DTC U1301: Class II Data Link High - L81: Notes

Fig 1: Class II Data Link High Schematic

Courtesy of GENERAL MOTORS CORP.

The Class II serial data link is configured in a ring used to communicate information between control modules. The controllers on the Class II link use a variable pulse width modulated square wave of 0 to 7 volts for communication. Zero volts equals a low state or logic "0" and 7 volts equals a high state or logic "1". The Body Control Module (BCM), Powertrain Control Module (PCM) - L61 only, Sensing and Diagnostic Module (SDM), auto climate control module (if equipped) or OnStar CIM (if equipped), monitor the Class II link for low and high voltage faults.