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HOMESERVICE MANUALSCHEVROLET2009AVALANCHE 6.0 Y, RWDREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMDATA COMMUNICATION SYSTEMDIAGNOSTIC INFORMATION AND PROCEDURESDTC U0100 - U0299CIRCUIT/SYSTEM TESTING
2009 Chevrolet Avalanche 6.0 Y, RWD

Circuit/System Testing

2009 Chevrolet Avalanche 6.0 Y, RWDSECTION Circuit/System Testing
NOTE: Use the schematic to identify the following:
  • Control modules the vehicle is equipped with
  • Control module locations on the low and high speed GMLAN serial data circuits
  • The control modules B+, ignition, ground, communication enable and serial data circuit terminals
  1. Determine the module that is not communicating. Refer to Control Module U Code List .
  2. Ignition OFF, disconnect the necessary harness connector of the module that is not communicating.
  3. Test for less than 10 Ω between each ground circuit terminal and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  4. If equipped, verify that a test lamp illuminates between each B+ circuit terminal and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test the control circuits of the control module for a short to ground. If the circuits test normal, replace the control module.
  5. If equipped, ignition ON, verify that a test lamp illuminates between each ignition circuit terminal and ground.
    • If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test the control circuits of the control module for a short to ground. If the circuits test normal, replace the control module.
    6. NOTE: Only the high speed GMLAN modules have a serial data communication enable circuit OR an accessory wakeup serial data circuit, and the BCM is the output for these circuits. Refer to the module schematics to identify which modules have these circuits.
  6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup circuit terminal and ground.
    • If the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
  7. Ignition OFF for 60 seconds, test for less than 5 Ω between the serial data circuit terminals and the DLC terminal listed below:
    • Class 2 serial data circuit terminal 2
    • Low speed GMLAN serial data terminal 1
    • High speed GMLAN serial data terminal 6 or 14
    • If greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module and a module setting the DTC or a serial data splice pack.
  8. If all circuits test normal, replace the control module that is not communicating.
RENDER: 1.0x

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