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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 371 (LIGHTING SYSTEMS)REPAIR INSTRUCTIONSHEADLAMP AIMINGHEADLAMP AIMING PROCEDURE
1999 GMC Forward Control 5.7 R, Automatic

Headlamp Aiming Procedure

1999 GMC Forward Control 5.7 R, AutomaticSECTION Headlamp Aiming Procedure
WARNING: This page is about a different car, the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
  1. Open the hood.
  2. Measure from the floor to the center of the headlamp bulb. (Some headlamps have an aim dot marked on the headlamp lens).
  3. At the screen, measure from the floor and place the horizontal tape at the measured distance.
  4. Measure from the reference line on the floor to the left headlamp bulb centerline.
  5. At the screen, measure from the reference line and place the vertical tape at the measured distance.
  6. Measure from the reference line on the floor to the right headlamp bulb centerline.
  7. At the screen, measure from the reference line and place the vertical tape at the measured distance.
    Fig 1: Measuring From Floor To Center Of Headlamp Bulb
    G01736209Courtesy of GENERAL MOTORS CORP.

    Important:  Do not cover the headlamp, this may cause excessive heat build up.

  8. Turn on the low beam headlamps and block the light from projecting onto the screen from the passenger side headlamp.
  9. Adjust the vertical aim of the headlamps to the specifications required by the state and the local authorities, or as shown in step  8.
  10. Rotate the headlamp adjuster (1) to change the vertical aim of the headlamp.
  11. Repeat the aiming procedure for the passenger side headlamp while blocking the light from projecting onto the screen from the driver side headlamp.
  12. Close the hood.
  13. This illustration represents the visual optics left (VOL) pattern.
  14. This illustration represents the visual optics right (VOL) pattern.
  15. This illustration represents all headlamps, except the VOL and VOR.
  16. This illustration represents the high beam pattern for all headlamps, including VOL and VOR.
    Fig 2: Headlamp Pattern
    G01736210Courtesy 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.