How do you make adjustments to a 99 bonneville headlights. Repairs were done to the front end and the headlights don't shine on the road now.

The way those bulbs fit on the lens housing, it is very easy to have one end tipped up. Check how the bulb is inserted and clipped into the lens housing. If that is good, check the lens housing to make sure it didn't get cocked some way.

Find level ground with a wall. Drive up to the wall and mark where the centre of your headlights are on the wall with a piece of tape. Back up 20 feet and turn your headlights on high beam. Using the adjusting knobs make each light shine directly on the spot. Low beam adjusts itself down and to the left/right (away from oncoming traffic depending on what side of the road you drive on)

if you have a screwdriver with adjustable tips, just use the screwdriver without a tip. put it over the screw like it's a sockrt wrench and viola!!

You should not try to adjust the headlights yourself because if you get them to where they shine in other drivers eyes when going down the road you could be fined for it.If you don't know how or where the beams should shine you could make it worse,they have to be a certain hieght and a certain angle.

Open your hood and right above both your headlights, there should be a bolt, screw or nut. It should be the only bolt directly over the center of the headlight. You should be able to tell that it has something to do with the headlight. I believe if you turn it like your tightening it that will bring it down. If not then youll have to go other way but I'm pretty sure thats right. You may not be able to see much of a diff. when your standing in front of them so make sure you check them often while your doing it. Park in front of a wall when its kinda dark out or a garage. Park about 10 feet back from wall and adjust till there pointing where you want them. Good luck.

First check bulb is inserted and clipped in correctly most are awkward.did the inner part get disturbed etc.i dont know if ur model has auto adjust headlights but even if it does and the motors failed they can still be done manually.most have two nut shaped adjusters or take hex type key .i think u should check the stuff i started with.they dont just go out of adjustment without a cause

AIMING THE HEADLIGHTS

On 1989-91 vehicles, the headlights can be aimed using the adjusting screws located above and to the side of the headlight bulbs. A rough adjustment can be made while shining the headlights on a wall or on the rear of another vehicle, but headlight adjustment should really be made using proper headlight aiming equipment.
On 1992-98 vehicles, the aerodynamically styled headlights necessitate the use of headlight aiming kit 107-00003 or equivalent. The adjustable aimer adapters provided in the kit must be used to aim the headlights. Adjustment aimer adapter positions are moulded into the bottom edge of the headlight lens. Set and lock the adjustable adapters, attach each adapter to its mechanical aimer and aim the headlights according to the instructions in the kit.
Headlight aim adjustment should be made with the fuel tank approximately half full, the vehicle unloaded and the trunk empty, except for the spare tire and jacking equipment. Make sure all tires are inflated to the proper pressure.
The headlights must be properly aimed to provide the best, safest road illumination. The lights should be checked for proper aim and adjusted as necessary. Certain state and local authorities have requirements for headlight aiming; these should be checked before adjustment is made.

CAUTION About once a year, when the headlights are replaced or any time front end work is performed on your vehicle, the headlight should be accurately aimed by a reputable repair shop using the proper equipment. Headlights not properly aimed can make it virtually impossible to see and may blind other drivers on the road, possibly causing an accident. Note that the following procedure is a temporary fix, until you can take your vehicle to a repair shop for a proper adjustment.
Headlight adjustment may be temporarily made using a wall, as described below, or on the rear of another vehicle. When adjusted, the lights should not glare in oncoming car or truck windshields, nor should they illuminate the passenger compartment of vehicles driving in front of you. These adjustments are rough and should always be fine-tuned by a repair shop which is equipped with headlight aiming tools. Improper adjustments may be both dangerous and illegal.
For most of the vehicles covered by this guide, horizontal and vertical aiming of each sealed beam unit is provided by two adjusting screws which move the retaining ring and adjusting plate against the tension of a coil spring. There is no adjustment for focus; this is done during headlight manufacturing.
Because the composite headlight assembly is bolted into position, no adjustment should be necessary or possible. Some applications, however, may be bolted to an adjuster plate or may be retained by adjusting screws. If so, follow this procedure when adjusting the lights, BUT always have the adjustment checked by a reputable shop.
Before removing the headlight bulb or disturbing the headlamp in any way, note the current settings in order to ease headlight adjustment upon reassembly. If the high or low beam setting of the old lamp still works, this can be done using the wall of a garage or a building:

1. Park the vehicle on a level surface, with the fuel tank about 1 / 2 full and with the vehicle empty of all extra cargo (unless normally carried). The vehicle should be facing a wall which is no less than 6 feet (1.8m) high and 12 feet (3.7m) wide. The front of the vehicle should be about 25 feet from the wall.

See Figure 6



Fig. 6: Example of headlight adjustment screw location for composite headlamps

1. If aiming is to be performed outdoors, it is advisable to wait until dusk in order to properly see the headlight beams on the wall. If done in a garage, darken the area around the wall as much as possible by closing shades or hanging cloth over the windows.
2. Turn the headlights ON and mark the wall at the center of each light's low beam, then switch on the brights and mark the center of each light's high beam. A short length of masking tape which is visible from the front of the vehicle may be used. Although marking all four positions is advisable, marking one position from each light should be sufficient.

See Figures 7 and 8



Fig. 7: Low-beam headlight pattern alignment



Fig. 8: High-beam headlight pattern alignment

1. If neither beam on one side is working, and if another like-sized vehicle is available, park the second one in the exact spot where the vehicle was and mark the beams using the same-side light. Then switch the vehicles so the one to be aimed is back in the original spot. It must be parked no closer to or farther away from the wall than the second vehicle.
2. Perform any necessary repairs, but make sure the vehicle is not moved, or is returned to the exact spot from which the lights were marked. Turn the headlights ON and adjust the beams to match the marks on the wall.
3. Have the headlight adjustment checked as soon as possible by a reputable repair shop.

Hope thats helped (remember rated this) Good luck.

AIMING THE HEADLIGHTS

The headlights must be properly aimed to provide the best, safest road illumination. The lights should be checked for proper aim and adjusted as necessary. Certain state and local authorities have requirements for headlight aiming; these should be checked before adjustment is made.

CAUTION About once a year, when the headlights are replaced or any time front end work is performed on your vehicle, the headlight should be accurately aimed by a reputable repair shop using the proper equipment. Headlights not properly aimed can make it virtually impossible to see and may blind other drivers on the road, possibly causing an accident. Note that the following procedure is a temporary fix, until you can take your vehicle to a repair shop for a proper adjustment.
Headlight adjustment may be temporarily made using a wall, as described below, or on the rear of another vehicle. When adjusted, the lights should not glare in oncoming car or truck windshields, nor should they illuminate the passenger compartment of vehicles driving in front of you. These adjustments are rough and should always be fine-tuned by a repair shop which is equipped with headlight aiming tools. Improper adjustments may be both dangerous and illegal.
For most of the vehicles covered by this guide, horizontal and vertical aiming of each sealed beam unit is provided by two adjusting screws which move the retaining ring and adjusting plate against the tension of a coil spring. There is no adjustment for focus; this is done during headlight manufacturing.
Because the composite headlight assembly is bolted into position, no adjustment should be necessary or possible. Some applications, however, may be bolted to an adjuster plate or may be retained by adjusting screws. If so, follow this procedure when adjusting the lights, BUT always have the adjustment checked by a reputable shop.
Before removing the headlight bulb or disturbing the headlamp in any way, note the current settings in order to ease headlight adjustment upon reassembly. If the high or low beam setting of the old lamp still works, this can be done using the wall of a garage or a building:

1. Park the vehicle on a level surface, with the fuel tank about 1 / 2 full and with the vehicle empty of all extra cargo (unless normally carried). The vehicle should be facing a wall which is no less than 6 feet (1.8m) high and 12 feet (3.7m) wide. The front of the vehicle should be about 25 feet from the wall.

Fig. : Location of the aiming screws on most vehicles with sealed beam headlights




Fig. : Dual headlight adjustment screw locations-one side shown here (other side should be mirror image)



Fig. : Example of headlight adjustment screw location for composite headlamps

1. If aiming is to be performed outdoors, it is advisable to wait until dusk in order to properly see the headlight beams on the wall. If done in a garage, darken the area around the wall as much as possible by closing shades or hanging cloth over the windows.
2. Turn the headlights ON and mark the wall at the center of each light's low beam, then switch on the brights and mark the center of each light's high beam. A short length of masking tape which is visible from the front of the vehicle may be used. Although marking all four positions is advisable, marking one position from each light should be sufficient.

Fig. : Low-beam headlight pattern alignment



Fig. : High-beam headlight pattern alignment

1. If neither beam on one side is working, and if another like-sized vehicle is available, park the second one in the exact spot where the vehicle was and mark the beams using the same-side light. Then switch the vehicles so the one to be aimed is back in the original spot. It must be parked no closer to or farther away from the wall than the second vehicle.
2. Perform any necessary repairs, but make sure the vehicle is not moved, or is returned to the exact spot from which the lights were marked. Turn the headlights ON and adjust the beams to match the marks on the wall.
3. Have the headlight adjustment checked as soon as possible by a reputable repair shop.

Hope helped with this information. Good luck (remember rated this help).

AIMING THE HEADLIGHTS
The headlights must be properly aimed to provide the best, safest road illumination. The lights should be checked for proper aim and adjusted as necessary. Certain state and local authorities have requirements for headlight aiming; these should be checked before adjustment is made.

CAUTION About once a year, when the headlights are replaced or any time front end work is performed on your vehicle, the headlight should be accurately aimed by a reputable repair shop using the proper equipment. Headlights not properly aimed can make it virtually impossible to see and may blind other drivers on the road, possibly causing an accident. Note that the following procedure is a temporary fix, until you can take your vehicle to a repair shop for a proper adjustment.
Headlight adjustment may be temporarily made using a wall, as described below, or on the rear of another vehicle. When adjusted, the lights should not glare in oncoming car or truck windshields, nor should they illuminate the passenger compartment of vehicles driving in front of you. These adjustments are rough and should always be fine-tuned by a repair shop which is equipped with headlight aiming tools. Improper adjustments may be both dangerous and illegal.

For most of the vehicles covered by this guide, horizontal and vertical aiming of each sealed beam unit is provided by two adjusting screws which move the retaining ring and adjusting plate against the tension of a coil spring. There is no adjustment for focus; this is done during headlight manufacturing.


Because the composite headlight assembly is bolted into position, no adjustment should be necessary or possible. Some applications, however, may be bolted to an adjuster plate or may be retained by adjusting screws. If so, follow this procedure when adjusting the lights, BUT always have the adjustment checked by a reputable shop.
Before removing the headlight bulb or disturbing the headlamp in any way, note the current settings in order to ease headlight adjustment upon reassembly. If the high or low beam setting of the old lamp still works, this can be done using the wall of a garage or a building:

Park the vehicle on a level surface, with the fuel tank about 1 / 2 full and with the vehicle empty of all extra cargo (unless normally carried). The vehicle should be facing a wall which is no less than 6 feet (1.8m) high and 12 feet (3.7m) wide. The front of the vehicle should be about 25 feet from the wall.

Fig. Example of headlight adjustment screw location for composite headlamps

If aiming is to be performed outdoors, it is advisable to wait until dusk in order to properly see the headlight beams on the wall. If done in a garage, darken the area around the wall as much as possible by closing shades or hanging cloth over the windows. Turn the headlights ON and mark the wall at the center of each light's low beam, then switch on the brights and mark the center of each light's high beam. A short length of masking tape which is visible from the front of the vehicle may be used. Although marking all four positions is advisable, marking one position from each light should be sufficient.

Fig. Low-beam headlight pattern alignment




Fig. High-beam headlight pattern alignment

If neither beam on one side is working, and if another like-sized vehicle is available, park the second one in the exact spot where the vehicle was and mark the beams using the same-side light. Then switch the vehicles so the one to be aimed is back in the original spot. It must be parked no closer to or farther away from the wall than the second vehicle. Perform any necessary repairs, but make sure the vehicle is not moved, or is returned to the exact spot from which the lights were marked. Turn the headlights ON and adjust the beams to match the marks on the wall. Have the headlight adjustment checked as soon as possible by a reputable repair shop.
Hope helped with this (remember rated this help) Good luck.

The heater problem could be a vacuum issue. My 89 has vacuum operated acutators, so if you had all of that out, all the vacuum connections for the heater box and controls may not be connected correctly. I would check those first. The actual door is a flapper door inside the heater box up under the dash, probably center or slightly right of center. Follow all the ducts and where all of those go into the heater box is where the door is inside.

For the headlights, I like to adjust mine on a flat dark road. It is difficult to adjust them againist the side of a wall. If your truck suffered front end damage, there is a chance your core support is bent backwards which would affect the adjustment range of your headlights.
There are actual headlight aiming machines, and you could pay to have yours done, but I have had really good luck as well as getting them even when its dark and you can see whats going on and what kind of pattern the lights are shining.