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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 High Speed GMLAN Device >> Circuit/System Testing >> Testing the Serial Data Circuits for a Short between the Circuits

Testing the Serial Data Circuits for a Short between the Circuits

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.
  1. Ignition OFF, disconnect the harness connectors with the high speed GMLAN serial data circuits at an easily accessible control module that is not communicating.
  2. Ignition OFF for 60 seconds, test for less than 35 Ω between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are less than 35 Ω.
    • If each pair of serial data circuits is greater than the specified range, replace the control module that was disconnected.
  3. Connect the harness connectors at the control module that was disconnected.
  4. Disconnect the harness connectors with the high speed GMLAN serial data circuits at another control module, in the direction of the circuits shorted together.
  5. Ignition OFF for 60 seconds, test for less than 35 Ω between each pair of serial data circuits at the control module connector that was just disconnected. Verify that one pair of serial data circuits are less than 35 Ω.
    • If each pair of serial data circuits is within the specified range, replace the control module that was just disconnected.
  6. Repeat step 3 until one of the following conditions are isolated:
    • Serial data circuits shorted together between 2 control modules
    • Serial data circuits shorted together between a control module and a terminating resistor
    • A shorted terminating resistor
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