Symptoms - Engine Cooling
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Symptoms - Engine Cooling
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Important Preliminary Inspections Before Starting
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Before using the Symptom diagnosis, perform the following:
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Ensure that the engine control module (ECM) and indicator lamp are operating correctly.
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Ensure that there are no diagnostic trouble codes (DTCs) that are stored.
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Verify the customer concern.
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Perform the Visual/Physical Inspection in this section. The visual/physical inspection is extremely important, and can lead to correcting a condition without additional testing. It may also help reveal the cause of an intermittent condition.
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Locate the correct symptom. Perform the tests and inspections associated with the symptom.
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Review the system operation in order to familiarize yourself with the system functions. Refer to
Cooling Fan Description and Operation (Diesel)
Cooling Fan Description and Operation (LDK/A20NHT, LBW/A28NER, LAU/A28NET )
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Visual/Physical Inspection
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Several of the symptom procedures call for a careful visual and physical inspection. This can lead to correcting a condition without further tests and can save time. This inspection should include the following areas:
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Ensure that the control module grounds are clean, tight, and correctly located.
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Inspect cooling system hoses and pipes for splits, kinks, and proper connections. Inspect thoroughly for any type of a leak or a restriction.
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Inspect for a dirty or restricted radiator and HVAC condenser.
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Inspect for aftermarket devices which could affect the operation of the Cooling System.
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Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
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Inspect the surge tank reservoir for the proper coolant level.
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Identifying Intermittent Conditions
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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:
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Moisture and water intrusion in connectors, terminals, and components
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High resistance in circuits or components. High resistance can be a resistance, irrespective of size, that disrupts the function of components.
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Harness that is located too tight, or chaffed circuits
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High or low ambient temperature
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High or low engine coolant temperatures
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High underhood temperatures
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Heat build up in component or circuit due to circuit resistance, poor terminal contact, or high electrical load
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High or low system voltage
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High vehicle load conditions
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Electro-magnetic interference (EMI)/circuit interference from relays, solenoids or other electrical surge
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Incorrect installation of non-factory, aftermarket, and after factory add on accessories
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If an intermittent is determined, refer to
Testing for Intermittent Conditions and Poor Connections
for specific strategies in diagnosing intermittent conditions.
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:
