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Circuit/System Testing

WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Courtesy Lamp Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate courtesy lamp.
  2. Test for less than 5 Ω between the ground circuit terminal and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal and the ground circuit terminal.
  4. Ignition ON, command the Courtesy Lamps ON and OFF with the scan tool. The test lamp should turn ON and OFF.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, replace the courtesy lamp.

Door Open Switch Malfunction - Front w/AN3

  1. Ignition OFF, disconnect the harness connector at the door latch assembly.
  2. Test for less than 10.0 Ω between the ground circuit terminal listed below and ground.
    • Driver door latch - terminal 8
    • Passenger door latch - terminal 3
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Door Ajar Switch parameter is INACTIVE.
    • If the scan tool displays ACTIVE, test the signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the door control module.
      • Driver door open switch - terminal 6
      • Passenger door open switch - terminal 1
  4. Install a 3 A fused jumper wire between the signal circuit terminal listed below and ground. Verify the scan tool Door Open Switch parameter is ACTIVE.
    • Driver door open switch - terminal 6
    • Passenger door open switch - terminal 1
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the door control module.
  5. If all circuits test normal, replace the door latch assembly.

Door Open Switch Malfunction - Front w/o AN3

  1. Ignition OFF, disconnect the harness connector at the door latch assembly.
  2. Test for less than 10.0 Ω between the ground circuit terminal listed below and ground.
    • Terminal 8 (with AU3)
    • Terminal 6 (without AU3)
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Door Ajar Switch parameter is INACTIVE.
    • If the scan tool displays ACTIVE, test the signal circuit terminal 9 for a short to ground. If the circuit tests normal, replace the BCM.
  4. Install a 3 A fused jumper wire between signal circuit terminal 9 and ground. Verify the scan tool Door Ajar Switch parameter is ACTIVE.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, replace the door latch assembly.

Door Open Switch Malfunction - Rear

  1. Ignition OFF, disconnect the harness connector at the rear door latch assembly.
  2. Interior lamps OFF, test for less than 10.0 Ω between the ground circuit terminal listed below and ground.
    • Left rear door latch assembly - terminal 6
    • Right rear door latch assembly - terminal 3
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify a test lamp illuminates between the door open switch signal circuit terminal listed below and ground.
    • Left rear door open switch - terminal 4
    • Right rear door open switch - terminal 1
    • If the test lamp does not illuminate, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  4. Install a 3 A fused jumper wire between the signal circuit terminal listed below and ground. Verify the courtesy lamps illuminate and remain illuminated.
    • Left rear door open switch - terminal 4
    • Right rear door open switch - terminal 1
    • If the courtesy lamps do not remain illuminated, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, replace the rear door latch assembly.

Dome/Interior Lamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
  2. Test for less than 5 Ω between the ground circuit terminal 8 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Ctsy. Lamp Actv. Reason parameter is Off.
    • If the scan tool parameter is Manual or Manual Defeat, test the signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the BCM.
      • Manual terminal 12
      • Manual Defeat terminal 9
  4. Install a 3 A fused jumper wire between the signal circuit terminal 12 and the ground circuit terminal 8. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Manual.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. Install a 3 A fused jumper wire between the signal circuit terminal 9 and the ground circuit terminal 8. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Manual Defeat.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

Reading Lamps Malfunction

  1. Ignition OFF, disconnect the X2 harness connector at the BCM.
  2. Verify a test lamp illuminates between the IS LPS fuse B+ circuit terminal 1 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  3. Reconnect the X2 harness connector at the BCM.
  4. Disconnect the harness connector at the appropriate courtesy/reading lamp assembly.
  5. Scan tool OFF, doors CLOSED, interior lamps OFF, test for less than 5.0 Ω between the ground circuit terminal B and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  6. Verify a test lamp illuminates between the control circuit terminal C and ground.
    • If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  7. Remove the IS LPS fuse and verify the test lamp turns OFF.
    • If the test lamp remains illuminated, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  8. If all circuits test normal, replace the courtesy/reading lamp assembly.

Vanity Mirror Lighting Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate vanity mirror lamp.
  2. Test for less than 5 Ω between the ground circuit terminal B and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the signal circuit terminal A and ground.
    • If the test lamp does not illuminate, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  4. Connect the harness connector at the vanity mirror lamp.
  5. Remove the IS LPS fuse and verify the test lamp turns OFF.
    • If the test lamp remains illuminated, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  6. If all circuits test normal, replace the vanity mirror lamp.

Outside Rearview Mirror Illumination Malfunction

  1. Disconnect the harness connector at the appropriate exterior illumination lamp.
  2. Ignition ON, verify that a test lamp illuminates between the exterior illumination lamp supply circuit terminal and ground.
    • If the test lamp does not illuminate, test the exterior illumination lamp supply circuit for a short to ground or an open/high resistance.
  3. Connect a test lamp between the low side control circuit terminal and the exterior illumination lamp supply circuit terminal.
  4. Command the Puddle/Courtesy Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the inoperative door switch.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the inoperative door switch.
  5. If all circuits test normal, test or replace the exterior illumination lamp.
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