Envoy 2WD V6-4.3L VIN W (1998)
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Verified that the on-board diagnostics function correctly without displaying any DTCs
The typical scan tool data values are an average of displayed values that are recorded from normally operating vehicles. The typical scan tool data values
are intended to represent what a normally functioning system would display. The values you get may vary due to a low battery charge or other reasons.
The values should be very close.
Use only the parameters that the tables list for diagnosis. If a scan tool reads another parameter, do not use the values in diagnosis. For more details on
the scan tool typical data values and on the use of the scan tool for the diagnosis of BCM inputs, refer to the applicable diagnosis table. If all of the
values are within the range that the table illustrates, refer to Diagnostic Aids in the applicable diagnostic trouble code table and the Symptom Subsection
References Table.
Scan Tool Diagnosis
Use the scan tool in order to monitor the communications between the BCM and the PCM/VCM. The scan tool also displays Passlock data. The Passlock
data list display is located under the PASSLOCK selection. This list shows the status of the hardwired connections from the Passlock sensor to the BCM.
These scan tool values may be very useful in diagnosing the Passlock system.
The Passlock system is designed in order to deter theft, even if various parts are changed. The following components may not be changed without the
possibility of going into no-start condition:
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The Passlock sensor
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The Powertrain Control Module (PCM)
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The Body Control Module (BCM)
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The Vehicle Control Module (VCM)
If any of these parts are replaced, refer to the Learn Procedure in BCM Programming/RPO Configuration. The BCM and the PCM/VCM require the full
10 minutes in order to complete a lockout cycle. The ignition key MUST remain in the RUN position until the telltale turns to the OFF position. If the
ignition key is turned from the RUN position before the telltale turns to the OFF position, you will have to repeat the lockout cycle. The Passlock system
requires 3 consecutive lockout cycles in order to complete the 30 minute learn procedure for a changed component. Refer to Theft Deterrent
Diagnostic System Check for more information on the Passlock system.
Scan Tool Information Modes
On the scan tool, four modes are available in the body control module selection.
Select the following items:
1. Body control module
2. Data display
3. Data list
The following list appears on the scan tool:
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Data
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Input 1
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Input 2
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Outputs
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Security data
The scan tool allows for the for the display of Class 2 values, or the state of components commanded by the various systems (i.e. ATC, BCM, HVAC,
PC, PCM and VCM). The tests available are dependent upon the system selected, but may include the following modes:
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Data (analog inputs): This test displays analog values as seen by the system.
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Inputs (digital inputs): This test displays digital values as seen by the system and provides an indication of whether the input has cycled.
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Outputs (digital outputs): This test allows for digital outputs controlled by the BCM system in order to be turned OFF/ON.
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Special functions (analog outputs): This test allows for analog outputs of the BCM system to be set at a desired value.
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Clear diagnostic trouble codes: This test will erase all DTC's stored for the system currently selected (Note: If the malfunction is still present, the
DTC may immediately reset).
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Security data (content theft): This test contains information system applicable to the content theft system.
