Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Lack of communication may be due to a partial malfunction of the GM LAN serial data circuit or due to a total malfunction of the GM LAN serial data circuit. The specified procedure will determine the particular condition.
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The symptom list in Symptoms will determine the correct diagnostic procedure to use.
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The presence of DTCs which begin with U indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.
Step | Action | Yes | No | ||||
|---|---|---|---|---|---|---|---|
1 |
Does the scan tool power up? | Go to Step 2 | Go to Scan Tool Does Not Power Up in Data Link Communications | ||||
Attempt to establish communication with the following:
Does the scan tool communicate with all devices present? | Go to Step 3 | Go to Scan Tool Does Not Communicate with Low Speed GMLAN Device in Data Link Communications | |||||
Select the following display DTC functions on the scan tool:
Does the scan tool display any DTCs? | Go to Step 4 | Go to Symptoms - Entertainment | |||||
Does the scan tool display any DTCs which begin with a U? | Go to Scan Tool Does Not Communicate with Low Speed GMLAN Device in Data Link Communications | Go to Step 5 | |||||
5 | Does the scan tool display DTC B1000? | Go to Diagnostic Trouble Code (DTC) List in Body Control System | Go to Step 6 | ||||
6 | Does the scan tool display DTC B1325? | Go to Diagnostic Trouble Code (DTC) List in Engine Electrical |
