Important Preliminary Checks
Before using this section, perform the Powertrain On-Board Diagnostic
(OBD) System Check and verify all of the following items:
| • | The PCM and MIL are operating correctly. |
| • | There are no DTC(s) 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 Cooling for diagnosis. |
| • | Scan tool data is within normal operating range. Refer to Typical
Scan Data Values. |
| • | Verify the customer complaint and locate the applicable symptoms.
Perform the procedure included in the symptom diagnostic table. |
The following Symptom tables are located in this section:
Visual/Physical Checks
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. |
| • | Ignition wires for cracking, hardness, proper routing and carbon
tracking. |
| • | Wiring for improper connections, pinches and cuts. |
