Circuit/System Description

The serial data is transmitted over a single wire to the appropriate control modules. The transmission speed for GMLAN low speed is up to 83.33 Kb/s. Under normal vehicle operating conditions, the speed of the buss is 33.33 Kb/s. The control modules toggle the serial data circuit between 0-5 V during normal communications. To wake the control modules connected to the GMLAN low speed serial data circuit, a voltage wake up pulse of 10 V is sent out. If serial data is lost, control modules will set a no communication code against the non-communicating control module. A loss of serial data communications DTC does not represent a failure of the module that set it.