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Circuit/System Testing

WARNING: This page is about a different car, the 2018 GMC Canyon and 2018 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.
    NOTE:

    Each component with backlighting may need to be disconnected to isolate a short to voltage or short to ground. Use the schematics to identify the following:

    • Backlighting components the vehicle is equipped with
    • Each component's control and ground circuit terminals
    • Component locations on the backlighting control circuit
  1. Ignition OFF, disconnect the harness connectors at the components listed below.
    • S48A Multifunction Switch - Instrument Panel
    • S77 Transfer Case Shift Control Switch
    • S79D Window Switch - Driver
  2. Ignition ON, place the dimmer switch in the HIGH position for high backlighting intensity.
    3. NOTE:

    The test lamp in the following step will illuminate at LOW intensity. This is normal circuit operation and does not indicate a circuit malfunction.

  3. Verify a test lamp illuminates between each control circuit terminal listed below and ground.
    • S48A Multifunction Switch - Instrument Panel terminal 2
    • S77 Transfer Case Shift Control Switch terminal 4
    • S79D Window Switch - Driver terminal 11
    • If the test lamp does not illuminate 
    1. Ignition OFF, disconnect the X1 harness connector at the K9 Body Control Module.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module.
    • Go to next step: If the test lamp illuminates 
  4. Place the dimmer switch in the LOW position for low backlighting intensity.
  5. Verify a test lamp does not illuminate at FULL intensity between each control circuit terminal listed below and ground.
    • S48A Multifunction Switch - Instrument Panel terminal 2
    • S77 Transfer Case Shift Control Switch terminal 4
    • S79D Window Switch - Driver terminal 11
    • If the test lamp illuminates at full intensity 
    1. Ignition OFF, disconnect the X1 harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the control circuit terminal and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module.
    • Go to next step: If the test lamp does not illuminate at full intensity 
  6. Test or replace the inoperative component.
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