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Home >> Jeep >> 2021 >> Grand Cherokee L Laredo, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 2 (5.7L - Cooling System) >> Diagnosis And Testing >> Preliminary Checks >> Recent Service Or Accident Repair:

Recent Service Or Accident Repair:

WARNING: This page is about a different variant/trim than selected.

Determine if any recent service has been performed on vehicle that may affect the cooling system. This may be:

NOTE:

If investigation reveals none of the previous items as a cause for an engine overheating complaint, refer to the COOLING SYSTEM DIAGNOSIS CHART below.

These charts are to be used as a quick-reference only.

COOLING SYSTEM DIAGNOSIS CHART

CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE READS LOW
NOTE:

Information on dash cluster is displayed based on broadcast data from PCM. DTC will be set for engine sensor circuit issues.

 1. Vehicle is equipped with a heavy duty cooling system 1. None. System operating normally.
2. Thermostat stuck open 2. Inspect and test thermostat.
3. Coolant level low 3. Fill cooling system. Refer to COOLING SYSTEM FILLING  .
4. Temperature gauge not functioning correctly 4. Check cluster. Refer to INSTRUMENT PANEL CLUSTER .
5. Engine sensor stuck in range 5. Monitor sensor with scan tool to verify sensor reading changes with increasing temperature.
6. Engine sensor failed out of range 6. A DTC will be set.
TEMPERATURE GAUGE READS HIGH. COOLANT MAY OR MAY NOT BE LEAKING FROM SYSTEM
NOTE:

Temperature information displayed on dash cluster and Electronic Vehicle Information Center (EVIC) are based on broadcast data from PCM. If engine temperatures exceed thresholds, power is reduced and a message of 'Oil Temp High - Speed May be Reduced' is displayed on the EVIC.

 1. Vehicle overloaded, high ambient (outside) temperatures with A/C turned on, stop and go driving or prolonged operation at idle speeds 1. Temporary condition, repair not required. Notify customer of vehicle operation instructions located in Owners Manual.
2. Electronically controlled Pulse Width Modulation (PWM) fan not functioning correctly 2. Troubleshoot and if necessary repair the electronically controlled PWM fan.
3. Temperature gauge not functioning correctly 3. Check cluster. Refer to INSTRUMENT PANEL CLUSTER .
4. Air trapped in cooling system 4. Drain and refill cooling system. Refer to STANDARD PROCEDURE  .
5. Ineffective radiator cap 5. Replace radiator cap.
6. Plugged A/C or radiator cooling fins 6. Clean all debris away from A/C and radiator cooling fins.
7. Coolant mixture incorrect 7. Drain cooling system and refill with correct mixture. Refer to STANDARD PROCEDURE  .
8. Thermostat stuck shut 8. Inspect and test thermostat.
9. Bug screen or winter front being used 9. Remove bug screen or winter front.
10. Cylinder head gasket leaking 10. Check for leaking head gaskets. Refer to COOLING SYSTEM LEAKS  .
11. Heater core leaking 11. Replace heater core. Refer to CORE, HEATER, REMOVAL AND INSTALLATION .
12. Cooling system hoses leaking 12. Tighten the clamps or replace the hoses.
13. Brakes dragging 13. Check brakes. Refer to DIAGNOSIS AND TESTING .
14. Accessory drive belt 14. Inspect and replace as necessary.
15. Water Pump 15. Inspect and replace as necessary.
16. Engine sensor stuck in range 16. Monitor sensor with scan tool to verify sensor reading changes increase in temperature.
17. Temperature sensor failed - Too High 17. Clear the existing overheat fault. Drive the vehicle until thermostat opens. Verify that fault code does not return and coolant does not reach threshold of 230 degrees F.
TEMPERATURE GAUGE READING INCONSISTENT (ERRATIC, CYCLES OR FLUCTUATES)
NOTE:

Information on dash cluster is displayed based on broadcast data from PCM. DTC will be set for engine sensor circuit issues.

 1. Heavy duty cooling system, extreme cold ambient (outside) temperature or heater blower motor in high position 1. None. System operating normally.
2. Temperature gauge or sensor inoperative 2. Check cluster or engine coolant temp sensor. Refer to INSTRUMENT PANEL CLUSTER .
3. Temporary heavy usage or load 3. None. Normal condition.
4. Air trapped in cooling system 4. Fill cooling system. Refer to COOLING SYSTEM FILLING  .
5. Water pump 5. Replace water pump.
6. Air leak on suction side of water pump 6. Check for leak. Refer to COOLING SYSTEM LEAKS  .
RADIATOR CAP LEAKING STEAM AND OR COOLANT INTO RESERVOIR BOTTLE. (TEMPERATURE GAUGE MAY READ HIGH) 1. Radiator cap ineffective 1. Replace radiator cap.
2. Radiator neck surface damaged 2. Replace radiator.
HOSE OR HOSES COLLAPSE WHEN ENGINE IS COOLING 1. Vacuum created in cooling system on engine cool-down is not being relieved through coolant reservoir/overflow system 1. Replace radiator cap, check vent hose between radiator and reservoir bottle for blockage also check reservoir bottle vent for blockage.
NOISY FAN 1. Fan blade(s) loose, damaged 1. Replace the fan assembly.
2. Fan blades striking surrounding objects 2. Locate contact point and repair as necessary.
3. Obstructed air flow through radiator 3. Remove the obstruction.
INADEQUATE AIR CONDITIONER PERFORMANCE (COOLING SYSTEM SUSPECTED) 1. Radiator and/or A/C condenser air flow obstructed 1. Remove obstruction and/or clean.
2. Electronically controlled Pulse Width Modulation (PWM) fan not working 2. Check electronic PWM fan.
3. Air seals around radiator damaged or missing 3. Inspect air seals, repair or replace as necessary.
INADEQUATE HEATER PERFORMANCE. GAUGE MAY OR MAY NOT READ LOW 1. Heavy duty cooling system, and cooler ambient temperatures 1. None. Normal condition.
2. Obstruction in heater hoses 2. Remove hoses, remove obstruction.
3. Water pump damaged 3. Replace water pump.
HEAT ODOR 1. Damaged or missing exhaust system heat shields 1. Repair or replace damaged or missing exhaust system heat shields.
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