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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 87 (Lighting System - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> Dome Lamps Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

Dome Lamps Malfunction - Test 1`

  1. Ignition off, disconnect the X1 connector at the A98 Front Overhead Console Assembly, ignition ON.
  2. Verify a test lamp illuminates between terminal 12 and terminal 1.
    • If the test lamp does not illuminate 
    1. Test circuit 2350 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit or ground connection.
      • Go to next step: If an open/high resistance is not found.
    2. Test circuit 4540 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found.
    3. Test circuit 4540 for a short to ground.
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found
    4. Replace the X51A Fuseblock - Instrument Panel.
    • Go to next step: If the test lamp does illuminate 
  3. Ignition Off, connect the X1 connector at the A98 Front Overhead Console Assembly.
  4. Disconnect the connector at the appropriate component below, ignition ON:
    • E37SL Dome/Reading Lamps - 2nd Row Left
    • E37SR Dome/Reading Lamps - 2nd Row Right
    • A3L Sunshade - Left
    • A3R Sunshade - Right
  5. Connect a test lamp between terminal 1 and the appropriate ground circuit terminal below:
    • E37SL Dome/Reading Lamps - 2nd Row Left - terminal 3
    • E37SR Dome/Reading Lamps - 2nd Row Right - terminal 3
    • A3L Sunshade - Left - terminal 2
    • A3R Sunshade - Right - terminal 2
  6. Verify the test lamp turns ON and OFF while commanding the Dome/Reading Lamps Front Overhead Console ON and OFF with the scan tool.
    • If the test lamp does not illuminate 
    1. Test circuit 2350 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit or ground connection.
      • Go to next step: If an open/high resistance is not found
    2. Test the appropriate circuit below for an open/high resistance:
      • E37SL Dome/Reading Lamps - 2nd Row Left - 2903
      • E37SR Dome/Reading Lamps - 2nd Row Right - 2905
      • A3L Sunshade - Left - 4785
      • A3R Sunshade - Right - 2369
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found
    3. Test appropriate circuit below for a short to ground:
      • E37SL Dome/Reading Lamps - 2nd Row Left - 2903
      • E37SR Dome/Reading Lamps - 2nd Row Right - 2905
      • A3L Sunshade - Left - 4785
      • A3R Sunshade - Right - 2369
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found
    4. Replace the A98 Front Overhead Console Assembly
    • If the test lamp is always illuminated 
    1. Test the appropriate circuit for a short to voltage:
      • E37SL Dome/Reading Lamps - 2nd Row Left - 2903
      • E37SR Dome/Reading Lamps - 2nd Row Right - 2905
      • A3L Sunshade - Left - 4785
      • A3R Sunshade - Right - 2369
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found.
    2. Replace the A98 Front Overhead Console Assembly.
    • If the test lamp turns ON and OFF 
  7. Replace the appropriate component below.
    • E37SL Dome/Reading Lamps - 2nd Row Left
    • E37SR Dome/Reading Lamps - 2nd Row Right
    • A3L Sunshade - Left
    • A3R Sunshade - Right

Dome Lamps Malfunction - Test 2

  1. Ignition Off, disconnect the connector at the appropriate component below, ignition ON:
    • E37SL Dome/Reading Lamps - 2nd Row Left
    • E37SR Dome/Reading Lamps - 2nd Row Right
    • A3L Sunshade - Left
    • A3R Sunshade - Right
  2. Verify a test lamp illuminates between the appropriate terminal below and B+.
    • E37SL Dome/Reading Lamps - 2nd Row Left - terminal 3
    • E37SR Dome/Reading Lamps - 2nd Row Right - terminal 3
    • A3L Sunshade - Left - terminal 2
    • A3R Sunshade - Right - terminal 2
    • If the test lamp does not illuminate 

      Repair the open/high resistance on ground circuit 2350 or the ground connection.

    • Go to next step: If the test lamp illuminate 
  3. Verify a test lamp illuminates between the appropriate terminal below and ground.
    • E37SL Dome/Reading Lamps - 2nd Row Left - terminal 4
    • E37SR Dome/Reading Lamps - 2nd Row Right - terminal 4
    • A3L Sunshade - Left - terminal 1
    • A3R Sunshade - Right - terminal 1
    • If the test lamp does not illuminate 
    1. Test the appropriate circuit for an open/high resistance:
      • E37SL Dome/Reading Lamps - 2nd Row Left - 2904
      • E37SR Dome/Reading Lamps - 2nd Row Right - 2906
      • A3L Sunshade - Left - 4785
      • A3R Sunshade - Right - 2369
      • If an open/high resistance is found, repair the fault on the circuit or ground connection.
      • Go to next step: If an open/high resistance is not found
    2. Test the appropriate circuit below for a short to ground:
      • E37SL Dome/Reading Lamps - 2nd Row Left - 2904
      • E37SR Dome/Reading Lamps - 2nd Row Right - 2906
      • A3L Sunshade - Left - 4785
      • A3R Sunshade - Right - 2369
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found
    3. Replace the A98 Front Overhead Console Assembly
    • Go to next step: If the test lamp illuminates 
  4. Test the appropriate circuit for a short to voltage:
    • E37SL Dome/Reading Lamps - 2nd Row Left - 2904
    • E37SR Dome/Reading Lamps - 2nd Row Right - 2906
    • A3L Sunshade - Left - 4785
    • A3R Sunshade - Right - 2369
    • If a short to voltage is found, repair the fault on the circuit.
    • Go to next step: If a short to voltage is not found
  5. Replace the appropriate component below.
    • E37SL Dome/Reading Lamps - 2nd Row Left
    • E37SR Dome/Reading Lamps - 2nd Row Right
    • A3L Sunshade - Left
    • A3R Sunshade - Right
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