When the headlight is installed in the vehicle’s light system, the headlight’s position is measured from the top of the vehicle, the hood, down to the center of the taillights. It’s then measured from the next most important place, in the middle of the taillights – which is usually in the center on a modern vehicle.
When the headlight is removed, the location marked on the light’s body indicates where to measure the next spot inside the hood, inside the taillights or on the inside of the hood.
You need both measurements to determine the distance that a taillight’s headlamp should be from the next spot. If the lights are mounted to separate mirrors, you have to measure from their outer edge just as you did when the lights were installed.
Why measure at the intersection of two taillights?
Tracking headlamps is much more reliable for determining their position than measuring their positions at intersections. It’s important to know that because the headlamps are tracking, you can get much more accurate results than by measuring at intersections.
In general, if you try to measure at intersections, you’ll see differences compared to headlight position.
How do you figure out where to remove the headlight?
This is a pretty simple question and often it will be, “Did the car just turn left with the on-ramp?” In some situations, you’ll find that it’s not the on-ramp that is causing the problem. It could be an over-slung vehicle, a parked car or even a parked vehicle where you can see the taillist from several places around the vehicle. That’s normal and should be addressed by your dealer.
In these situations, it’s not always easy to know precisely what’s causing the taillight problem, so you may have to remove and re-install the headlights to find the causes. We don’t have a technique for this, but some people try to find clues by looking at and using their headlights for awhile, and then take a look at the light-box at first light at an intersection.
Are there other possible causes other than the on-ramp for headlight problems?
We have an article on headlight problems. If you have any questions or tips about headlight removal, you can see the article here.
Other Headlight Tips:
Do your turn signals have to be mounted in the same