G 1500 1/2 Ton Van L6-250 4.1L VIN D 2-bbl (1984)
Data Link Connector: Description and Operation
Figure 1 Terminal Arrangement In Connector
This connector is used in the assembly plant to connect a computer for checking of the system to see that it is functioning properly before shipping the
vehicle. To obtain trouble codes with the ignition switch on and the engine either stopped or running the "test" terminal in this connector should be
grounded. The "test" terminal should be ungrounded when starting the engine or the "Check Engine" lamp will not function properly. Refer to Figure 1.