Important Preliminary Inspections Before Starting
Before using the Symptom diagnosis, perform the following:
| - | Ensure that the engine control module (ECM) and indicator lamp are operating correctly. |
| - | Ensure that there are no diagnostic trouble codes (DTCs) that are stored. |
| • | 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 system operation in order to familiarize yourself with the system functions. Refer to
Cooling Fan Description and Operation.
Visual/Physical Inspection
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:
| • | Ensure that the control module grounds are clean, tight, and correctly located. |
| • | Inspect cooling system hoses and pipes for splits, kinks, and proper connections. Inspect thoroughly for any type of a leak or a restriction. |
| • | Inspect for a dirty or restricted radiator and 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 the 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 determine an intermittent condition:
| • | Moisture and water intrusion in connectors, terminals, and components |
| • | 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 is located too tight, or chaffed circuits |
| • | High or low ambient temperature |
| • | High or low engine coolant temperatures |
| • | High underhood temperatures |
| • | Heat build up in component or circuit due to circuit resistance, poor terminal contact, or high electrical load |
| • | High or low system voltage |
| • | High vehicle load conditions |
| • | Electro-magnetic interference (EMI)/circuit interference from relays, solenoids or other electrical surge |
| • | 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.
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:
