Audible Warnings Description and Operation»(ref-364482-S42423077952010063000000)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

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

  1. Observe the engine coolant level. The engine coolant level should be within operating range. Refer to «Cooling System Draining and Filling (Static Fill)»(ref-364492-S20837984752010063000000)
  2. Ensure that the vehicle has the correct engine coolant, with correct concentration, and is not old, contaminated or contains additives. Refer to «Cooling System Draining and Filling (Static Fill)»(ref-364492-S20837984752010063000000)
  3. Inspect the cooling system for the following: Leaks Kinked or pinched hoses, especially at the radiator Loose, missing, or damaged radiator air seals or deflectors The radiator and A/C condenser for any air flow obstructions or bent fins-Refer to «Symptoms - Engine Cooling»(ref-364492-S06578052992010063000000) .
  4. Command the cooling fans ON in each available speed with a scan tool. If the cooling fans are inoperative in any of the commanded states, refer to «Cooling Fan Inoperative (without HP2)»(ref-364492-S20987652682010063000000) or «Cooling Fan Inoperative (with HP2)»(ref-364492-S19487388372010063000000) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Identifying Intermittent Conditions

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

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

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

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation (Gas)

Electrical Information Reference

  1. «Circuit Testing»(ref-364488-S04114729552010063000000)
  2. «Connector Repairs»(ref-364488-S23771656832010063000000)
  3. «Testing for Intermittent Conditions and Poor Connections»(ref-364488-S16423338542010063000000)
  4. «Wiring Repairs»(ref-364488-S17530456672010063000000)
  1. Verify that the following DTCs are not set: P0480 or P0481. If a DTC is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(ref-364486-S07394808542010063000000) .
  2. Ignition ON, verify with a scan tool that the control module is not commanding fan activation.
  3. Ignition ON, observe that the fans are not activated.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Relay Replacement (Attached to Wire Harness)»(ref-364493-S18150273522010063000000) or «Relay Replacement (Within an Electrical Center)»(ref-364493-S12240576782010063000000)
  2. «Underhood Electrical Center or Junction Block Replacement»(ref-364493-S07637620422010063000000)

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation (Gas)

Electrical Information Reference

  1. «Circuit Testing»(ref-364488-S04114729552010063000000)
  2. «Connector Repairs»(ref-364488-S23771656832010063000000)
  3. «Testing for Intermittent Conditions and Poor Connections»(ref-364488-S16423338542010063000000)
  4. «Wiring Repairs»(ref-364488-S17530456672010063000000)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

  1. Verify that the following DTCs are not set: P0480, P0481, P0482. If a DTC is set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(ref-364486-S07394808542010063000000) .
  2. Verify with a scan tool that the ECM is not commanding fan relay activation.
  3. Ignition ON, observe that the fans are not activated.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Relay Replacement (Attached to Wire Harness)»(ref-364493-S18150273522010063000000) or «Relay Replacement (Within an Electrical Center)»(ref-364493-S12240576782010063000000)
  2. «Underhood Electrical Center or Junction Block Replacement»(ref-364493-S07637620422010063000000)

Schematic Reference

Engine Cooling Schematics

Description and Operation

Cooling Fan Description and Operation (Gas)

Connector End View Reference

Component Connector End Views

Electrical Information Reference

  1. «Circuit Testing»(ref-364488-S04114729552010063000000)
  2. «Connector Repairs»(ref-364488-S23771656832010063000000)
  3. «Testing for Intermittent Conditions and Poor Connections»(ref-364488-S16423338542010063000000)
  4. «Wiring Repairs»(ref-364488-S17530456672010063000000)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0480 or P0481 is not set. If a DTC is set, refer to «DTC P0480 or P0481 (without HP2)»(ref-364492-S40247422892010063000000) .
  2. Ignition ON, command high and low speed fans ON and OFF with a scan tool. Verify that both fans turn ON and OFF when changing between the commanded states.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Engine Coolant Fan Motor Replacement (Non-HP2)»(ref-364492-S07107917972010063000000)
  2. «Relay Replacement (Attached to Wire Harness)»(ref-364493-S18150273522010063000000) or «Relay Replacement (Within an Electrical Center)»(ref-364493-S12240576782010063000000)
  3. «Underhood Electrical Center or Junction Block Replacement»(ref-364493-S07637620422010063000000)

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling Fan Description and Operation (Gas)

Electrical Information Reference

  1. «Circuit Testing»(ref-364488-S04114729552010063000000)
  2. «Connector Repairs»(ref-364488-S23771656832010063000000)
  3. «Testing for Intermittent Conditions and Poor Connections»(ref-364488-S16423338542010063000000)
  4. «Wiring Repairs»(ref-364488-S17530456672010063000000)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0480 or P0481 is not set. If a DTC is set, refer to «DTC P0480, P0481, or P0482 (with HP2)»(ref-364492-S16561502892010063000000) .
  2. Ignition ON, command the cooling fans ON and OFF at high, medium, and low speed with a scan tool. Verify that both fans turn ON and OFF when changing between the commanded states.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Relay Replacement (Attached to Wire Harness)»(ref-364493-S18150273522010063000000) or «Relay Replacement (Within an Electrical Center)»(ref-364493-S12240576782010063000000)
  2. «Underhood Electrical Center or Junction Block Replacement»(ref-364493-S07637620422010063000000)
  3. «Engine Coolant Fan Motor Replacement (HP2)»(ref-364492-S02075584442010063000000)
  4. «Engine Coolant Fan Resistor Replacement (Right HP2)»(ref-364492-S20941705582010063000000) or «Engine Coolant Fan Resistor Replacement (Left HP2)»(ref-364492-S04190772202010063000000)

Engine Overheating

StepActionYesNo
1Inspect for a missing or damaged radiator side or upper baffle and/or radiator air deflector. Is the baffle and/or deflector missing or damaged?Go to Step 8Go to Step 2
2Inspect for a loss of coolant. Is there a loss of coolant?Go to Step 3Go to Step 4
3Fill the system to the specified level. Does the engine overheat?Go to Step 4System OK
4Inspect for low temperature protection. Is the coolant to the correct concentration?Go to Step 5Go to Step 8
5Inspect for a loss of cooling system pressure. Is there a loss of system pressure?Go to Step 8Go to Step 6
6Inspect for a faulty engine coolant temperature (ECT) sensor. Refer to DTC P0117 or P0118 (Without L96) . Is the sensor operating properly?Go to Step 7Go to Step 8
7Inspect for the following: Damaged coolant surge tank Leaking hose Bad/incorrect surge tank or radiator cap Were any of the above found?Go to Step 8Go to Step 3
8Repair or install new parts as necessary, then retest. Does the engine overheat?Go to Step 9System OK
9Inspect for incorrect drive belt tension. Is the belt tension correct?Go to Step 10Go to Step 8
10Remove the water pump. Refer to Water Pump Replacement . Inspect for a damaged water pump shaft/hub. Is the water pump driveshaft damaged or is the seal leaking?Go to Step 8Go to Step 11
11Inspect for obstructed radiator air flow or bent radiator fins. Is the radiator air flow obstructed?Go to Step 8Go to Step 12
12Inspect for blocked cooling system passages. Are the cooling system passages blocked?Go to Step 8Go to Step 13
13Inspect the thermostat. Refer to Thermostat Diagnosis . Is the thermostat stuck in the closed position?Go to Step 15Go to Step 16
14Replace the thermostat. Refer to Engine Coolant Thermostat Housing Replacement (LFA,LH6, LMG,LY2, LY5,LY6) . Does the engine overheat?Go to Step 16System OK
15Inspect the radiator cooling capacity. Is the proper sized radiator being used on the vehicle?Go to Step 3Go to Step 17
16Consult the current parts catalog and replace the radiator. Refer to Radiator Replacement (HP2) . Is the repair complete?System OK

Loss of Coolant

StepActionYesNo
DEFINITION: The cooling system is loosing coolant either internally or externally.
1Were you sent here from Symptoms, or another diagnostic table?Go to Step 2Go to Symptoms - Engine Cooling
2Repair any present DTCs. Refer to Diagnostic System Check - Vehicle . Is the action complete?Go to Step 3
3Inspect the coolant level. Is the coolant at the proper level?Go to Step 5Go to Step 4
4Fill the cooling system to the proper level. Refer to Cooling System Draining and Filling (Static Fill) . Is the action complete?Go to Step 5
5Engine overheating can cause a loss of coolant. Is the engine overheating?Go to Step 19Go to Step 6
6Idle 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 7Go to Step 8
7Coolant 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 20Go to Step 8
8Visually inspect the hoses, pipes and hose clamps. Are any of the hoses, clamps or pipes leaking?Go to Step 21Go to Step 9
9Visually 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 21Go to Step 10
10Pressure 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 21Go to Step 11
11Pressure test the coolant pressure cap. Refer to Pressure Cap Testing . Does the coolant pressure cap hold pressure?Go to Step 12Go to Step 16
12Inspect 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 21Go to Step 13
13Inspect 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 14Go to Step 15
14Inspect 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 17Go to Step 15
15Inspect 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 18Go to Step 22
16Replace the coolant pressure cap. Is the repair complete?Go to Step 22
17Replace the radiator. Refer to Radiator Replacement (HP2) . Replace the oil and filter. Refer to Engine Oil and Oil Filter Replacement Is the repair complete?Go to Step 22
18Replace the radiator. Refer to Radiator Replacement (HP2) . Service the automatic transmission. Refer to Engine Coolant/Water in Transmission . Is the repair complete?Go to Step 22
19Repair the engine overheating condition. Refer to Engine Overheating . Is the repair complete?Go to Step 22
20Repair the engine internal coolant leak. Refer to Coolant in Combustion Chamber or, Coolant in Engine Oil . Is the repair complete?Go to Step 22
21Repair or replace the leaking component. Refer to the appropriate repair. Is the repair complete?Go to Step 22
22Operate the system in order to verify the repair. Did you find and correct the condition?System OKGo to Step 2

Tools Required

J 24731: Tempil Stick

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

Electrical Information Reference

  1. «Circuit Testing»(ref-364488-S04114729552010063000000)
  2. «Connector Repairs»(ref-364488-S23771656832010063000000)
  3. «Wiring Repairs»(ref-364488-S17530456672010063000000)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Coolant Heater Replacement (With LC9, L76,or L92)»(ref-364492-S30147478742010063000000) or «Coolant Heater Replacement (With LY2, LMG, LY5, LY6 or LFA)»(ref-364492-S27017248072010063000000)
  2. «Coolant Heater Cord Replacement (With LY2, LY5 or LMG)»(ref-364492-S22342735942010063000000) or «Coolant Heater Cord Replacement (With LC9, LY6, L92 or LFA)»(ref-364492-S35836561462010063000000) or «Coolant Heater Cord Replacement (With LY6)»(ref-364492-S23571217762010063000000)

Engine Fails To Reach Normal Operating Temperature

StepActionYesNo
1Did you review the Symptoms - Engine Cooling diagnostic information and perform the necessary inspections?Go to Step 2Go to Symptoms - Engine Cooling
2Verify that the engine does not reach normal operating temperature. Does the engine reach normal operating temperature?System OKGo to Step 3
3Inspect the coolant level. Is the coolant level below the add mark?Go to Step 4Go to Step 5
4Add coolant as necessary. Perform a cooling system pressure test. Does the cooling system hold pressure?System OKGo to Step 5
5Inspect for a stuck open, missing, or incorrect thermostat. Refer to Thermostat Diagnosis . Is the thermostat operating properly?System OKGo to Step 6
6Install the correct replacement thermostat. Refer to Engine Coolant Thermostat Housing Replacement (LFA,LH6, LMG,LY2, LY5,LY6) . Is the repair complete?Go to Step 7
7Run the engine in order to verify the repair. Does the engine fail to reach normal operating temperature?System OK

Filling Procedure

  1. Install the lower radiator hose and/or drain cock to the radiator.
  2. Using the J 38185 , reposition the lower radiator hose clamp. See «Special Tools»(ref-364492-S13195046632010063000000) .
  3. If the left and right engine block coolant drain plugs were removed, perform the following: Apply pipe sealer to the drain plugs. Install the drain plugs. Tighten: Tighten the drain plugs to 60 N.m (44 lb ft).
  4. Install the engine block coolant heater, if equipped. Refer to «Coolant Heater Replacement (With LC9, L76,or L92)»(ref-364492-S30147478742010063000000) or «Coolant Heater Replacement (With LY2, LMG, LY5, LY6 or LFA)»(ref-364492-S27017248072010063000000) .
  5. Lower the vehicle.
  6. Slowly fill the cooling system with a 50/50 coolant mixture. Refer to «Approximate Fluid Capacities»(ref-364508-S03245074232010063000000) .
  7. Install the coolant pressure cap.
  8. Start the engine.
  9. Run the engine at 2,000-2,500 RPM until the engine reaches normal operating temperature. Engine should reach an operating temperature of 90°C (194°F) and the upper radiator hose should be HOT.
  10. Allow the engine to idle for 3 minutes.
  11. Shut the engine OFF.
  12. Allow the engine to cool.
  13. Top off the coolant as necessary.
  14. Inspect the concentration of the engine coolant using the J 26568 . See «Special Tools»(ref-364492-S13195046632010063000000) .
  15. Rinse away any excess coolant from the engine and the engine compartment.

Radiator Cleaning

WARNINGNEVER spray water on a hot heat exchanger. The resulting steam could cause personal injury.
CAUTIONThe heat exchanger fins are necessary for good heat transfer. Do not brush the fins. This may cause damage to the fins, reducing heat transfer.
  1. Some conditions may require the use of warm water and a mild detergent.
  2. Clean the A/C condenser fins.
  3. Clean between the A/C condenser and radiator.
  4. Clean the radiator cooling fins.
  5. Straighten any damaged cooling fins.

Scheme 27

Scheme 27: Radiator Surge Tank Replacement (Non-HP2)
CalloutComponent Name
Preliminary Procedure Drain the cooling system. Refer to Cooling System Draining and Filling (Static Fill) . Remove the air cleaner assembly. Refer to Air Cleaner Assembly Replacement .
1Surge Tank Bolt CAUTION: Refer to Fastener Caution . Tighten: 10 N.m (89 lb in)
2Surge Tank Nut Tighten: 10 N.m (89 lb in)
3Surge Tank Tip: Remove the surge tank hoses from the surge tank.
CAUTION
Refer to Fastener Caution .

Scheme 28

Scheme 28: Radiator Surge Tank Replacement (HP2)
CalloutComponent Name
Preliminary Procedures Drain the cooling system. Refer to Cooling System Draining and Filling (Static Fill) . Remove air cleaner assembly. Refer to Air Cleaner Assembly Replacement . Remove the radiator surge tank inlet hose/pipe. Refer to Radiator Surge Tank Inlet Hose/Pipe Replacement (HP2) . Remove the radiator surge tank outlet hose. Refer to Generator Control Module Coolant Inlet Hose Replacement . Reposition the radiator inlet hose to get access to the radiator surge tank bolts. Unclip the overflow hoses from the fan shroud.
1Radiator Surge Tank Bolt (Qty: 2) CAUTION: Refer to Fastener Caution . Tighten: 10 N.m (89 lb in)
2Radiator Surge Tank
CAUTION
Refer to Fastener Caution .

Scheme 29

Scheme 29: Radiator Surge Tank Inlet Hose/Pipe Replacement (HP2)
CalloutComponent Name
Preliminary Procedures: Partially drain the cooling system. Refer to Cooling System Draining and Filling (Static Fill) .
1Radiator Surge Tank Inlet Hose/Pipe Tip: Using J 38185 reposition the radiator surge tank inlet hose/pipe clamps. See Special Tools . Special Tools: J 38185 Surge Tank Inlet Hose/Pipe. See Special Tools .

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

Special Tools

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

ENGINE COOLANT HOT

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

ENGINE OVERHEATED

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

REDUCED ENGINE POWER

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

Coolant Heater

The optional engine coolant heater (RPO K05) operates using 110-volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather 29°C (20°F). The coolant heater helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. A weather shield on the cord is provided to protect the plug when not in use.