Preliminary Inspections
Before using this section, perform the Diagnostic System Check-Engine
Controls and verify all of the following items:
| • | The engine control module (ECM) and malfunction indicator lamp
(MIL) are operating correctly. |
| • | There are no DTCs stored. |
| • | Scan tool data is within normal operating range. Refer to Typical
Scan Data Values. |
| • | Verify the customer complaint and locate the correct symptom in
the table of contents. Perform the procedure included in the symptom chart. |
Visual/Physical Inspections
Several of the symptom procedures call for a careful visual inspection.
This can lead to correcting a problem without further Inspections and can
save valuable time. This Inspection should include the following items:
| • | The ECM grounds for cleanliness, tightness, and proper location. |
| • | The vacuum hoses for splits, kinks, and proper connections, as
shown on the Vehicle Emission Control Information label. Inspect the hoses
thoroughly for any type of leak or restriction. |
| • | The air intake ducts for collapsed or damaged areas. |
| • | The fuel injection system component for cracking, hardness, and
carbon tracking. |
| • | The wiring for proper connections, pinches, and cuts. |
Intermittents
An intermittent problem may or may not turn ON the MIL or store a DTC.
Do not use the DTC charts for intermittent problems. The fault must be present
to locate the problem.
Most intermittent conditions are caused by faulty electrical connections
or wiring. Perform a careful visual inspection for the following conditions:
| • | Poor mating of the connector halves or a terminal not fully seated
in the connector (backed out). |
| • | Improperly formed or damaged terminal. |
| • | Inspect all connector terminals in the faulty circuit for proper
contact tension. |
| • | Remove the terminal from the connector body. Inspect for poor
terminal-to-wire connection. |
Road test the vehicle with a DMM connected to a suspected circuit. An
abnormal voltage when the malfunction occurs is a good indication that there
is a fault in the circuit being monitors.
Use a scan tool to help detect intermittent conditions.
Symptom List
Refer to a symptom diagnostic procedure from the following list in order
to diagnose the symptom.
