If your vehicle has a Xenon lighting fixture with auto beam adjustment, the headlight beams will respond accordingly to changes in the car’s load and to other factors, such as speed changes. During acceleration and when braking, the automatic headlight beam adjustment feature will auto-correct any changes in headlight function, so that a constant is maintained. In order for the auto-adjustment feature to work, however, a driver must first activate the ignition, and the car’s low beams must be turned on [most standard HID upgrades are low beam conversions].
Automatic headlight beam adjustments will only work effectively if the HID components themselves have been installed according to guidelines. Generally, HID headlight beams should face several inches lower than conventional halogen headlight beams, as the bright light produced by HIDs even on low beam settings can distract, or worse yet, blind a driver, particularly at night. If you test the aiming of the HID beams before finishing your headlight installation process, you can tell whether the lights are targeting the right area. To test, park your car in a garage about six feet from the wall. Turn on the stock halogen beams, and mark where the lights hit. After installing the new Xenon HID components, test the beams from the same distance. Adjust until they hit about 1.5-2 inches lower than the stock beams, unless there’s some other adjustment that’s already been made to reduce the effects of leveled HID lighting.
Once everything’s in proper working order from the get-go, the automatic headlight beam adjustment feature should be able to respond correctly to changes in a vehicle’s condition (total load, acceleration/braking speed, etc.).