Normal Operation

The Body Control Module B (BCM-B) monitors the ignition switch position messages from the SJB  over the Medium Speed Controller Area Network (MS-CAN), and if it does not receive an ignition switch position message from the SJB  in more than 5 seconds, the BCM-B  will set this DTC in continuous memory. The BCM-B  monitors the MS-CAN for this information with a data sampling rate of once every 10 milliseconds.

• DTC U0140:87 (Lost Communication With Body Control Module: Missing Message) - set by the BCM-B  if data messages received from the SJB  over the MS-CAN are missing for 5 seconds or longer.
• DTC U0422:68 (Invalid Data Received From Body Control Module: Event Information) - a continuous memory and on-demand DTC that sets when the BCM-B  does not receive an ignition status message for longer than 3 seconds with an ignition switch position message having been received.

This pinpoint test is intended to diagnose the following: 

• Module communication
• BCM-B 
• SJB