Important Preliminary Inspections Before Starting
Before using the Symptom tables, perform the following:
| - | Ensure that the engine control module (ECM) and malfunction indicator lamp (MIL) 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. |
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.
Visual/Physical Check
Notice: Use the connector test adapter kit J 35616-A for any test that
requires probing the following items:
| • | The PCM harness connectors |
| • | The electrical center fuse/relay cavities |
| • | The component terminals |
| • | The component harness connector |
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:
| • | Inspect vacuum hoses for splits, kinks, and proper connections, as shown on the Vehicle Emission Control Information label. Inspect thoroughly for any type of a leak or a restriction. Refer to
Evaporative Emissions Hose Routing Diagram
. |
| • | Inspect for a dirty or restricted air filter. |
| • | Inspect for water intrusion in the mass air flow (MAF)/intake air temperature (IAT) sensor connector, heated oxygen sensor (HO2S) connectors, control module connectors or any other harness connectors. |
| • | Inspect the air intake ducts, particularly between the MAF sensor and the throttle body for the following conditions: |
| • | Inspect for air leaks at the throttle body mounting area, the MAF sensor and intake manifold sealing surfaces. |
| • | Inspect the wiring harness for the following conditions: |
| • | Inspect for loose, damaged, unseated, or missing sensors/components. |
| • | Inspect terminals for corrosion and correct contact. |
The following symptom tables are located in this section:
