Important Preliminary Checks
Before using this section, perform
Powertrain On Board Diagnostic (OBD) System Check
and verify all of the following
items:
| • | The PCM and MIL are operating correctly. |
| • | There are no DTCs stored. |
| • | Ensure that the engine coolant temperature is not above 128°C
(262°F). This condition will cause the PCM to operate in coolant hot mode.
While in coolant hot mode, the PCM will turn fuel OFF to three cylinders
to keep engine temperatures from reaching damaging levels. Coolant
hot mode will be perceived as a lack of power, miss, or rough idle.
If the vehicle is operating in coolant hot mode, refer to
Engine Overheating
in Engine Cooling for diagnosis. |
| • | Verify the customer complaint and locate the applicable symptoms.
Perform the procedure included in the symptom diagnostic table. |
Visual/Physical Check
Several of the symptom procedures call for a visual/physical inspection.
A careful visual/physical inspection can aid in correcting a problem without
further checks and can save valuable time. A visual/physical inspection
should include the following items:
| • | PCM grounds for being loose, corroded, or in an improper location. |
| • | Vacuum hoses for splits, kinks, and improper connections. The
proper connections are shown on the Vehicle Emission Control Information label.
Check the vacuum hoses for any type of leak or restriction. |
| • | Air intake ducts for collapsed or damaged areas. |
| • | Air leaks at throttle body mounting area, mass air flow (MAF)
sensor and intake manifold sealing surfaces. |
| | Important: If carbon tracking is detected on any component, replace that component
and its mate.
|
| • | Ignition wires for cracking, hardness, proper routing and carbon tracking. |
| • | Wiring for improper connections, pinches and cuts. |
The following Symptom tables are located in this section:
