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Home >> Chevrolet >> 2011 >> Chevy Express G2500, Van Cargo Extended, 6.6 L >> Repair and Diagnosis >> External Pages >> Different car >> Section 14 (Data Communication System) >> Diagnostic Information & Procedures >> Scan Tool Does Not Communicate With Low Speed GMLAN Device >> Circuit/System Description

Circuit/System Description

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2010 GMC Savana Special, 2010 GMC Savana Camper Special, 2010 GMC Savana, 2010 Chevrolet RV Cutaway, and 2010 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

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. Note: a loss of serial data communications DTC does not represent a failure of the module that set it.

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