Engine Controls - Revised Diagnostic System Check
Bulletin No.: 04-06-04-020Date: April 07, 2004
SERVICE MANUAL UPDATE
Subject:
Revised Diagnostic System Check-Engine Controls
Models:
2001-2002 Chevrolet Express Van
2001-2002 GMC Savana Van
with 6.5L Engine (VIN F - RPO L65)
This bulletin is being issued to revise the Diagnostic System Check-Engine Controls in the Engine Controls sub-section of the Service Manual. Please replace the current information in the Service Manual with the following information.
The following information has been updated within SI. If you are using a paper version of this Service Manual, please make a reference to this bulletin on the affected page.
Test Description
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The numbers below refer to the step numbers on the diagnostic tables shown.
2. Lack of communication may be because of a partial or a total malfunction of the class 2 serial data circuit. The specified procedure determines the particular condition.
5. This step stores the powertrain control module (PCM) diagnostic trouble code (DTC) information into the scan tool's memory. After you complete the diagnostic procedure, review the captured information in order to catch the next DTC if the control module stores multiple DTCs. Review the Freeze Frame data and the Failure Records data. Use this information in order to determine how frequently and how recently the DTC set. This information may help diagnose an intermittent condition. Information about the operating conditions at the time that the DTC set may also help diagnose an intermittent condition. Capturing the stored information saves the data that the PCM loses during the following conditions:
^ When a diagnostic procedures instructs you to clear the DTCs.
^ When a diagnostic procedure instructs you to disconnect the PCM connectors.
^ When a diagnostic procedure instructs you to replace the PCM.
6. The presence of DTCs which begin with "U" indicate that some other module is not communicating. Following the specified procedure will gather all the available information before you perform the tests.
9. If there are other modules with DTCs set, refer to the DTC list. The DTC list directs you to the appropriate diagnostic procedure. If the control module stores multiple powertrain DTCs, diagnose the DTCs in the following order:
^ Component level DTCs, such as sensor DTCs, solenoid DTCs, and relay DTCs. Diagnose the multiple DTCs within this category in numerical order. Begin with the lowest numbered DTC, unless the diagnostic table directs you otherwise.
^ System level DTCs, for example, misfire DTCs, fuel trim DTCs, and catalyst DTCs.
11. This step is for areas that have inspection and maintenance testing procedures for emissions testing. Use this step if the testing facility found one or more I/M system statuses that did not set.
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