With 4L60-E Transmission

Data Link Connector(DLC):

ACCESSING
The means of communicating with the control module is the Data Link Connector (DLC) located under the instrument panel and is sometimes covered by a plastic cover labeled DIAGNOSTIC CONNECTOR." The DLC is used in the assembly plant to receive engine information to determine proper operation before it leaves the plant. The Diagnostic Trouble Code (DTC)(s) stored in the control module memory can be displayed either through the Tech 1 scan tool or a hand-held diagnostic scanner plugged into the DLC connector.

SCAN TOOL USE WITH INTERMITTENTS
A corresponding DTC will be stored in the memory of the PCM as a history DTC until DTCs have been cleared. When unexpected DTCs appear during the code reading process, one can assume that these DTCs were set by an intermittent malfunction and could he helpful in diagnosing the system.

An intermittent DTC may or may not re-set. If it is an intermittent failure. a Diagnostic Trouble Code (DTC) chart is not used. Consult the "Diagnostic Aids" on the diagnostic chart corresponding to the intermittent DTC. Refer to Intermittents. A physical inspection of the applicable sub-system most often will not resolve the problem.