Circuit Description

Modules connected to class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged between modules. In addition to this, state of health messages are transmitted by each module on class 2 serial data circuit about once every two seconds. When module detects no messages and a high voltage on class 2 serial data circuit for approximately 3 seconds, code U1301 is set and setting of all other class 2 serial communication DTCs is inhibited.

When DTC U1301 sets, module inhibits setting of all other class 2 serial data DTCs. Module uses default values for all parameters received on class 2 serial data circuit.

A current U1301 will clear when a valid class 2 serial data message is detected on class 2 serial data circuit or at end of current ignition cycle. A history U1301 can be cleared with scan tool.