Diagnostic Starting Point

Begin the diagnosis of the [1][2]data link communications by performing the Diagnostic System Check for the system in which the customer concern is apparent. The Diagnostic System Check will direct you to the correct procedure within the Data Link Communications section when a communication malfunction is present.

Displaying DTCs
A DTC is read in only one of following two ways:
^ The IPC Reading DTC feature.
^ Using a scan tool

Information in diagnostic tables will refer to the scan tool for diagnostic support. For details on using the on-board diagnostic feature to access and/or clear DTCs. Refer to Vehicle On-Board Diagnostics.

Clearing DTCs
Disconnecting the battery and/or the BCM connectors will not clear a DTC. A DTC can only be cleared in one of the following three ways:
^ Using the IPC Clearing feature.
^ Using a scan tool.
^ The BCM will automatically clear a DTC if the malfunction has not occurred within 50 ignition cycles.

Information in diagnostic tables will refer to the scan tool for diagnostic support. For details on using the onboard diagnostic feature to access and/or clear DTCs. Refer to Vehicle On-Board Diagnostics.

Clear any history DTC after a system malfunction is corrected in order to prevent future misdiagnosis.