Testing the Serial Data Circuits for an Open/High Resistance

2013 Buick Regal Turbo Premium, Standard TransSECTION Testing the Serial Data Circuits for an Open/High Resistance
WARNING: This page is about a different car, the 2011 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
    NOTE: A control module that has only one pair of high speed GMLAN serial data circuits and no internal terminating resistor should not be disconnected during this diagnostic test. A control module with a single pair of serial data circuits and no internal terminating resistor that has an open/high resistance would be diagnosed in the single control module not communicating diagnostic.
    The serial data circuits directly between a control module and the DLC do not need to be tested.
  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 and has 2 or more pairs of serial data circuits or an internal terminating resistor.
  2. Ignition OFF and all vehicle systems OFF, key out of the ignition switch, all access doors closed. It may take up to 2 minutes for all vehicle systems to power down. Test for greater than 140 Ξ© 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 greater than 140 Ξ©.
    • If each pair of serial data circuits is less 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 which has 2 or more pairs of serial data circuits or an internal terminating resistor, in the direction of the open circuit.
  5. Ignition OFF and all vehicle systems OFF, key out of the ignition switch, all access doors closed. It may take up to 2 minutes for all vehicle systems to power down. Test for greater than 140 Ξ© 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 greater than 140 Ξ©.
    • If each pair of serial data circuits is less than the specified range, replace the control module that was just disconnected.
  6. Repeat step 3 until one of the following conditions are isolated:
    • An open/high resistance on the serial data circuit between 2 control modules or splice packs, if equipped
    • An open/high resistance on the serial data circuit between a control module and a terminating resistor
    • An open/high resistance terminating resistor
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