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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 338 (Lighting System - Diagnostic Information And Procedures (2 Of 2)) >> Diagnostic Information and Procedures >> Headlamp Leveling Malfunction (Automatic) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT5. However, it is still accessible from the selected car via links, so may be relevant.

Headlamp Assembly Malfunction

  1. Ignition/vehicle OFF, exterior lamps OFF, disconnect the X1 harness connector at the E13LA Headlamp Assembly - Left.
  2. Verify a test lamp illuminates between ground circuit terminal 14 and B+.
    • If the test lamp does not illuminate 
    1. Repair the open/high resistance on the ground circuit or ground connection.
    • Go to next step: If the test lamp illuminates 
  3. Ignition ON/vehicle in service mode, verify a test lamp illuminates between B+ circuit terminal 13 and ground.
    • If the test lamp does not illuminate and the fuse is OPEN 
    1. Test circuit 1240 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
    2. Replace the E13LA Headlamp Assembly - Left
    • If the test lamp does not illuminate and fuse F5UA is OK 
    1. Test circuit 1240 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
    2. Replace the X50A Fuse Block - Underhood
    • If the test lamp illuminates and fuse F5UA is OK 
  4. Replace the appropriate E13 Headlamp Assembly with the leveling fault.

Suspension Position Sensor Malfunction

  1. Ignition/vehicle off, disconnect the harness connector at the appropriate component:
    • B152F Front Suspension Automatic Forward Lighting Position Sensor
    • B152R Rear Suspension Automatic Forward Lighting Leveling Position Sensor
  2. Ignition on/vehicle in service mode, verify a test lamp illuminates between the low reference circuit terminal 2 and B+.
    • If the test lamp does not illuminate 
    1. Test the appropriate circuit for an open/high resistance:
      • B152F Front Suspension Automatic Forward Lighting Position Sensor = Circuit 7526
      • B152R Rear Suspension Automatic Forward Lighting Leveling Position Sensor = Circuit 2185
      • 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.
    2. Replace the E13LA Front Headlamp - Left.
    • Go to next step: If the test lamp illuminates 
  3. Test for 4.8 - 5.2 V between 5 V reference circuit terminal 1 and ground.
    • If less than 4.8 V 
    1. Test the appropriate circuit for a short to ground:
      • B152F Front Suspension Automatic Forward Lighting Position Sensor = Circuit 7524
      • B152R Rear Suspension Automatic Forward Lighting Position Sensor = Circuit 2165
      • 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.
    2. Test the appropriate circuit for an open/high resistance:
      • B152F Front Suspension Automatic Forward Lighting Position Sensor = Circuit 7524
      • B152R Rear Suspension Automatic Forward Lighting Position Sensor = Circuit 2165
      • 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. Replace the E13LA Front Headlamp - Left.
    • If greater than 5.2 V 
    1. Test the appropriate circuit for a short to voltage:
      • B152F Front Suspension Automatic Forward Lighting Position Sensor = Circuit 7524
      • B152R Rear Suspension Automatic Forward Lighting Position Sensor = Circuit 2165
      • 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 E13LA Front Headlamp - Left.
    • Go to next step: If between 4.8 - 5.2 V 
  4. Test for less than 1 V between the signal circuit terminal 3 and ground.
    • If 1 V or greater 
    1. Test the appropriate circuit for a short to voltage:
      • B152F Front Suspension Automatic Forward Lighting Position Sensor = Circuit 7525
      • B152R Rear Suspension Automatic Forward Lighting Position Sensor = Circuit 2184
      • 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 E13LA Front Headlamp - Left.
    • Go to next step: If less than 1 V 
  5. Ignition/vehicle OFF, disconnect the X2 harness connector at the E13LA Front Headlamp - Left.
  6. Test for infinite resistance between the signal circuit terminal 3 at the suspension sensor and ground.
    • If less than infinite resistance 
    1. Repair the short to ground on the appropriate circuit:
      • B152F Front Suspension Automatic Forward Lighting Position Sensor = Circuit 7525
      • B152R Rear Suspension Automatic Forward Lighting Position Sensor = Circuit 2184
    • Go to next step: If infinite resistance 
  7. Test the appropriate circuit for an open/high resistance:
    • B152F Front Suspension Automatic Forward Lighting Position Sensor = Circuit 7525
    • B152R Rear Suspension Automatic Forward Lighting Position Sensor = Circuit 2184
    • If an open/high resistance is found 

      Repair the open/high resistance in the circuit.

    • Go to next step: If an open/high resistance is not found 
  8. Replace the appropriate B152 Suspension Automatic Forward Lighting Position Sensor
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