Circuit Description

Modules connected to the class 2 serial data link monitor the link for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. In addition to this, Node Alive (State Of Health) messages are transmitted by each module on the class 2 serial data link about once every 2 seconds. When the modules detects no message and a low voltage on the class 2 serial data link for about 3 seconds, DTC U1300 is set and setting of all other class 2 serial communication DTCs is inhibited.

Conditions for setting DTC:

• Voltage supplied to module is in normal operating voltage range (about 9-16 volts).
• No valid class 2 messages detected on serial data link.
• Voltage level detected on class 2 serial data link is low.
• Conditions are all met simultaneously for 3 seconds.