Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 921 (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 2003 GMC Sonoma, 2003 GMC Jimmy, 2003 Chevrolet S10 Pickup, and 2003 Chevrolet Blazer. However, it is still accessible from the selected car via links, so may be relevant.
- Park the vehicle square with the screen (1). Park the vehicle with the headlamps directly over the reference line (6).
- Ensure that all of the components are in place, if work has been completed on the vehicle.
- Ensure that the vehicle is on a level surface.
- Stop all of the other work on the vehicle.
- Ensure that the vehicle has 1/2 tank of fuel or less.
- Close the vehicle doors.
- Rock the vehicle sideways.
- Align the centerline of the vehicle with the centerline (4) of the aiming screen by completing the following steps:
- Mark the vertical center of the rear and front windows with tape.
- Use these lines as sight lines in order to match the centerline of the vehicle with the screen.
- Adjust the vertical tapes (2) on the screen in order to match the vertical centerline of each low beam lamp.
- Measure the distance from the centerline of the vehicle to the centerline of a low beam lamp.
- Adjust the horizontal tapes (3) on the screen in order to match the horizontal centerline of each low beam lamp.
- Measure the height (5) from the floor to the center of a low beam.
- Illuminate the low beam lamps.
- Observe the left and top edges of the high intensity zone on the screen.
- Adjust the headlamps in order to accomplish the following results:
- The top edge of each high intensity zone must be within 50.8 mm (2 in) above to 63.5 mm (2.5 in) below the horizontal centerlines.
- The left edge of each high intensity zone must be within 101.6 mm (4 in) to the left or to the right of the vertical centerlines.
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When to See a Mechanic
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.