Symptoms - Engine Cooling

Symptoms - Engine Cooling

Important Preliminary Inspections Before Starting

Before using the Symptom diagnosis, perform the following:

* Perform Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle and verify all of the following items:

- Engine control module (ECM) and indicator lamp are operating correctly.

- There are no diagnostic trouble codes (DTCs) stored.

- Scan tool data is within a normal operating range.

* Verify the customer concern.

* 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.

* Locate the correct symptom. Perform the tests and inspections associated with the symptom.

Review the entire cooling system operation in order to familiarize yourself with the system functions. Refer to Cooling Fan Description and Operation Cooling Fan and Cooling System Description and Operation Cooling System.

Visual/Physical Inspection

Caution:
Use the connector test adapter kit EL-35616-F for any test that requires probing the following items:

* The control module harness connectors

* The electrical center fuse/relay cavities

* The component terminals

* The component harness connector

Using this kit will prevent damage caused by the improper probing of connector terminals.

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:

* Ensure that the control module grounds are clean, tight, and correctly located.

* Inspect cooling system hoses and pipes for splits, kinks, and improper connections. Inspect thoroughly for any type of leak or restriction.

* Inspect for a dirty or restricted radiator or HVAC condenser.

* Inspect for aftermarket devices which could affect the operation of the cooling system.

* Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

* Inspect the surge tank reservoir for proper coolant level.

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 isolate an intermittent condition:

* Water intrusion in connectors, terminals, or components

* Poor connector mating

* Terminal contact

* High circuit or component resistance-High resistance can include any resistance, regardless of the amount, which can interrupt the operation of the component.

* Harness' that are routed too tight, or chaffed circuits

* High or low ambient temperatures

* High or low engine coolant temperatures

* High underhood temperatures

* Heat build up in components or circuits due to circuit resistance, poor terminal contact, or high electrical load

* High or low system voltage

* High vehicle load conditions

* Rough road surface

* Electro-magnetic interference (EMI)/circuit interference from relays, solenoids or other electrical surge

* Incorrect installation of non-factory, aftermarket, or after factory add on accessories

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

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

* Cooling Fan Always On Cooling Fan Always On

* Cooling Fan Inoperative Cooling Fan Inoperative

* Engine Overheating Engine Overheating

* Loss of Coolant Loss of Coolant

* Thermostat Diagnosis Thermostat Diagnosis

* Engine Fails To Reach Normal Operating Temperature Engine Fails To Reach Normal Operating Temperature