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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 652 (LIGHTING SYSTEMS)REPAIR INSTRUCTIONSHEADLAMP AIMINGHEADLAMP AIMING PROCEDURE
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Headlamp Aiming Procedure

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Headlamp Aiming Procedure
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
  1. Adjust the headlamps to the specifications required by state and local authorities.
  2. Align the left tires of the vehicle with the reference line extending from the screen with the headlamps aligned with the reference line.
  3. Remove any snow, ice or mud from the vehicle.
  4. The vehicle should be fully assembled and all other work stopped while the headlamp aiming is being done.
  5. The vehicle should be loaded to represent normal vehicle use.
  6. Tires should be properly inflated.
  7. Rock the vehicle to stabilize the suspension.
  8. Measure from the reference line on the floor to the left headlamp bulb centerline.
  9. At the screen, measure from the reference line and place the vertical tape at the measured distance.
    Fig 1: Aiming Headlamps
    G01802973Courtesy of GENERAL MOTORS CORP.
  10. Measure from the reference line on the floor to the right headlamp bulb centerline.
  11. At the screen, measure from the reference line and place the second vertical tape at the measured distance.
  12. Adjust the left and right headlamp horizontal aim to the vertical lines on the screen by turning the horizontal aiming screws.
  13. Measure from the floor to the aim dot marked on the left headlamp lens and subtract 51 mm (2 in).
  14. At the screen, measure from the floor and place the horizontal line at the previously calculated distance.
  15. Adjust the left headlamp to the horizontal line on the screen by turning the vertical aiming screw.
  16. Measure from the reference line on the floor to the aim dot marked on the right headlamp lens.
  17. At the screen, measure from the floor and place the horizontal line at the measured distance.
  18. Adjust the right headlamp to the horizontal line on the screen by turning the vertical aiming screw.
    Fig 2: Measuring Headlamp Horizontal Accuracy
    G01802974Courtesy of GENERAL MOTORS CORP.
RENDER: 1.0x

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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.