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Home >> Chevrolet >> 2014 >> Camaro Z/28 >> Repair and Diagnosis >> Engine Performance >> System >> Data Communication System >> Diagnostic Information and Procedures >> Scan Tool Does Not Communicate with Low Speed GMLAN Device >> Circuit/System Verification
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Circuit/System Verification

NOTE:

Use the schematic to identify the following:

  • Devices the vehicle is equipped with
  • Device and splice pack locations on the low speed GMLAN serial data circuit
  • The low speed GMLAN serial data circuit terminals for each device or splice pack
  1. Attempt to communicate with all devices on the low speed GMLAN serial data circuit. Refer to Data Link References .
  2. Verify which devices are communicating on the low speed GMLAN serial data circuit.
    • If only one device is not communicating 

      Diagnose that device only. Refer to DTC U0100-U02FF .

    • If one or more devices are communicating but not all 

      Refer to Circuit/System Testing - Testing the Serial Data Circuit for an Open/High Resistance.

    • If none of the devices are communicating 
  3. Ignition OFF, all access doors closed, all vehicle systems OFF, all keys at least 3m (9.8ft) away from vehicle. Disconnect the scan tool from the X84 Data Link Connector. The following tests will be done at the X84 Data Link Connector. It may take up to 2 minutes for all vehicle systems to power down.
  4. Test for less than 10Ω between the ground circuit terminal 5 and ground.
    • If 10Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2Ω in the ground circuit end to end.
      • If 2Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2Ω, repair the open/high resistance in the ground connection.
    • If less than 10Ω 
  5. Ignition ON.
  6. Test for less than 4.5V between the serial data circuit terminal 1 and ground.
    • If 4.5V or greater 

      Refer to Circuit/System Testing - Testing the Serial Data Circuits for a Short to Voltage.

    • If less than 4.5V 
  7. Ignition OFF, all access doors closed, all vehicle systems OFF, all keys at least 3m (9.8ft) away from vehicle. It may take up to 2 minutes for all vehicle systems to power down.
  8. Test for greater than 100Ω between the serial data circuit terminal 1 and ground.
    • If 100Ω or less 

      Refer to Circuit/System Testing - Testing the Serial Data Circuits for a Short to Ground.

    • If greater than 100Ω 
  9. Disconnect the appropriate harness connector at the first splice pack closest in the circuit to the X84 Data Link Connector.
  10. Test for less than 2Ω between the X84 Data Link Connector's serial data circuit terminal 1 and the splice pack harness connector's serial data input terminal.
    • If 2Ω or greater 

      Repair the open/high resistance in the serial data circuit.

    • If less than 2Ω 
  11. Replace the splice pack.
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