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Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 271 (Lighting System - DTC B0655 To DTC B3890) >> Diagnostic Information and Procedures >> DTC B2575 or B2699: Headlamps Control Circuit >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.

DTC B2575

  1. Ignition OFF, disconnect the X1 harness connector at the K9 Body Control Module, ignition ON.
  2. Verify a test lamp illuminates between the B+ circuit terminal 3 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF, disconnect the X1 harness connector at the X53A Fuse Block - Rear Body.
    2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF, disconnect the X1 harness connector at the X53A Fuse Block - Rear Body.
    2. Test for infinite resistance between the B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the X53A Fuse Block - Rear Body.
    • If the test lamp illuminates 
  3. Ignition OFF, connect the X1 harness connector at the K9 Body Control Module.
  4. Ignition OFF, exterior lamps OFF, remove the E4G Headlamp - Left Low Beam. It may take up to 2 min for all vehicle systems to power down.
  5. Test for less than 15 Ω between the ground circuit terminal B and ground.
    • If 15 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 15 Ω 
  6. Connect a test lamp between the control circuit terminal A and ground, ignition ON.
  7. Verify the test lamp turns ON and OFF when commanding the Left Low Beam Headlamp ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the X4 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.
      • 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.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the X4 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.
    • If the test lamp turns ON and OFF 
  8. Test or replace the E4G Headlamp - Left Low Beam.

DTC B2699

  1. Ignition OFF, disconnect the X1 harness connector at the K9 Body Control Module, ignition ON.
  2. Verify a test lamp illuminates between the B+ circuit terminal 2 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF, disconnect the X3 harness connector at the X53A Fuse Block - Rear Body.
    2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF, disconnect the X3 harness connector at the X53A Fuse Block - Rear Body.
    2. Test for infinite resistance between the B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the X53A Fuse Block - Rear Body.
    • If the test lamp illuminates 
  3. Ignition OFF, connect the X1 harness connector at the K9 Body Control Module.
  4. Ignition OFF, exterior lamps OFF, remove the E4H Headlamp - Right Low Beam. It may take up to 2 min for all vehicle systems to power down.
  5. Test for less than 15 Ω between the ground circuit terminal B and ground.
    • If 15 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 15 Ω 
  6. Connect a test lamp between the control circuit terminal A and ground, ignition ON.
  7. Verify the test lamp turns ON and OFF when commanding the Right Low Beam Headlamp ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the X4 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.
      • 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.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the X4 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.
    • If the test lamp turns ON and OFF 
  8. Test or replace the E4H Headlamp - Right Low Beam.
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