Headlamp Aiming Procedure

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Headlamp Aiming Procedure
WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
  1. Park the vehicle square with the screen, with the headlamps directly over this reference line.
  2. Ensure that the components are in place if other work has been done on the vehicle.
  3. Ensure that the vehicle is on a level surface.
  4. Stop all other work on the vehicle.
  5. Ensure that the vehicle has half a tank, or less, of fuel.
  6. Close all of the doors.
  7. Rock the vehicle from side to side in order to stabilize the suspension and level the vehicle.
  8. Line up the centerline of the vehicle with the centerline of the aiming screen.
    • Mark the vertical center of the rear and front windows using tape.
    • Use these lines as sights in order to line up the centerline of the vehicle and the screen.
  9. Adjust the vertical tapes on the screen in order to match the vertical centerline of each low beam headlamp.

    Measure the distance from the centerline of the low beam lamp.

  10. Adjust the horizontal tapes on the screen in order to match the horizontal centerline of each low beam headlamp.

    Measure the height from the floor to the center of the low beam.

  11. Turn on the low beam headlamps.
  12. Observe the left and the top edges of the high intensity zone on the screen.
  13. Adjust the headlamps to the following specifications:
    • The top edge of the center of intensity on the screen for the low beam should be less than 101.6 mm (4 in) above or below the cross section of the headlamp centerlines.
    • The left edge of the center of intensity on the screen for the low beam should be less than 101.6 mm (4 in) to the left or right of the cross section of the headlamp centerlines.
  14. Use a Phillips screwdriver (1) in order to aim the headlamps. The adjusting gear (2) on the headlamp adjusts the headlamp vertically. There is no horizontal adjustment to the headlamp.
    Fig 1: Aiming Headlamp Using Screwdriver
    G01433469Courtesy of GENERAL MOTORS CORP.
RENDER: 1.0x

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When to See a Mechanic

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

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