No Communication On Class II Data Link

Diagnostic Chart:

Schematic:

If communications cannot be established with either the body control module (BCM) or the sensing and diagnostic module (SDM) the fault is related to the Class II link. Types of faults that will affect communications could be a short to ground, short to voltage, and open circuit between the data link connector (DLC) and the BCM. Internal controller faults could also cause communication errors on the data link. Because the Class II link is wired in a ring configuration, an open circuit, will not affect communications with the ECM.

This chart is used to diagnose faults associated with the Class II data link. When following this chart it will be necessary to refer to the facing page schematic because the Class II link configuration depends on the whether the vehicle is equipped with a 4 cylinder (L61) engine or the V-6 (L81) engine.